SHEET METAL OPERATIONS

• BLANKING OPERATION: PIECE PART (BLANK or COMPONENT)

• PIERCING OPERATION: - HOLE OF ANY PROFILE

• NOTCHING OPERATION: SIDE CUTTING OF ANY PROFILE

• SHAVING OPERATION: MAKING UNIFORM, SMOOTH AND PRECISE OUTER CONTOUR

• TRIMMING OPERATION: MAKING UNIFORM AND SMOOTH OUTER

CONTOUR

• SIDE CAM PIERCING: SPECIAL HOLE MAIKKNG OPERATION IN DRAWN

CUPS

• DINKING OPERATION: FOR FIBRE MATERIAL

• LOVERING OPERATION: PASSAGE FOR AIR TO ENTER

• LANCING OPERATION: PARTIAL TEARING OPERATION

• BENDING OPERATION: FOR SHAPING OF PRE-CUT BLANKS OR SHEETS IN STRAIGHT AXIS

• FORMING OPERATION: FOR SHAPING IN CURVED AXIS

• CURLING OPERATION: FOR HINGING, PIN GUIDEING PURPOSE

• FLANGING OR EXTRUDING: FOR ORIGINATING THREADS IN SHEET

METAL

• DRAW OPERATION: TO SHAPE FLAT BLANK SHEET METAL INTO CUP

• COINING OPERATION: SOLID BLANK IS SQUEEZED TO REQUIRED PROFILE

• STAMPING OPERATION: DEPRESSED LETTERS, SYMBOLS, LOGOS ARE

POSSIBLE ON SHEET METALS

• EMBOSSING OPERATION: REQUIRED FOR PLACING SCREWS, FOR RIVETTING ETC ON SHEET METALS

• BULGING: SWELLENING OF THE IRREGULAR PROFILE ON THE TUBE SURFACE

INTRODUCTION TO PRESS TOOLS

Sheet metal components are produced by a device called “Press tool”. Generally, these tools are Cold working and manufactured to improve the productivity of the components qualitatively and quantitatively. APPLICATION OF PRESS TOOLS

Press tools are extensively used for the production of sheet metal components in mass.

Examples

Most of the products namely, Television, Tape recorder, Radio, Refrigerator, Automobile Car, Scooter, Motorbike, Watch, Computer etc, consist number of components made of either plastic or sheet metal. DEFINITION FOR PRESS TOOLS

Press tool as a device used for producing sheet components in large volume by applying an external force with the help of a machine tool called “PRESS”.

Press tools are mainly manufactured for high rate of sheet component production. If the requirement of components is less (less than 1000 numbers), these devices are not economical.

Hence, press tools are categorized according to the requirement,

CATEGORIES OF PRESS TOOLS � Simple press tool � Medium production press tool � Large scale production press tool � High speed press tool � Precision press tool � Horological press tool (watch component)

SPECIAL PURPOSE PRESS TOOLS

• Cantilever press tool

• Side cam press tool

• Straight cam press tool

• Angular cam press tool

• Curvature cam press tool TYPES OF PRESS OPERATION

• Cutting press tool

• Non - cutting press tool

• Hybrid press tool (Cutting and Non-Cutting operation)

TYPICAL SKETCH OF A PRESS TOOL WITH BASIC PARTS

Space for Notes:

ACTIVITIES OF SHEET METAL INDUSTRIES Sheet metal industries have a significant role in the present industrial society.

The production of sheet metal components have increased in many folds due to continuous research and development.

In our country, major activities lies with sheet metal industries only. As per the

present survey, it occupies 55% of the industrial supplies.

Sheet metal industries are classified into many categories.

1. Fabrication industries • House hold products

• Conventional products

• Commercial products

• Non – precision industrial products • General engineering products

2. Medium precision industries

• Engineering products of second priority

3. High precision industries • Aero space products

• High end engineering products

• Products with special material

• Products for research and development

For any industry to run efficiently 3 M are very important. 1) M = Money 2) M = Machine 3) M = Men

Money and Machine are supported by many agencies and consultancies,

whereas, it is difficult to find skilled man power with good knowledge of both theoretical and practical.

SIGNIFICANT POINTS

• Most Tool and die makers need 4 or 5 years of classroom instruction and on-the-job training to become fully qualified.

• Employment is projected to decline because of strong foreign competition and advancements in automation.

• Despite the decline in employment, excellent job opportunities are expected.

NATURE OF THE TOOL MAKERS

1. Tool and die makers are among the most highly skilled workers in manufacturing.

2. These workers produce and repair tools, dies, and special guiding and

holding devices that enable machines to manufacture a variety of products we use daily — from clothing and furniture to heavy equipment and parts for aircraft.

3. Toolmakers produce precision tools. 4. They are capable of handling machines that are used to cut, shape, and

form metal and other materials. 5. They also produce jigs and fixtures that hold workpiece while it is bored,

stamped or drilled and handle gauges and other measuring devices.

6. Die makers construct metal forms called “DIES”, that are used to cut metal in stamping.

7. Tool & Die makers use computer-aided design (CAD) to develop products

and parts. 8. Tool & Die makers set up a test run using the tools or dies they have

made to make sure that the manufactured parts meet specifications.

9. If problems occur, they compensate by adjusting the tools or dies.

10. They study metalworking processes, such as heat treating and plating.

11. Classroom training usually consists of tool designing, tool processing, blue print reading.

TRAINING, QUALIFICATIONS AND ADVANCEMENT

1. Even after completing a formal training program, Tool & Die makers still need years of experience to become highly skilled.

2. Most specialize in making certain types of Press tools, Moulds, or Dies.

3. While a State certification is not necessary to work as a Tool & Die maker,

it gives workers more flexibility in employment and is required by some employers.

4. Apprentices usually must be at least 18 years old.

5. People entering this occupation also should be mechanically inclined, able

to work and solve problems independently

6. They should have strong mathematical skills, and be capable of doing work that requires concentration and physical effort.

ADVANCEMENT

a) There are several ways for skilled workers to advance. Some move into supervisory and administrative positions in their firms or they may start their own workshop.

b) Others may take up computer courses and become computer-

controlled machine tool programmers. With a college degree, a Tool & Die maker can go into engineering or Tool design.

PRESENT GLOBAL STATUS OF TOOL AND DIE MAKERS

• About 75% of Tool & Die makers are in manufacturing industries, such as the fabricated metal products, Machinery and Aerospace products and Spare parts industries.

• Rest is self employed in the related field.

BASIC WORKSHOP MACHINES

Radial drilling

machine

Center lathe

Shaping machine

Universal milling

machine

Slotting machine

Planning machine

Horizontal boring

machine

Vertical boring

machine

Universal gear

hobbing machine

Hydraulic hacksaw

machine

Grinding and Polishing Machines

Universal tool &

cutter grinder

Pedestal grinder

Bench grinders / Polishers/Buffers

Abrasive belt

grinders

Surface grinder

Roll grinding

machine

Cylindrical / centerless grinder

PRESS MACHINES

Metal forming press is one of the most commonly used manufacturing machines. Every day, millions of parts are produced by metal forming ranging from battery caps to automotive body panels. Therefore, even a small improvement may add to significant corporative gain.

Currently, the metal forming presses can be divided into two categories:

a) MECHANICAL PRESSES b) HYDRAULIC PRESSES

The former is fast (high speed presses may reach up to several thousand shots

per minute) and energy efficient (the large flywheel eases the impulsive force), but lacks flexibility.

On the other hand, the hydraulic presses are flexible (their motions can be

programmed) and accurate, but are expensive to build and to operate. Recently, there are mechanical presses driven by servomotors.

They could perform as flexible as hydraulic presses with high speed.

Nevertheless, they are even more expensive to build and to operate. FLY PRESS

Fly presses are simple hand devices used for light work. These are extensively

used in small scale industries and need very less space and any unskilled worker can operate with minimum supervision. Fly presses are available in different range of capacity.

Generally, Blanking, Piercing, Notching, V – Bending and L – Bending are

performed using single stage press tools. Bending press is a typical machine applies direct pressure to the material and

forcing it to change shape.

PRESS BRAKE

A brake press is a special type of press machine that bends sheet metal into required shape.

Example:

• Backplate of a computer case

• Brackets

• Frame pieces

• Electronic enclosures

Some press brakes have CNC controls and can form parts with accuracy to a fraction of a millimeter. Machine presses are used extensively around the world for shaping all kinds of metals to a desired shape.

SAFETY ASPECTS

Injuries in a press may be permanent, because of the large forces used.

Bimanual controls (controls the use of which requires both hands to be on the buttons to operate) are a very good way to prevent accidents, as are light sensors that keep the machine from working if the operator is in range of the die.

TOOLS FOR POWER PRESSES

Planishing press has a set of plates with a relief, or depth-based design, in them. The metal is placed between the plates and the plates are pressed up against each other deforming the metal in the desired fashion.

This may be Coining or Embossing or Forming

Punch press is used for forming holes Capping Presses form caps from rolls of aluminium foil at up to 660 per minute. Progressive press tool is a manufacturing method that can involve punching,

coining, bending and several ways of modifying the metal, combined with an automatic feeding system.

The feeding system pushes or pulls a coil of metal through all of the stations of a

progressive stamping die. Each station performs one or more operations until a finished part is made per

the requirements on the print. The final operation is a cut-off operation, which separates the finished part from the parent stock.

The parent stock material that is punched away in previous operations is

considered as scrap metal or skeleton.

Power press with a fixed barrier guard

SHEET ROLLING MACHINE SHEARING MACHINE

PRESS BRAKE CNC BENDING MACHINES

CNC PUNCHING MACHINES

Presses & Hammers (for Sheet Metal and Forging applications)

Hand Fly Press and

Arbour Press

'C' Frame Power

Press

Pillar Type Power

Press

Deep Drawing Press

Screw Press / Forging Press

Mechanical Forging

Hammers

Friction Drop

Hammers

Metal Gathering

Machine / Heating Upsetter

Metal & Sheet Metal Working Machines

Hand Lever Shearing

Machines

Foot Operated Mechanical &

Motorized Guillotine Shears

Billet Shearing

Machine

Universal Sheet

Nibbling

Circle Cutting

Machines

Spinning Lathes

Hand Operated and Motorized Swaging

Machines

Sheet Folding

Mechanical Press

Brakes

Pinch Pyramid Plate Bending Machine, Hand Operated &

Motorized Bending Rollers & Taper

Rollers

Seaming Machines

RO / ROPP Cap Sealing Machine

Machine vice

Section Straightening

Machine

Cut to Length Line

Roll Forming

Machines

Profile Bending

Machine

Tapping - Threading

Machines

Form & Thread

Rolling Machines

Riveting Machine

Pantograph Milling & Engraving Machines

MECHANICAL BLANKING & FORMING PRESSES

General view of a blanking and forming press ADVANTAGES

• More parts are produced

• Improved part dimensional accuracy

• Greater material strength With its blanking and forming presses in this series offers manufacturing systems

that permit cost-effective blanking, drawing, coining, piercing, and calibrating for the production of ready-to-install precision parts in a single operating sequence.

A number of fields - proven modules can be assembled to form application -

specific, customized manufacturing systems. Press models in these series are mechanical presses with modified knuckle-joint drive.

They are available in nominal press forces of 200T up to 1500T and bed

dimensions of 1,500 to 4,000 mm with fixed or adjustable stroke. ADVANTAGES

• High stroking rates even for complex parts • Multiple forming operations in a single press pass • Extreme rigidity of the entire system • Reduced impact speeds to protect dies • Optimized slide motion • Precision, ready - to - install components requiring no subsequent

machining

Die space with progressive die MECHANICAL PRESS LINES

Mechanical press line with feeder automation

ADVANTAGES

1. Automated mechanical press lines ensure efficient manufacturing of medium-size and large panels in production of high volumes.

2. Depending on the number of required forming operations, the lines consist of four, five, or six automated mechanical single presses

3. Advanced mechanical presses offer a long slide stroke and thus permit the manufacture of complex part shapes.

4. Fully automated systems solutions for high - volume manufacturing

5. Fast and reliable component transport with advanced technology

6. Parts of the highest quality thanks to perfected press and bed cushion technology

7. The most advanced automation technology increases production rates

8. High levels of uptime for the lines & Process reliability

Mechanical press line with automation

SHEARING AND ITS ACTIONS DEFINITION

The result of the force imposed on the stock material by the action of the blanking or piercing punch and die is called “Shearing Action”.

These are also related to the effective working and durability of the tool.

The 3 stages of Shearing action are:

1. PLASTIC DEFORMATION 2. PENETRATION 3. FRACTURE

1. PLASTIC DEFORMATION

When the elastic limit of the stock material is exceeded “Plastic deformation” takes place.

A radius is formed on the top edge of the hole and bottom edge of the slug or

blank. The radius is often referred to as “Roll over”.

Load

PUNCH

DIE

MATERIALEDGE RADIUSSTOCK

2. PENETRATION

Punch is forced to penetrate into the stock material and a piece part is displaced into the die opening by a corresponding amount.

Load

PUNCHMATERIAL

DIE

BURNISHED PORTIONON STOCK MATERIAL

BURNISHED PORTION ON

SLUG OR BLANK

STOCK

This is the actual cutting portion of the cutting cycle. Compression of the slug material against walls of the die opening burnishes a portion of the edge of the blank. BRIGHT BAND

At the same time the plastic flow pulls the material around the punch, causing a corresponding “Bright band or Burnished area” in the work material.

The sum of the edge radius depth and the burnished depth is referred to as Penetration. 3. FRACTURE

It is clearly shown in the illustration that further continuation of punch pressure causes fracture to start at the cutting edges of punch and the die. Under proper cutting conditions, the cut edge meets exactly at the breaking lines.

PUNCH

Load

UNDER TENSION

UNDER COMPRESSION

MATERIAL

DIE

BURNISHED PORTION

ON STOCK MATERIAL

BURNISHED PORTION ON

SLUG OR BLANK

STOCK

The edge radius appears more when using soft materials. Highly burnished land

is the result of the material being forced against the walls of the punch and die and rubbing during the final stages of plastic deformation.

The remaining cut portion is the Fractured area or Break.

4. BURR Burr is the projection which appears during fracture. This burr is not preferable, since the breaking lines of both the cutting lines will

not meet each other, resulting in the reduction of the tool life.

BURRBREAK

PENETRATIONEDGE RADIUS

OR CUT BANDBURNISHED LAND

SEPERATED PIECE PART

Space for notes

CUTTING CLEARANCE & ITS EFFECTS DEFINITION

Cutting clearance is the intentional gap provided between the punch and die for

the purpose of separating a piece part from the stock material. It is expressed in Percentage [%]

NATURE OF CUTTING CLEARANCE The cutting clearance depends on the type of

1. STOCK MATERIAL 2. SHEAR STRENGTH OF THE MATERIAL 3. SHEET THICKNESS

A visual check of these characteristics tells whether the punch and die have the proper amount of clearance between them.

PLEASE NOTE: The burr side of a Blank or Slug is always towards the Punch. The burr side of the Pierced opening is always towards the Die opening

This illustration shows the uniform distribution of Cutting clearance between Punch and Die at each side

OPTIMUM OR NORMAL CUTTING CLEARANCE

If the cutting clearance given is sufficient • Burnished area or cut band will be approximately 1/3 (one third) of the

sheet thickness

PIECE PART

(1/3 rd OF SHEET THICKNESS)

DIE

PUNCH

BURNISHED PORTION ON

SLUG OR BLANK

TENSIONAL BURR

EDGE RADIUS

BURNISHED LAND

OR CUT BAND

PENETRATION

BREAK

PUNCH OUTLINE

STOCK MATERIAL

DIE OUT LINE

UNDER TENSION

UNDER COMPRESSION

ON STOCK MATERIALBURNISHED PORTION

OPTIMUM CUTTINGCLEARANCE

OPTIMUM CUTTING CLEARANCE

EXCESSIVE CUTTING CLEARANCE

If the cutting clearance given is Excessive

• Cut band or the burnished area will be less than 1/3 (one third) of the

material thickness • Tensile burr (loose burr) will be more

P IE C E P A R T

D IE

P U N C H

B U R N IS H E D PO R T IO N O N

S L U G O R B L A N K

B U R N IS H E D L A N D

O R C U T B A N D

E X C E S S IV E C U T T IN G

P U N C H O U T L IN E

S T O C K M A T E R IA L

D IE O U T L IN E

U N D E R T E N S IO N

B U R N IS H E D P O R T IO NO N S T O C K M A T E R IA L

U N D ER C O M P R E S S IO N

E D G E R A D IU S P E N E T R A T IO N

B R E A KT E N S IO N A L B U R R

C L E A R A N C EE X C E S S IV E C U T T IN G C L E A R A N C E

( L E S S T H A N 1 / 3 r d O F T H E S H E E T T H IC K N E S S ) INSUFFICIENT CUTTING CLEARANCE

If the cutting clearance given is Insufficient

• More than one cut band

• Breaking lines will not meet each other PIECE PART

(MORE THAN 1/3 rd OF THE SHEET THICKNESS)

BREAK

UNDER TENSION

UNDER COMPRESSION

DIE

PUNCH

BURNISHED PORTION ON STOCK MATERIAL

BURNISHED PORTION ON

SLUG OR BLANK

TENSIONAL BURR

EDGE RADIUS

BURNISHED LAND

OR CUT BAND

PENETRATION

BREAK

DIE OUT LINE

STOCK MATERIAL

INSUFFISCIENT CUTTING

PUNCH OUTLINE

CLEARANCEINSUFFISCIENT CUTTING CLEARANCE

MIS-ALIGNMENT OF PUNCH AND DIE

This is the actual shift between the punch and die which affects the proper cutting of the stock material.

Due to this there will be an irregular cut band appearing on the periphery of the

component.

CHARACTERISTICS OF CUTTING Cutting characteristics indicate whether, the Punch and Die are in perfect

alignment. It also enables him to detect and correct misalignment conditions, when they

occur during assembling the die.

CLEARANCEINSUFFISCIENT CUTTING

PUNCH OUTLINE

DIE OUT LINE

UNDER TENSION

STOCK MATERIAL

DIE

PUNCH

BURNISHED PORTION ON

SLUG OR BLANK

IRREGULAR

UNDER COMPRESSION

BURNISHED PORTIONON STOCK MATERIAL

EXCESSIVE CUTTING CLEARANCE

BREAK

OR CUT BAND

BURNISHED LANDEDGE RADIUS

TENSIONAL BURR

PIECE PART

Hence, proper alignment should be made between punch and die for maximum

tool life.

There are 3 methods commonly used by the tool makers to achieve this. 1. BY USING PRUSSIAN BLUE When the cutting clearance punch and die is very less i.e., ranging from 0.01 to 0.03 mm per side this method is most appropriate.

P r u s s ia n B lu e

2. BY USING SHIM Shims are thin foils of soft metal like copper, brass etc, which are inserted in between punch and die to maintain the cutting clearance.

3. FEELER GAUGE Different thickness and length of checking gauges are available depending on the application. These are used for checking the gap between Punch and Die, after setting them in the die set.

0.1

0.2

0.4

0.5

0.3

3. BY USING SOURCE OF LIGHT This is one more method of aligning the punch and die, where cutting clearance is ranging from 0.03 to 0.08 mm per side.

NOTE: Clearance is expressed in terms of PERCENTAGE (%) per side or

Clearance is expressed in terms of MILLIMETER (mm) per side

DETERMINING CUTTING CLEARANCE There are 3 important methods in practice

1. By referring the standard Cutting clearance chart 2. By using the Formula 3. By using the Thumb rule

1. By referring the STANDARD CUTTING CLEARANCE CHART

Sheet thickness C/2 = Clearance per side in mm

Brass Soft steel Hard rolled

steel Stainless

steel Aluminum

0.25 0.010 0.015 0.020 0.010 0.020 0.50 0.025 0.030 0.035 0.020 0.050 0.75 0.040 0.045 0.050 0.040 0.070 1.00 0.050 0.060 0.070 0.050 0.100 1.25 0.060 0.075 0.090 0.060 0.120 1.50 0.075 0.090 0.100 0.070 0.150 1.75 0.090 0.100 0.120 0.090 0.170 2.00 0.100 0.120 0.140 0.100 0.200 2.25 0.110 0.140 0.160 0.110 0.220 2.50 0.130 0.150 0.180 0.120 0.250 2.80 0.140 0.170 0.200 0.140 0.280 3.00 0.150 0.180 0.210 0.150 0.300 3.30 0.170 0.200 0.230 0.160 0.330 3.50 0.180 0.210 0.250 0.170 0.350 3.80 0.190 0.230 0.270 0.180 0.380 4.00 0.200 0.240 0.280 0.190 0.400 4.30 0.220 0.260 0.300 0.210 0.430 4.50 0.230 0.270 0.320 0.220 0.450 4.80 0.240 0.290 0.340 0.230 0.480

5.00 0.250 0.300 0.360 0.240 0.500 Space for notes

2. By using the FORMULA C/2 = 0.01 X t X √ fs Where, C/2 = Cutting clearance per side

t = Sheet thickness in mm fs = Shear strength of the stock material in kg /mm2

SHEAR STRENGTH CHART

Material Shear strength (fs) in kg/mm2

Soft Hard

Steel with 0.1 % C 24 32

“ 0.2 % C 30 40

“ 0.3 % C 36 48

“ 0.4 % C 45 56

“ 0.6 % C 55 72

“ 0.8 % C 70 90

“ 1.0 % C 80 105

Stainless steel 50 56

Silicon steel 45 55

Steel deep drawing quality 30-35 -

Aluminum A 1 99 & 99.5 7-9 13-16

Aluminum alloy A1 – Cu – Mg 22 38

Bronze rolled 32-40 40-60

Brass 63 & 72 22-30 35-40

Copper 18-22 25-30

Tin 3 4

3. By using the THUMB RULE Clearance can also be calculated in Percentage [%] of Sheet thickness:

C/2 (CLEARANCE PER SIDE) Sl. No. Material Percentage of Clearance

1 Brass 5% 2 Soft steel 6% 3 Hard steel 7%

4 Stainless steel 5% 5 Aluminum 8 – 10%

NOTE: 1. Pierced hole is getting the dimension of the PIERCING PUNCH. Hence, the clearance should be added to the die opening. 2. Blanked component is getting the dimension of the BLANKING OPENING or DIE. Hence, the clearance should be subtracted on the Blanking punch.

Example: Material: Steel with 0.3% Carbon

Shear strength (fs) = 45 kg/mm2 Sheet thickness (t) = 1.75 mm

Component: Dimension of the Piercing punch = Ø15.00 mm Dimension of the Die opening =15+ (2 X C/2) (From the table C/2 = 0.10 mm) = 15 + (2 X 0.1) = 15 + 0.2 = 15.20 mm Dimension of the Die opening = Ø15.20 mm Dimension of the Blanking punch = 35 – (C/2 X 2) (From the table C/2 = 0.10 mm) = 35 – (0.1 X 2) = 35 – 0.2 = 34.80 mm Dimension of the Blanking punch = 34.80 mm x 34.80 mm Dimension of the Blanking die = 35.00 mm x 35.00 mm

SHEAR FORCE & ITS APPLICATIONS

Shear force is the force required to separate a piece part from the stock material with plain punches.

It is expressed in terms of Tonne.

This force is also required to determine the thickness of various plates necessary in the construction of the tool and for selecting the appropriate press.

SHEAR STRENGTH

It is the strength required for producing fracture in the plane of cross section, when acted on by the SHEAR FORCE.

Shear strength is expressed in Kg/mm2

TENSILE STRENGTH

The tensile or ultimate strength is the strength, corresponding to the maximum load reached before rupturing the specimen.

It is also expressed in Kg/mm2

FORMULA USED TO DETERMINE THE SHEAR FORCE

K x L x S or (fs) x t F = ------------------------------ = …….. Tonne

1000 Where,

F = Shear Force K = Constant value 1.3 (Because sheet thickness will not be uniform) L = Total length of cut in mm. S or (fs) = Shear strength in Kg/mm2. T = Thickness of the stock material in mm. 1000 = To convert kg to Ton

PRESS SELECTION VALUE It is the value which is very much helpful in choosing an appropriate press for

successful production and efficient working of tool. PRESS SELECTION VALUE

(Fp) = F + 20% of F, Where, F = Shear Force

METHODS OF REDUCING THE SHEAR FORCE Sometimes availability of press capacity may be slightly less than the required

tonnage. To overcome from this problem there are two effective methods in practice. 1. By providing shear angle on the cutting punches 2. By varying the height of the cutting punches (Staggering the punches)

1. SHEAR ANGLE

It is the angle provided on the cutting face of either punch or die to reduce the shearing force as shown in the illustration.

Advantage of Shear angle: By providing this angle the punch or die will gradually come in contact with the layers of the stock material and cutting or shearing action will be performed layer by layer.

This method is limited to secondary importance components as the cut edge will not be good, compared to normal shearing operation.

1t1t

1t

1t

1t

1t

not flat Component is

at an angleCut edge is component

Dished(flat)componentNormal

at an angleCut edge is

SHEAR ANGLE PROVIDED ON DIESHEAR ANGLE PROVIDED ON PUNCH

2. STAGGERING

This is one more method of overcoming from the problem of shearing. After assembling the punches with top unit, grind all the cutting punches to one level.

Select a set of punches in such a way that the load required to cut will be equal to the other set of cutting punches. Reduce the height of one of the sets at least by one stock thickness.

Staggering

Punches fixedin punch holder

By this method one set of punches will start shearing the material and other set will come in contact with the stock material only after the completion of the operation performed by the previous set of punches.

Hence, whenever this method is adopted in the tool, there will be two IMPACT

CUTTING SOUND, which can be heard very clearly. This method of varying the punch height is called as “Staggering”.

Space for Notes

CUTTING OPERATION IDENTIFICATION OF OPERATIONS BLANKING: Cutting the outer contour of a piece part. After completing all the

remaining operation, it is called as “COMPONENT”.

PIERCING: Hole originated within the piece part. Any geometrical profile of hole

can be pierced.

NOTCHING: Partial cutting is done at the side of the stock strip. Usually,

notching operations are done to simplify the blanking profiles.

SIDE NOTCHING

CUT-OFF: Single line cutting without Scrap Bridge. Produced components are of secondary importance. Usually, used to produce commercial components with maximum economy on tool cost

PART-OFF: Double line cutting producing scrap normally equal to the value of one

scrap bridge.

TRIMMING: Secondary operation carried to redefine the contour of the

component. Usually Drawn cups and Die cast components are trimmed to remove the excess material appeared during the production.

SHAVING: Secondary operation performed on pre blanked components to

resize the dimensions and achieve higher accuracy.

This operation produces smooth surface on the periphery of the component through its thickness

SIDE PIERCING: Usually, this is a secondary operation performed on drawn cups.

Cups of required shape and size are drawn followed by cam piercing.

DINKING: Components from fiber material like Nylon, Plastics, Rubber, Fiber glass,

Printed circuit boards (PCB) etc, are produced with this operation. Blanking punch is the only member which is employed for cutting the contour. Piercing is done as usual with punch and dies. The cutting face of the piercing punch is made as concave profile.

NON – CUTTING OPERATION

IDENTIFICATION OF OPERATIONS BENDING: Bending is performed on pre-cut sheets or blanks to obtain a required

angle. It is done in straight axis. General bending profiles are L – Bending, U – Bending, V – Bending and Z-Bending. Usually, Bending has to overcome both “Tensile stresses” as well as “Compressive stresses”. When Bending is done, the residual stresses make it re-bend or spring back towards its original position, so we have to over bend the sheet metal keeping in mind the residual stresses.

FORMING: Any profile with curves can be formed with proper study of material

behavior. Materials must posses’ good ductility and deep draw quality. Forming takes place in a curved axis.

CURLING: More than 3/4th forming in a continuous curvature is referred to as

Curling. This operation is divided into

a) Pre curling. b) Final curling

Material must be soft enough to accept the severity of the forming. Hence, deep draw and extra deep draw quality materials are preferred. Usually, this is employed for the production of hinges for links, to the components which need fulcrum points etc.

FLANGING: Sometimes it is also referred to as “Extruding”. Many methods are used in this operation.

1. Flanging without pre pierced hole 2. Flanging with pre pierced hole 3. Flanging with pre pierced hole located by the punch pilot

The height of the flange depends on the diameter of the pre-pierced hole.

DRAWING: Cylindrical or Rectangular or Square cups are produced with this

operation. Material undergoes severe strain and flow into the die from all the directions. Hence, it must have maximum tensile strength and yielding capability.

COINING: The material will experience maximum strain, because of squeezing. The die halves are pressed against the material, which is sandwiched and forced to accept the inner profile of the die.

Coining requires higher tonnage than any other press operation.

STAMPING: Punch profiles are directly transferred on to the work piece.

Depressed profiles to a certain depth are possible with this operation.

EMBOSSING: Sheet metal surfaces can be depressed to a depth till it tears. Hence,

before the material selection “CUPPING TEST” has to be conducted. In this operation thinning does not take place.

MATERIALS AND THEIR PROCESS

Different materials are very essential to construct the tool and production of

components. Materials are divided into two main groups.

1) Steel material for the construction of the tool 2) Sheet material for the production of component

1) STEEL MATERIAL FOR THE CONSTRUCTION OF THE TOOL The construction of tool involves various types of steel material. It depends on the function of the part in the tool.

Usually, HCHCr, OHNS, St-42, Mild steel (MS) and 17Mn1Cr95 materials are used.

TOOL MATERIAL AND ITS IS: CODIFICATION

Sl. No. Material IS: Codification

1. HCHCr: High Carbon High Chromium steel T215 Cr12 W90

2. OHNS Oil Hardened Non – Shrinkable steel T110 Cr1 W2

3. St–42 Steel with 0.42% Carbon 4. MS Mild steel

5. LCS Low carbon steel or Case hardening steel 17Mn1Cr95:

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A brief description is given below about the material and the tool element. 1. Die and Punch for cutting operation -------------- HCHCr (T215 Cr12 W90) 2. Die and Punch for Non-Cutting operation -------- OHNS (T110 W2 Cr1) 3. Punch Back plate ------------------- OHNS or 17MN1CR95 4. Die Back plate ---------------------- OHNS or 17MN1CR95 5. Punch plate ------------------------- Mild steel (MS) 6. Stripper plate ---------------------- Mild steel (MS) 7. Stripper insert --------------------- OHNS 8. Guide plate ------------------------ Mild steel (MS) 9. Strip support plate---------------- Mild steel (MS) 10. Top plate --------------------------- Mild steel (MS) or Cast iron 11. Bottom plate ---------------------- Mild steel (MS) or Cast iron 12. Shank ------------------------------- Mild steel (MS) 13. Guide Bush and Pillar ------------ OHNS 14. Tie bar ----------------------------- Mild steel (MS)

1. HIGH CARBON HIGH CHROMIUM STEEL (HCHCr)

These are specifically used for cold working press tools and oil hardened up to 60-62 HRc.

The chemical composition:

a) 2.15% Carbon, b) 0.9% Tungsten c) 12% Chromium d) Small percentage of Silicon and Manganese.

These materials are best suited for cutting dies and punches, as they retain the

cutting edges for a longer period. 2. OIL HARDENED NON-SHRINKING STEEL (OHNS)

These steels consists a) 1%-2% Carbon b) 4%-12% Chromium

Oil hardened upto 60-62 HRc. But for non-cutting operations 56-58 HRc is quite

sufficient. 3. MILD STEEL (MS) and St-42

These are used for most of the parts in press tool, mould box, jigs and fixtures. Mild steel contains

a) 0.3% Carbon b) 0.1% - 0.8% Manganese.

Example: Steel En2. This steel can also be case carburized and hardened upto

54-56 HRc.

Free cutting Steel like “En” contains less than 0.15% carbon and cannot be hardened.

4. CAST IRON (C.I)

Cast iron contains 2.25 - 2.75% carbon and can absorb vibrations well and suitable for bases, machine beds and bodies of fixtures. These have self lubricating properties, hence also suitable for machine slides and guide ways. 5. 17Mn1Cr95

These are case hardening steels have good toughness and cost saving. Used where there is no movement of parts and needs good support for the other tool elements.

As the percentage of carbon in the material is not sufficient for hardening process

the case must be enriched with carbon by carburizing process. A case depth of 0.5 to 0.7mm is achieved by a prolonged period of 4 to 5 hours.

2) SHEET MATERIAL FOR THE PRODUCTION OF COMPONENT Many types of sheet materials are used for the production of components.

Namely, Non – Conventional materials

a) Plastic coated paper b) Thin plastics c) Poly-fibres d) Corrugated sheets e) Printed circuit boards (PCB) f) Tablet strips

Conventional materials

1. Steel – CRCA (Cold Rolled Close annealed) D – Quality (Draw quality) DD – Quality (Deep Draw Quality) EDD – Quality (Extra Deep Draw Quality)

2. Brass – 1/4th hard, Half hard, 3/4th hard and Full hard 3. Copper - 1/4th hard, Half hard, 3/4th hard and Full hard 4. Phosphor bronze -1/4th hard, Half hard, 3/4th hard and Full hard 5. Aluminum – 1/4th hard, Half hard, 3/4th hard and Full hard

2A) FINISHING OPERATION OF COMPONENTS

a) VIBRATORY FINISHING GUIDE

In vibratory finishing, energy in the form of vibratory forces is transformed by the machine's drive system into a mass of loose media and then into the parts.

The entire load is in motion at same time so that the media act against the parts throughout the complete mass.

Producing good surface finishes using barrel finishing depends on the right selection and use of tumblers, abrasives, lubricating agents, carrying agents and polishing agents.

Barrel finishing, also known as “Barrel tumbling”, is a surface improving

operation in which a mixture of parts, media and compounds are placed in a six- or eight-sided barrel and rotated at a predetermined speed for the purpose of rounding corners, de-burring, grinding, de-scaling, de-flashing, improving surface finish, burnishing, polishing and radiusing parts in bulk.

It works by tumbling parts in a rotating barrel, thus creating friction by tumbling

parts against each other and against other materials, such as media and compounds. Tumbling Highlights

• Parts can be finished less expensively than by hand. • Many parts can be processed at one time.

• Requires very little handling.

• Parts are tougher and stronger after tumbling

• Tumbling provides a certain amount of stress relief

• Forgings and castings can be blended

• Machine parts and stampings can be deburred and burnished to a high finish

• On long runs, the systems can run overnight

• Careful and proper machining of your parts will save tumbling time

MATERIAL WEIGHT CALCULATION

DEFINITION 1. WEIGHT

It is the sum of the volume and the specific gravity of the material. Weight is expressed in Kgs. Value of Specific gravity for each material varies depending on the density of molecules in it. CALCULATION:

Volume X Specific Gravity Weight =--------------------------------------- =-------- Kg

1000000

V X Sp. Gr. W =-------------------=------------- Kg

1000000

Where, W = Weight of the material in Kg V = Total volume of the material in mm3

Sp. Gr. = Specific gravity in Kg/mm2

Volume of the Flat material =L X B X t

Where, L = Length of the material in mm

B = Width of the material in mm T = Thickness of the material in mm

∏ X D2 Volume of the Round material = ------------- X t

4 Where, ∏ = 3.1416

D = Diameter of the material in mm t = Thickness of the material in mm

SPECIFIC GRAVITY CHART

Material Specific gravity gm/Cm3

Steel 7.85

Cast steel 7.85

Grey cast iron 7.2

High speed Steel 9.0

Hard metal H1 14.75

Invar (36% Ni) 8.7

Brass (Ms 60) 8.5

Al bronze 8.4

Al cast bronze 7.6

Tin bronze 8.6

Lead bronze (Pb Bz 25) 9.5

Al cast bronze 2.8

BASIC CONSTRUCTION OF THE TOOL 1. Die and Punch for cutting operation -------------- HCHCr

2. Die and Punch for Non-Cutting operation -------- OHNS

3. Punch Back plate ------------------------- OHNS or 17Mn1Cr95

PUNCH BACK PLATE

Material = OHNS

A A

4. Die Back plate ---------------------- OHNS or 17Mn1Cr95

Material = OHNS

A A

DIE BACK PLATE

5. Punch plate -------------------------Mild steel (MS)

6. Stripper plate ---------------------- Mild steel (MS)

SECTION-AA

A

A

7. Stripper insert --------------------- OHNS

SECTION-AA

A

A

8. Guide plate ------------------------ Mild steel (MS)

9. Strip support plate---------------- Mild steel (MS)

SECTION-AA

10. Top plate --------------------------- Mild steel (MS) or Cast iron

Material = St-42

TOP PLATE

SECTION-AA

A

A

11. Bottom plate ---------------------- Mild steel (MS) or Cast iron

Material = St-42BOTTOM PLATE

SECTION-AA

A

A

12. Shank ------------------------------- Mild steel (MS)

13. Guide Bush and Pillar ------------ OHNS

14. Tie bar ----------------------------- Mild steel (MS)

SECTION-AA

15. Die set and its types

1. Diagonal pillar dies set 2. Rear pillar or Back pillar die set 3. Center pillar die set 4. Four pillar die set

Thread for fixing the Shank

Guide pillar

plate

Top

Bottom plate

Guide bush

H7/j5

H7/h6

SHUT HEIGHT OF THE TOOL

H7/p6

SECTIONAL VIEW OF A STANDARD DIE SET

PROGRESSIVE STAMPING DIE

Progressive die with strip and punching

A progressive stamping die is one of the types of press tools, designed and built to convert a flat strip of metal into parts that conform to component specifications.

FUNCTION OF PROGESSIVE TOOL

The die is mounted on a suitable press. As the ram moves up, the punch unit opens and closes when the press moves down.

The stock material is fed through the die while the die is open to a precise amount with each stroke of the press.

When the punch unit is brought down, the tool performs its work on the sheet metal. Due to this action one or more completed piece parts will fall down through the opening in the bottom plate.

These dies can modify the stock metal into different shapes like Bending, Embossing, Drawing, Forming, Horning, Extruding, Coining, and Punching. Different hole profiles is possible to cut in the stock metal.

Since additional work is done in each stage of the die, it is important that the strip be advanced very precisely, so that it aligns within accurately as it moves from station to station.

ROLE OF PILOTS

DEFINITION Pilots are non-cutting male members, mounted usually in the punch holder for re-registering the pre-pierced hole for consecutive stations especially in progressive tools. These are made with good tool steel material that is OHNS (T110 W2 Cr1) and hardened up to 56-58 HRc. These pilots are also available readily (material used is HSS) in the market with standard diameter and length. Function of a Pilot: The function of a pilot is to position the stock strip accurately and bring it into proper register for successive stations.

Bullet shaped or conical "pilots" enter previously pierced round holes in the strip to assure this alignment, since the feeding mechanism usually cannot provide the necessary precision in feeding.

VARIOUS OTHER TYPES OF PILOT NOSE PROFILES

TYPES OF PILOTS

BULLET NOSE PILOT

FLAT ACCORN PILOT

RECTANGULAR PILOT

CUT-OFF PILOT

CONICAL STUB NOSE PILOT

PILOT NOSE CORNER

RADIUS

ROLE OF STOPPERS

DEFINITION Stoppers are stopping agents, fixed or engaged on the die to arrest the feeding movement of the stock strip. This is the location of the actual stopping point or stage against which the stock is halted.

TYPES OF STOPPER

Sl. No. Name of the stopper Sketch

1 Solid stopper or Solid stop block

Butting surface

SolidStopblock

2

Pin stopper

a) Plain pin

b) Headed pin

3 Side or stage stopper

4 Trigger stopper

Heeled punches Specially, the illustrated punch is a notching punch. However, principles relating to the heel function will be much the same for other punches as well. Here, the heel is made in a manner commonly used in progressive dies. The nature of the notching operation is such that, cutting force at the front of the punch is unopposed and thus tends to displace the punch away from the front cutting edge. Partial notching will tend to displace the punch in a direction parallel to the feeding. The purpose of a heel is to support the punch by resisting displacement. This type of heel is an integral boss extending beyond the working face of the punch.

Partial cutting punch with Heel

HEEL

SCRAP

Prim

ary strip width

Secondary strip width

The heeled portion is made a sliding fit in the die opening on three sides. Therefore, the heel affords lateral thrust resistance along any displacement included within the three directions. Pitch punch Pitch punches are cutting punches used in the progressive tools for accurate feeding of the strip. These are made of good Tool steel material i.e. (T215W90Cr12) HCHCr and hardened up to 60-62 HRc and ground to the exact size equal to PITCH. These punches are suitable for sheet thickness less than 2 mm. Pitch punches are placed in the very first stage of the operation. These are also called as “Partial cutting punches” for the reason that they cut only a portion of the side of the stock strip which is exactly equal to ONE PITCH.

Since pitch punches cut only a portion of the side of the stock material. Due to this cutting action is imbalanced which deflects the punch resulting in punch breakage. Hence, heels are provided behind the cutting edge to support the pitch punch.

thickness

0.5xSheet

R2(TYP)

M5 0r M6

x 20mm deep 2xscrap+2mm5to6mm

45.0°

a

f

b

Pitch punch with HEEL

Secondary strip width

Primary strip width

SCRAP

HEEL

VALUES FOR SIDE SCRAP AND SCRAP BRIDGE

Sheet thickness in mm

Component horizontal width in Millimeters Upto 10 10 – 50 50 -100 100 -150 150 - 250

0.5 1.5 2.0 3.0 3.5 4.0 1.0 1.0 1.75 2.0 2.5 3.0

1.5 1.5 2.0 2.5 3.0 3.5 2.0 2.0 2.5 3.0 3.5 4.0

2.5 2.0 3.0 3.5 4.0 4.5

3.0 2.0 3.5 4.0 4.5 5.0 4.0 2.5 4.0 4.5 5.0 5.5

5.0 3.0 4.5 5.0 5.5 6.0 6.0 3.5 5.0 5.5 6.0 6.5

7.0 4.0 5.5 6.0 6.5 7.0

8.0 5.0 6.0 6.5 7.0 8.0 9.0 6.0 7.0 7.5 8.0 9.0

10.0 7.0 8.0 8.5 9.0 10.0

Out sideInsidestep headedstop pin

step headedstop pin

Outside step headed stop pin

Die plate

Stripper

NON – CUTTING OPERATION IN DETAIL INTRODUCTION

Present day calls for lots of innovative products which essentially require good knowledge of tooling.

Mechanical, Electrical, Electronic and Automobile industries need products

having verities of profiles for different applications. Non - cutting operations are those which shape the flat blank to the required

profile. In these operations material undergoes severe strain and needs very good

knowledge about the material property, behavior, strength and its limitations. In many tools these operations are integrated depending on the size of the

component.

Examples of products for Non – Cutting operations

1. Pressure cooker 2. Pressure pan 3. Utensils 4. Contacts and Relays 5. Heating elements 6. Computer hardware

TYPES OF NON - CUTTING PRESS TOOL OPERATIONS

NON – CUTTING

1. FORMING 9. COINING

2. BENDING 10. STAMPING

3. DRAWING 11. IRONING

4. CURLING 12. PLANISHING

5. FLANGING 13. SWAGING

6. DIMPLING 14. EXTRUDING

7. EMBOSSING 15. BULGING

8. HORNING

HYBRID

1. LANCING

2. LOVRING

7. Electrical appliances 8. Gear box cover 9. Automobile parts – Doors, Bonnet, Wheel

drums Clutch plates etc., 10. Aviation and Space components

It is the basic behavior of material. Whenever a sheet metal deformed and an external loading is unloaded, it will be restored to its initial state i.e., after unloading nothing in the state of structure remains of the previous condition. CHARACTERISTICS OF MATERIAL This unique character of the material is most useful in sheet metal fabrication because most products of sheet metal press work are not flat components that can be produced by die cutting operations alone. They generally have a third dimension obtained by a shaping operation, which can be performed in the same die as of the cutting operation or in a separate die. Shaping operations are generally divided into three groups.

GROUPS OF

NON – CUTTING

DIES

BENDING FORMING DRAWING

TYPES OF OPERATIONS IN NON-CUTTING DIE GROUPS

BENDING 1. WIPING 2. AIR-BEDING 3. OBTUSE ANGLE

BENDING 4. ACUTE ANGLE

BENDING 5. L-BENDING 6. U- BENDING 7. V- BENDING 8. Z-BENDING

FORMING 1. FLANGING 2. COINING 3. SWAGING 4. BULGING 5. NECKING 6. CURLING 7. HORNING 8. EMBOSSING 9. FLARING 10. STAMPING 11. EXTRUDING 12. NIBBLING

DRAWING 1. SQUARE CUP 2. RECTANGLE CUP 3. TRIANGLE CUP 4. CONE CUP 5. SHALLOW CUP 6. DEEP DRAW CUP 7. FLANGED CUP

1. BENDING Bending is shaping the material around a STRAIGHT AXIS, which

extends completely across the material. One or more bends may be involved in the bending dies.

These dies are important class of press tools. The sheet material flow in these tools is always uniform and its thickness

remains unchanged. TYPES OF BENDING

a) L – Bending b) U - Bending c) V – Bending d) Z – Bending

V-BEND INGU-BENDING

L-BEND ING

Z-BEND ING

NEUTRAL PLANE AND ITS IMPORTANCE

(SQUEEZED)

(STRETCHED)

DIEof bendOutside

Inside of bend FORCE

Neutr

al pla

ne

Neutral plane is an imaginary plane exists between the area under tension and the area under compression. The neutral plane always moves towards the inner surface at a distance of one-third (1/3) to one-half (1/2) the thickness of the material.

EFFECT OF GRAIN DIRECTION DURING BENDING DEFINITION The particle chain in the sheet material is called “Fiber” and these fibers are arranged parallel to each other and called as “Grain direction”. In bending operation the grain direction should be considered for effective bending of the component. CONDITION OF GRAIN DIRECTION IN BENDING

The Grain direction should always be perpendicular to the bend axis. Bending will not be effective and bent portion will not be strong, when the axis of bend is parallel to the grain direction. DETERMINING THE FLAT LENGTH BY BEND ALLOWANCE METHOD

Where,

B. A = Bend allowance [Arc length of neutral axis] in mm Θ = Bend angle in degrees IR = Inside radius of bend in mm t = Sheet metal thickness in mm K = Constant for neutral axis location K = 0.33 when IR is less than 2t K = 0.50 when IR is more than 2t

DEFECTS IN BENDING 1. SPRING BACK After bending operation if the pressure is released, elastic stresses remaining in the bend area will cause a slight increase in the bend angle. Material movement of this type is known as “SPRING BACK”.

Θ x Π (IR + Kt) B A = ---------------------

180

SPRING BACK

UNDER LOAD

SPRING BACKBENDING RETAINED

2. THINNING This defect occurs when there is misalignment and axial deflection between the punch and die. If the clearance between punch and die is less than the sheet thickness, results in the elongation of side wall of the component.

THINNED AREA

METHODS OF PREVENTING SPRING BACK A) Over Bending in V-bending and Air-bending dies B) Corner setting or Coining in V–bending and U - Bending A) OVER BENDING In this method the blank is bent to a lesser angle than required and the blank is spring back to the required angle. DIFFERENT METHODS OF OVER-BENDING

CASES SKETCH

1. Over bending in a V-bending die is accomplished by under sizing the punch to 880.

90.0°

90.0°

Punch88°

Die

Component

2. In a single L or U-bending die clearance between punch and die must be slightly less than the sheet metal thickness and punch must be under sized to 880. pad

90.0°88.0°Die

Punch

Pressure

Component

3. In this case the punch is made to 900 but the bending die is under sized to 880 and clearance provided between punch and die is less than the sheet thickness.

Punch

Die

88.0°

Pressure pad

4. In this case both punches are under sized to 880 to allow the component to achieve 900

88.0°

Punch

88.0°

Pressure pad

Movableside punch

B) CORNER SETTING In this method the metal is squeezed slightly in the corner in order to relieve elastic stresses. This method is also known as ‘Coining or Squeezing’. The punch nose is modified for corner setting operation. When the punch is bottomed pressure builds up rapidly.

REMEDIES SKETCH

1. Squeeze the intersection points to retain the bent angle permanently.

2. Bottoming is done by squeezing the bent area to retain the bend after releasing the load.

Die

Punch

90.0°

Punch

Detail-AA

88°

BENDING FORCE It is the amount of force required to bend and give a desired shape to the piece part. It depends on the sheet thickness, die opening factor, length of bend and the amount of bottoming or ironing used. FORMULA TO DETERMINE BENDING FORCE K X SU X W X t2

FB = ------------------------ L Where, K = Die opening factor (0.33) L = Length of bend (rd + rp + C) rd = Die radius rp= Punch radius C= Die clearance Su= Ultimate tensile strength in kgs/mm2 t = Sheet thickness W = Width of the component or stock material Where, K is 0.33, when the die opening is less than [<] 5 times the thickness, 0.667 when the die opening is 5-10 times the thickness and 1.20 when the die opening is 10-16 times the thickness.

Pressure pad force FP = 0.5 x FB

Total force required = FP x FB

2. FORMING

The operation of forming is similar to bending except that the line of bend is along CURVED AXIS instead of a straight one. The metal flow is not uniform. Forming dies transfers more complex forms to sheet metal components.

3. DRAWING

In draw tools, flat blank is transformed into a cup or shell. The parent material is

subject to severe plastic deformation.

4. HORNING

Horn dies are provided with an arbor or extended horn over which the parts are

placed for secondary operations such as Seaming.

Horn dies may also be used for piercing holes in the sides of shell.

5. CURLING

It is an operation of rolling the edges of the sheet metal into a curl or roll. The

purpose is to strengthen and provide a protective edge. Example: A hinge in which both members are curled to provide a hole for

inserting the hinge pin.

Pre-curling

Component with Pre-curling

Uniform curve

Good qualitycomponent

Deformed component Inferior

qualitycomponent

Componentwithout

Final radius

2

1

4

3

5

6

6

5

3

4

2

1

6. BULGING

Bulging is an internal forming operation used to expand portions of a drawn shell

or tube. The bulging force is applied from inside the tubular structure which transmits through a medium that will flow, but does not compress.

Most common Medias are rubber, urethane, bulging oil or water. This presses and expands the walls of a cup, shell or tube with an internal expanding segmental punch or compressed air or liquids or semi liquids, such as waxes or tallow of rubber and other elastic materials.

After

Before

Before

After

BULGING DIE USING LIQUID MEDIUM

Cross section of the component

After bulging

Before bulging

MEDIA

LIQUID BULGING

CYLINDRICAL TUBE

PARTING SURFACE

RUBBER SEALGASCKETO-ring

PLUNGER

SPLIT DIE

SPLIT DIE

In the case of using bulging oil as bulging media gaskets must be fixed in between the two halves of the die to prevent leakage of oil. Otherwise the pressure of the oil cannot be controlled and which may result in the variation of the shape and size of the component. BULGING MEDIUMS Urethane is commonly used because it is more resistant to abrasion, tears and cuts and is superior to oil and grease. This is clean, easy to use and either made to order or readily available. Grease, oil, water are used only when shape of work piece prevents the use of urethane. The piece part is filled with liquid medium in the die cavity. Since time consuming is more, this is used for limited production. 7. SWAGING

The operation of swaging sometimes is called ‘NECKING’, and exactly opposite to bulging.

When a work piece is swaged, a portion is reduced in size and this causes the work piece to become longer than it was before swaging.

BeforeAfter

8. EXTRUDING

This is a special process to manufacture collapsible tubes, shells etc. The blank is also called as “Billet” which is loaded in the die is forged upwards or downwards under a high pressure between punch and die.

The amount of clearance between punch and die determines the wall thickness

of the extruded shell.

After

Before

BILLET

EXTRUDED PART

9. FLANGING (Flaring)

The process of forming an outward protrusion (flange) in a piece part is called

“Flanging”.

It is performed particularly for creating threads, inserting guide pins for further assembly.

Flanging is done in stage tool as well as progressive tools with pre piercing or

direct flanging with hybrid punches.

DIERADIUSRADIUS

DIE

PUNCH WITH PILOTDIRECT FLANGING

FLANGING WITHOUT PILOT

PRE PIERCING

DIERADIUS

FLANGING PUNCH

PUNCH

(WITH HYBRID PUNCH)FLANGING WITHOUT PRE PIERCING

PRE PIERCING

10. DIMPLING

A forming die which produces a conical flange (stretch flange) encircling a hole in

one or more sheets of material.

Dimpled projection

11. COINING

In coining metal flows and occupies the space between two halves of the die

suffering too much of strain in cold state. Hence it is also called as “Cold forming”.

12. IRONING

An operation in which the wall thickness of the drawn shell or bent component

reduced intentionally and then its surface is smoothened.

t

TIroned surface

13. EMBOSSING

It is a process which produces relatively shallow indentation or raised deformation with theoretically no change in the material thickness.

Embossing is also used as locater for springs in certain electrical assembly so

that the spring is not displaced during working.

DIEDIE

PUNCH PUNCH

A B

Projection

Depression

14. PLANISHING OR PLANNING

It is an operation done to flatten dished components produced by conventional

press tools. There are two types of planning in practice. 1) First method: Between two hardened plain blocks dished components are

placed and pressed with sufficient pressure. 2) Second method: Components are placed in between two hardened blocks

having diamond projected points as shown in figure and pressed. In this operation the drawback is indentation marks which appear on the

components. But this method is most effective in relieving the internal stresses that may induced due to many reasons.

planished componentCross section of a

PLANNING DIE

PLANNING DIE

PLANNING DIE

PLANNING DIE

PLANNING DIE

15. ASSEMBLY PRESS OPERATION

These press operations are done for assembling the sheet metal components

together with rivets. Two or more number of components placed in position as per the requirement

and rivets are inserted in the pierced holes. Then all these are placed in the tool between punch and die and pressed till rivets gets bulged and perfectly holds the parts.

This unit is called as “Sub-assembly”. The pressure on the rivets can be easily

controlled by placing setting blocks in the tool.

Rivets

Assembly press operation

DRAW OPERATION BASIC FUNCTION OF A DRAW TOOL To produce a cylindrical cup a round flat blank (cut from flat strips) is placed on the draw die, the punch pushes the blank in to the die by the application of an external force. During the return stroke, cup is removed by the counter bore made in the bottom of the die.

DRAW OPERATION WITHOUT BLANK HOLDER

Drawn cup

Blank locator

Air vent

Flat blank

Die

Punch

DRAW OPERATION WITH BLANK HOLDER

Drawn cup

Air vent

Flat component

Die

Punch

Blank holder

AIR VENTS During the operation the punch tries to push the blank material into the die. At this time, the air in the draw die has no way to escape. This leads to rupture of the component. Hence, a small diameter through hole is drilled in the punch & die, to allow the entrapped air to escape. CLEANING OF AIR VENT HOLE During continuous production of components, the air vent often gets blocked. This is because of continuous use of lubricants. Hence, it is advised to clean the air vent hole frequently by blowing out the foreign substances with compressed air. PUSH THROUGH DRAW DIE A simple draw operation is shown in the following illustrations. A round flat blank cut from flat strip is placed on the die face and punch pushes the blank in to the die. On the return stroke the cup is stripped by the counter bore in the die. This operation is known as “Shallow drawing” and die is called as “Push through die”. DRAW OPERATION WITHOUT BLANK HOLDER

Drawn cup

locator

Air vent

Flat blank

Die

Punch

Blank

DRAW OPERATION WITH BLANK HOLDER

Drawn cup

Air vent

Flat component

Die

Punch

Blank holder

DRAW OPERATION WITH RIGID BLANK HOLDER

Drawn cup

Air vent

Flat component

Die

Punch

Blank holder

Drawn cup

1. SHALLOW DRAWING Operations where the depth is less than half the cup diameter the operation is also called as “Shallow drawing”. Note:

Shallow drawing: Where, depth of cup is less than half the cup diameter. Example: Plates, Shallow pans etc., 2. DEEP DRAWING The drawing of deeply recessed parts from sheet material through plastic flow of the material when the depth of the recessed equals or exceeds the minimum part width is known as “Deep drawing”. Deep drawing is drawing a cup whose depth is more than half the diameter of the cup. Note:

Deep drawing: Where, depth of cup is more than half the cup diameter. Example: Pressure cooker bottom, Cups, Washing machine tubs etc.,

Drawn cup

HeightDepth

Drawn cup

Height

Depth

DETERMINING THE FLAT BLANK DIAMETER Flat blanks are the previous shape of the material in any draw operation. These are produced from cutting press tools, usually blanking tools and used for the production of drawn components.

A

B C E

D

Drawn cup

Flat blank

h1

PROCEDURE:

1. Draw an arc C-D with B as centre and BC as radius 2. Draw an arc D-E with A as centre and AD as radius, which bisects the line

BC produced at E 3. The length B-E gives the radius of the blank

DETERMINING THE FLAT BLANK DIAMETER OF A DRAWN CUP BY ALGEBRAIC METHOD

Drawn cup

The Drawn cup consists:

Cylinder

Flat bottom

Ød1

Ød

Ød2

h

h1

Where, d1 = Inside diameter d2 = Outside diameter d = Mean diameter h = Mean height h1 = Total height ________

Flat blank diameter: D = √ d2 + 4dh

D2 – d2 Formula for calculating the cup height: “h” = --------------

4d

Some of the factors are listed below. 1. Blank diameter 2. Percent reduction in drawing and re-drawing 3. Draw force 4. Blank holding force 5. Ironing force 6. Hydraulic press of proper capacity 7. Whether Draw beads are required or not

1. BLANK DIAMETER It is the diameter of the flat blank produced from blanking tools. This must be determined theoretical calculations. 2. PERCENT REDUCTION IN DRAWING AND RE-DRAWING

It is also known as reduction ratio. This should also be determined for successive reduction to produce a final component. i) Percentage Reduction (P) = 100 (1 –d/D) Where, d = Internal diameter of the cup

D = Outer Diameter of the Cup

t0 X t ii) Reduction ratio (%): Ri = --------------- X 100

t0

Where, t0 = Thickness of cup wall before Ironing

t = Thickness of cup wall after Ironing iii) Possible number of reductions for a given ratio of shell height with respect to the diameter

Ratio H/d No. of draws

I draw %

II draw %

III draw %

IV draw %

Upto 0.8 1 40 - - -

0.8 - 1.5 2 40 25 - - 1.5 - 3.0 3 40 25 15 10

3.0 - 4.5 4 40 25 15 10

3. DRAW CLEARANCE

It is the intentional gap provided between draw punch and die for successful

draw operation. Depending upon the type of metal and operation generally this allowance range from 7% - 20% of material thickness.

4. DRAW FORCE or CUPPING FORCE This force is a function of the strain factor and other variables required to select

appropriate capacity press. Usually, Hydraulic presses are preferred for draw operations.

Cupping force (Fc) = Aw x Sy x nc x In Ec Where, Fc = Cupping force

Aw = Cross sectional area of the cup (Aw = Π X dt) Sy = Yield strength of material nc = Deformation efficiency of cupping In Ec = Natural logarithm of strain factor Ec Deformation efficiency (nc) is a factor varies from 0.6 – 0.7

DRAW FORCE or CUPPING FORCE (FD): [SU + SY]

FD = ∏ X d X t X ------------ X h = ----- Kg 2

Where, d = Punch diameter h = Height of the cup t = Stock thickness

Blank holding pressure: Fb = 0.3 X FD Total Draw force: FN = 1.3 X FD

LUBRICANTS Lubricants are used to reduce friction between surfaces and assist material flow during the draw operation. While selecting the lubricant for a particular type of draw, consider the following points carefully. POINTS TO BE CONSIDERED WHILE SELECTING AN APPROPRIATE LUBRICANT

1. Depth of draw 2. Contour or profile of the component 3. Mode of transport used 4. Material flow 5. Material specification (thickness, ductility, cupping property, treatments

required before and after the draw operation 6. Type of material: ferrous or non-ferrous 7. Drawing speed (speed of the ram head) 8. Pressure exerted on the blank holder plate 9. Function or application of the component (in its final shape) 10. Approximate time of producing the component and its dispatch time 11. Packing methods and mode of transport used

LUBRICANT’S PROPERTIES

The lubricant film must cover both surfaces in the areas required throughout the operation. A lubricant in addition to preventing metal to metal contact will also reduce friction and generation of heat.

LUBRICATION DURING DRAW OPERATION A good lubricant when applied on punch and die, stops direct contact of the component with the punch and die. Any lubricant that breaks down after a short period of use is obviously useless for drawing sheet material. The load applied by the punch and die is transferred to the component material without directly contacting but via through the lubricant. Because of the elongation of the lubricant medium a shining surface occurs on all the drawn components. Due to friction too much of heat is generated. To dissipate this hot water soluble lubricant has to be used. TYPES OF LUBRICANTS AND THEIR APPLICATION 1. Lubricating oil

This is suitable only for drawing small cylindrical cups and not advisable for larger and thicker components. This evaporates easily and also creates local non-lubricated zones.

2. Graphite powder Even though graphite is self lubricating, not much used in practice and may be

useful for small diameter drawn components.

3. Zinc oxide This is a very fine powder white in color widely used for all general draw

operations. Zinc oxide is available easily in the market with reasonable price compared to other lubricants. 4. Molybdenum Sulphide powder

This is a black powder and best lubricant medium used for draw operations.

When compared with zinc oxide this is superior but very expensive. This is best suited for sheet material of thickness 2 mm and above.

5. Lubricant solution (Mixture) For Steel: 3% colloidal compound with 67% water For Brass and Copper: 5% soap flakes, 28%, colloidal compound with 67%

water For Tin: Lubrication not required since this material is self- lubricating

Most common methods of applying lubricant

1. Using a Brush 2. Swabbing 3. Using Roller-coating

4. Dipping the blank or stock in a lubricant bath 5. Spraying on the area where maximum draw force is concentrated

DEFECTS IN DEEP DRAW OPERATION

1. Burr collection at the draw die 2. Thinning 3. Cracking 4. Score marks 5. Ejection problems 6. Puckering 7. Wrinkling 8. Earring 9. Material and its influence 10. Surface finish 11. Wrong tool setting 12. Operator’s negligence REASONS AND REMEDIES FOR DEFECTS IN DEEP DRAWING OPERATION 1. BURR COLLECTION AT THE DRAW DIE Fine powder like particles gets collected at the bottom of the die due continuous use. Causes:

1. Type of sheet material used for producing the component 2. Thickness of the sheet material used

Remedies:

1. Polish the draw die and draw punch and smoothen the flow radius and inside surface and use good lubricant such as ‘Molybdenum sulphide’

2. THINNING It is a frequent problem which occurs during draw operation. Due to this thickness of the component steeply reduce and give rise to its height.

Causes:

1. Clearance is insufficient 2. Lubrication problem 3. Insufficient die radius or punch radius 4. Drawing speed is more

Remedies:

1. Appropriate clearance is to be given in each draw stage 2. Use good lubricants such as molybdenum sulphide, so that the material

flows evenly during draw operation

3. CRACKING Splitting of wall surface of a finished component is known as “Cracking”. It invariably occurs after thinning

Causes:

1. Draw clearance is insufficient 2. Lubrication problem 3. Insufficient die radius or punch radius 4. Drawing speed is more

Remedies:

1. Appropriate clearance is to be given in each draws 2. Use good lubricants such as ‘Molybdenum sulphide’, so that the material

flows evenly during draw operation 3. Check the draw radii of both punch and die. Maintain them properly

throughout the profile. If it is less increase them (i) For die = 4t to 10t (ii) For punch = 3t to 5t

4. SCORE MARKS These are marks formed on the component or on punch and die due to fouling of parts or particles of the sheet material.

Causes:

1. Lubricant used is not effective. 2. Fouling is caused by the building up of particles of the sheet material from

the drawn cup on both the punch and the die which leads to scoring of the surface of the end product.

Remedies:

1. Dismantle the tool. Clean the punch and die surfaces, lubricate and reset them.

2. Polish the draw punch and draw die. 5. EJECTION PROBLEM The component is struck either to the draw punch or with the draw die and is not getting ejected for consistent production. Causes:

1. Insufficient draft on punch or die 2. Lubrication problem

Remedies: 1. Check the draft on draw punch and draw die radii 2. Rectify by providing positive draft on die 3. Provide good lubricant such as “molybdenum suplhide”

6. PUCKERING This is a defect mostly found in shallow drawing and less frequent in deep

drawing. This is similar to wrinkling but takes place inside the die, after the metal has begun to form inside the die aperture.

Causes:

1. Poor die design and providing too much draw clearance 2. Stresses in the material are the underlying cause of this phenomenon 3. Lack of ductility (sheet material may be hard and not accepting the

operation) Remedies:

1. It is difficult to set right the die 2. Redesign the tool 3. Trial to be made with draw quality stock material

7. WRINKLING

It is defined as the deformation of material into ups and downs on the surface. This defect takes place between the pressure plate (blank holding plate) and the die face. Causes:

1. Insufficient pressure on the pressure pad that holds the blank

2. Increase in the stress or stress concentration in the stock material of the component

Remedies: 1. Apply appropriate pressure on the pressure pad 2. Use of draw beads on the die

8. EARRING

These are the extra projections caused by the directional properties in the sheet material from which the cups are drawn.

Causes:

1. Cold working tends to produce preferred orientations in sheet materials 2. When rectangular blank is drawn to a rectangular shallow bowl

Remedies: 1. Earring can be minimized by avoiding excessive deformation in the deep

drawing process 2. Shape and size of the ears can be controlled to some extent by varying

the shapes of the blank (oval or even squared instead of circular).

9. MATERIAL AND ITS INFLUENCE The type or quality of stock material is a very important factor controlling the

technique employed to produce any given article.

Causes: 1. When tool is used for other materials to manufacture same components. 2. Inferior quality of material supplied in the subsequent batch of material

supply Remedies:

1. A good quality of material is essential 2. Different tools to be used for each type of material.

10. SURFACE FINISH

Surface quality of the deep drawn component depends largely on the grain size of material of the sheet material, from which it is blanked and drawn. Causes:

1. Coarse grains do not come into contact with the die face 2. The surface often resembles as orange peel (flakes). Hence, it is also

called as “ORANGE PEEL EFFECT”

Remedies: 1. Adequate control of grain size in the sheet to be drawn, is necessary 2. Final annealing process must be standardized and carried out for every

subsequent draw operations and annealing at too high temperature or for too long period leads to formation of coarse grains

3. In case of mild steel normalizing the drawn cup at 910ºC, instead of annealing at 650ºC, leads to re-crystallization of material with fine grain size

11. WRONG TOOL SETTING Some times the tool setter does not have the knowledge of proper procedure of loading the tool, which may lead to serious tool damage. Cause:

1. The tool setter sets the tool wrongly without following the procedure 2. He may be over confident or ignorant or not knowing the procedure 3. He may try to use the available facility

Remedies: 1. Having obtained all the relevant information and procedure of tool setting,

the tool is to be set properly by the tool setter 2. Few of the things include proper clamping of the tool, lubrication, setting of

proper shut height, screws on pressure plate to be checked twice, tightening of punch and die etc

12. OPERATOR’S NEGLIGENCE In many instances the operators are inexperienced or experienced by just

assisting the senior operators and proclaiming themselves as skilled operators. Because of this the basic problem, the industry faces high risk on valuable tools

and equipments. Causes:

1. Conversation with another operator 2. Disobeying the instructions 3. Lack of knowledge in the draw tool operation

Result: 1. Sometimes complete destruction of the tool 2. Production will be held up for many days till the tool is rebuilt 3. Product become scrap

Remedies: 1. Operator must be cautious about the work 2. Operator has to obey the instructions 3. Safety instructions have to be strictly followed 4. The supervisor must be vigilant and has to supervise all of these functions

HIGH END PRESS TOOLS

HYBRID OPERATION

1. LOVRING:

Louver is a partial tearing and bending operation usually made on engine covers, cabinets, etc for the entry of air. This unique operation is commonly done for air vents for stabilizer cases, regulator cases, electrical panels etc., where air has to circulate and keeping the equipment cool. It is a passage with flat sloping profiles with one side opening to allow light and air to enter in while keeping rain water out. In this operation only one side is cut and the other three sides are bent, such that, the air can enter into the equipment through the opening.

Entry for air

2. LANCING:

Lancing is a very important press operation involving 3 or 2 side shearing and one side bending or forming. This operation is widely used to provide relief for the matching part. It is also used to locate one part into the other.

In many of the sheet metal application lancing is used to lock the part to the other for proper assembly. Ex: Mosquito coil stand. This is also a partial tearing and bending operation. Usually two or three sides are teared with one side left with the parent material. Used for spring locking in the assembly or riveting. This is a combined bending and cutting operation along a line in the work material. The punch is designed to cut on two or three sides and bend along the fourth side.

LANCING

TYPES OF PRESS TOOLS

TYPES OF

PRESS

TOOLS

SINGLE STAGE TOOL

MULTI STAGE TOOL

COMPOUND TOOL

COMINATION TOOL

FINE BLANKING TOOL

COMPOUND TOOL

Already we have dealt with Single stage & Multi stage press tools in the previous chapters.

We shall try to understand other special press tools in brief.

COMPOUND TOOL INTRODUCTION In progressive tools burr produced by blanking & Piercing appears on both the surfaces of the sheet material, which is most common. But, whenever we require a component with high degree of dimensional accuracy, flatness, free from cumulative errors and burr of piecing & blanking on one surface of the sheet material, then best option is to manufacture a special tool called “COMPOUND TOOL”. PRINCIPLE The basic principle of this tool is both Piercing and Blanking operations will be performed in the same working cycle or stroke of the press.

same surface onlyand Blanking appears on the The cut band for both Piercing

Fracture

Piercing

Blanking

Strip layout of Compound tool

COMPONENT

STRIP W

IDTH

PITCH

COMPARISON BETWEEN COMPONENTS PRODUCED FROM PROGRESSIVE TOOL & COMPOUND TOOL

PROGRESSIVE COMPONENT

CUT BAND

FRACTUREBLANKING

BLANKING

PIERCING CUT BAND

PIERCING

FRACTURE

COMPOUND COMPONENT

PIERCING

CUT BAND

FRACTURE

PIERCING

BLANKINGFRACTURE

CUT BANDBLANKING

1. Burr appears on both the surfaces of the sheet material.

2. Perfect flatness is not achieved.

3. Cumulative error is common because of progression.

4. Produced components are used for semi precision assemblies.

1. Burr appears on the same surface of the sheet material.

2. Perfect flatness is achieved.

3. Elimination of cumulative error because, there is no progression.

4. Components are used for high precision assemblies since they posses high dimensional accuracy.

CONSTRUCTION Compound tool is a complete cutting press tool. Usually in progressive tools, all the punches are fixed to the top unit and the die will be to the bottom unit. But in compound tools, the blanking die is fixed to the top and the blanking punch which has piercing die will be mounted on the bottom plate. The piercing punch is fixed to the top unit with punch holder, supported by punch back plate and top plate. Shedder: These are normally spring loaded and will have sliding fit with the piercing punch and the blanking die. Shedder guides the piercing punch during the operation and helps in ejecting the component after the operation. A spring loaded stripper is provided in the bottom unit moves up and down around the blanking punch, has strip guide pins instead of guide plates. Since, the cutting pressure is concentrated in the middle of the die set centre pillar die sets are most appropriate.

Component

Blanking punch

Piercing punch

Shedder back plate

Shedder

CLASSIFICATION: 1. SIMULTANEOUS ACTION (CUT & CARRY SYSTEM) 2. DELAYED ACTION (KNOCK-OUT SYSTEM) 1. SIMULTANEOUS ACTION (CUT & CARRY SYSTEM) In this method the component is separated during the piercing and blanking operation, ejected from the die and get fixed into the blanking opening in the skeleton strip, carried along with it. This method is called as CUT & CARRY. FUNCTIONING When the top unit exerts pressure on the strip the actual cutting operation takes place simultaneously. After the operation, the top unit starts moving upwards, the blank which has entered the blanking die will be ejected out with the help of spring loaded shedder. Simultaneously, the strip is also removed from the blanking punch by the spring loaded stripper. Because of this action, the component enters into the stock material opening and gets embedded. There by perfect flatness is once again achieved and the cycle continues.

Compound tool with SIMULTANEOUS ACTION

(Cut & Carry system)

ADVANTAGES & DISADVANTAGES OF SIMULTANEOUS ACTION (CUT & CARRY SYSTEM)

Sl. N0.

ADVANTAGE DISADVANTAGE

1 This is a mechanical system of ejecting the component from the die.

Top unit construction is complicated compared to delayed action ejection system. Shank should have a bore for inserting a helical spring.

2 Component will be carried along with the strip. Hence, flatness of the component.

There are chances of component getting stuck in the die opening due to insufficient spring force.

3

a) Thin and large components are forcibly inserted in the skeleton strip and do not stick to the shedder face. b) Damages to the die due to this can be easily prevented. c) Does not require manual removal of the component.

This method has its own limitation. Thick components (more than 2 mm) require only delayed ejection system.

2. DELAYED ACTION (KNOCKOUT SYSTEM) This delayed action in a compound tool is obtained by “Knockout system”. This system is comprised of

1. Shedder 2. Knockout pin 3. Knockout plate 4. Knockout rod 5. Drop bar

FUNCTIONING When the operation is completed, the component will get stuck in the blanking die. During the return stroke, shedder is lifted, knockout pins which are provided beneath the shedder also gets lifted up and lifting the knockout plate. This knockout plate which is just placed on the knockout pins lifts the knockout rod. This rod is inserted through the shank hole. Drop bar which is an accessory of the machine also gets lifted up.

In the press, there are adjustment screws provided on either side of the ram head which will push the drop bar. This push force is sufficient to kick the knockout rod. Thus knockout plate will push the knockout pins, which drives the shedder down resulting in the ejection of the component from the blanking die.

The component will fall on the stripper of the bottom unit which is to be removed either by blowing the air or collected manually.

Compound tool with DELAYED ACTION

(KNOCKOUT SYSTEM)

ADVANTAGES & DISADVANTAGES OF DELAYED ACTION

Sl.N0. ADVANTAGE DISADVANTAGE

1 This is a mechanical system of ejecting the component, positively from the die.

Top unit construction is complicated.

Shank should have a hole for inserting the knock out rod.

Press should have the knock out facility.

2 There are no chances of component getting stuck in the die.

Component is not carried along with the strip.

Flatness of the component may not be achieved.

3 Damages to the die due to this can be easily prevented.

a) Thin sheet metal components may stick to the shedder face and does not fall on its own weight.

Every stroke requires manual removal of component which hampers the production.

b) This method has its own limitation.

Larger component requires only spring loaded ejection system.

The following are some of the general advantages & disadvantages of Compound tools over Progressive tools or Single stage tools.

Sl. No.

ADVANTAGE DISADVANTAGE

1 High degree of accuracy can be achieved.

Die design & manufacturing is complicated due to many operations being carried out in a single station.

2 Cut band and Burr of piercing & blanking appears on the same surface

Being complicated, the skill involved in the manufacture of the compound die is higher and tool manufacturing time is also considerably more.

3

Since all the operations are performed in one station, components will have close dimensional accuracy. This easily eliminates any inaccuracy that can originate due to piloting in progressive dies and locating in single stage tools.

Having too many operations carried out in a single station, the tools are not rigid and strong. This fact makes such tools to frequent breakdown and tool maintenance and repair requires higher skill.

4

These dies maintain the repeated accuracy, It is possible to produce a component with perfect flatness.

It is difficult to design compound dies for thick components as the strength of die section will not be that strong compared to a progressive die.

5

Compound dies are used to produce component from very thin material which are too delicate for pitching and piloting.

Thin sheets are difficult to feed as it may buckle while feeding and results in dimensional variation.

FINE BLANKING TOOL

PRINCIPLE Fine blanking is one of the methods of producing components without Fracture or Die break. This is done by controlling metal flow into the die. An inverted “V” projected ring called “IMPINGER”, which has a knife edge is pressed into the sheet metal outside the cutting line and the metal outside this line is restrained by the application of great force called “Strip holding force”.

1) This impinge ring will not allow the material to flow into the die.

2) The clearance between the punch and die will be around 0.007mm (7 microns) irrespective of material thickness and type of material.

As a result of these two (close clearance or insufficient clearance and restriction to metal flow) a clean, smooth cut edge is produced.

COMPARISON BETWEEN CONVENTIONAL BLANKING WITH FINE BLANKING

CONVENTIONAL BLANKING: As the sheet metal is not held properly, it tends to lift, when the punch starts applying the load. Thereby defect known as “dishing” occurs in the piece part.

LOAD

Dishing

Lifting of stock

RadiusDie

FINE BLANKING: Both Blanking and Piercing operation is performed simultaneously by the applied shear force. Rollover radius is eliminated by firm holding of the stock, with the help of “IMPINGER”.

Blanking punch

Impinger

Die

Piercing punch

Shedder

Slug ejector

Component

DESIGNATION OF IMPINGER PROFILE IN FINE BLANKING TOOL

A

h

r

90.0°

0.05 to 0.1

Stripper

1

2

3

4

5

6

MaterialThickness A h r

1-1.7 1 0.3 0.2

1.8-2.2 1.4 0.4 0.2

2.3-2.7 1.7 0.5 0.2

2.8-3.2 2.1 0.6 0.2

3.3-3.7 2.5 0.7 0.2

3.8-4.5 2.8 0.8 0.2

For Stripper plate

Since intentionally insufficient cutting clearance is provided between the punch and die, the width of the cut band is automatically extended to the full thickness of the stock material. As tensional burr appears during separation of the component, secondary operation like de-burring using vibrators, tumblers, etc are employed to remove this burr only. Generally, fine blanked component does not require any secondary press operation like shaving, trimming etc.

CONSTRUCTION OF THE TOOL The construction of the tool almost resembles a compound tool. The only difference is the addition of V - inverted impinge ring around the blanking area. This impinge ring is provided usually on the floating stripper, which projects from the stripper top surface. Impinger ring is made from tool steel OHNS (T110 W2 Cr1), hardened and well polished with sharp knife edge. The tool should be rigid enough to absorb the heavy load. Hence, the die should be thick enough and housed in a hardened OHNS material and this again housed in a main housing made of St-42 material. Generally, for fine blanking tools four pillar die sets with ball cage are preferred for higher rigidity and frictionless movement. Fine blanking tools requires sophisticated machines to manufacture and skilled workmen to assemble and maintain.

Sectional elevation of fine blanking tool

IMPORTANT STAGES IN FINE BLANKING Fine blanking operation involves four main stages.

1st stage: Impingement 2nd stage: Cutting operation

3rd stage: Ejection of the component 4th stage: Positioning fresh portion of the stock strip

Initial stage: Die is in open condition. Stock material is placed in between punch and die.

1st stage: Impingement: Tool is in closed condition. Stock material is held firmly between the IMPINGER which is fixed on the DIE and the spring loaded STRIPPER

2nd stage: Cutting operation: Blanking and Piercing operations are accomplishing simultaneously by the applied shear force. Rollover radius is eliminated by firm holding.

Intermediate stage 1: Operation is completed. Blank is held firmly between the Blanking punch and Shedder. The pierced slug is held between the piercing punch and the ejector.

Intermediate stage 2: Top and Bottom units are separated, but the component and the slug are still within the tool. Skeleton stock is not released from the IMPINGER.

3rd stage: Ejection of the Piercing slug: Piercing slug is ejected by the ejector. Stock material is relieved from impinging pressure.

Intermediate stage: Ejection of the component: Component is ejected out by the Shedder and the skeleton strip is released from the inverted V- shaped IMPINGER

Intermediate stage: Stock strip movement: Component is ejected from the die. Stock material starts moving in the feeding direction.

4th stage: Positioning fresh portion of the stock strip: Component and the Piercing slug are removed by blowing high pressured air. Fresh portion of the stock material is again positioned for the next cycle.

FUNCTION OF THE TOOL Tool should be loaded on a Triple action hydraulic press. The three actions of the press are IMPINGEMENT or STRIP HOLDING, CUTTING and EJECTION. Bottoms ram moves upward to grip the stock with great pressure and impinge the stock material. Further, the bottom ram continues to move a distance equal to the stock thickness. And thus the blanking and piercing operations are accomplished. The lower ram descends and the shedder removes the component from the die whereas the pierced slug is removed by the ejector. Both component and pierced slug are collected in a container by blowing high pressured air. The stock strip is positioned for the next cycle in such a way that impinged area does not come in the new blanking area. Since impinged area cannot be used for producing the component, utilization of the stock material will suffer.

Sl. No.

ADVANTAGE DISADVANTAGE

1 Components posses smooth edge all over, perfect flatness, high accuracy and good finish.

Due to insufficient cutting clearance, die construction is complicated

2 Components do not require secondary operations which saves manufacturing time.

Shear force required is approximately 3 times more, compare to conventional shearing.

3

Tool cost approximately 50% more than the conventional tools, but the cost is more than offset by the elimination of secondary operation.

1. Higher tool cost. 2. Tool manufacturing and

maintenance requires a highly knowledgeable tool maker.

5

Components are used usually in automobiles, where matching of the assembled product is very precise. Ex: Sprockets, Gears, Free wheels, Chains etc.

Though the quality of component is unmatched with the component produced form conventional tools, not advisable for all types of components due to high production cost.

COMBINATION TOOL

PRINCIPLE Combination tools are unique press tool which perform both cutting and non cutting operations (usually draw operation) in one cycle of the press with better dimensional accuracy and quality. Generally, a Double action press with die cushion is quite essential for Compound tool, Draw tool and these Combination tools. CONSTRUCTION Combination tools are almost similar to a compound tool by appearance, but non-cutting die and punch are enclosed within the cutting area. Shedder which is a sliding fit in the blanking die acts as draw die also. An ejector is provided within the shedder to eject the component as soon as the top unit moves upwards completely. Normally, knock-out system is employed to do this ejection function. Either centre pillar or four pillar die sets are used in the tool construction for longer life of the tool. TOOL FUNCTIONING When the top unit start dwelling down, the stock strip which is placed on the floating stripper (spring loaded stripper) is held firmly before performing the operation. Further dwelling results in the blanking of outer contour of the flat blank. As the downward stroke continues, the cut blank starts entering into the draw die by the action of the draw punch, which is mounted on the bottom unit. Spring loaded shedder moves upwards and butts to the shedder back plate; thereby bottoming of the component is achieved.

As the top unit moves upward, the shedder starts sliding down by the spring action. The ejector which is within the shedder will knock the component out by the action of the knock-out system. Thus, the component will fall on the bottom unit (floating stripper), which may be collected either by blowing the air or collected manually. And the cycle continues in the same manner.

Sectional elevation of COMBINATION tool

COMPONENT

STRIP LAY-OUT

BLANKING & DRAWING

COMPONENT

STRIP W

IDTH

Sheet thickness

FEED PITCH

LIMITATIONS As this is a complicated tool the parts which involved in the direct production of the components are delicate. Hence, these tools are not advisable for:

a) Higher sheet thicknesses b) Holes and profiles which are too close to each other c) Drawn components having projections on the side walls

COMBINATION TOOL

ADVANTAGE

1. In one cycle of the press complete component is produced

2. Production time is less 3. Material handling is minimized 4. Requires no secondary

operations 5. Production cost is low compare to

other types of tools 6. Quality and dimensional accuracy

of the component is very high compare to conventional tools

DISADVANTAGE

1. Tool design is complicated 2. Requires sophisticated

machines to machine the parts 3. Assembly of the tool requires

highly skilled person 4. Tool cannot be loaded on

ordinary press 5. Accident to the tool is very

serious 6. Tool maintenance is expensive

7. Tool manufacturing cost is high

STRIP LAY-OUT There are two important methods of rolling in practice

HOT ROLLING Hot rolling is the core production process between melting and finishing operations. It is the main transformation stage where the billets are processed into bars wires, sheets or foils. If the sheets are rolled in hot condition, it is called as hot rolled sheets. COLD ROLLING Hot billets are cooled, cleaned, surface ground and Cold rolled to specific thickness on latest computer controlled mills, which continuously monitor the material for uniform gauge. TYPES OF SHEETS AVAILABLE

Sl. No. Type of Sheet Metal Available size

1

CRCA (Cold Rolled Close Annealed)

HR (Hot Rolled)

Aluminum 4’ X 8’

2

Brass

Copper

Phosphor bronze

12’’ X 48’’,

14’’ X 48’’ & Coil form

UTILIZATION OF STRIP During the production of stampings, major consideration is very often given to the economical use of the raw material and blank lay-out in general is planned with minimum scrap. UTILIZATION FACTOR It is the percentage of the raw material (stock material) used in the component. Represented by:

Methods of Rolling

Hot Rolling

These sheets are generally referred as

“HR”

Cold Rolling

These sheets are generally referred as

“CR”

Where,

fo = (Surface area) Area of the material in the component f1= (Surface area) Area of material required to produce the component K W = Utilization factor 100 = To convert the value into percentage

Ex: Blank size = 20mm x 30mm and the value of Scrap bridge and Side scrap =

1.75mm Pitch = 21.75mm and Strip width = 33.5mm fo K W = ---------- x 100 f1

fo = 20 X 30 = 600 mm2

f1 = 21.75 X 33.50 = 7728.62 mm2 K W = (600 / 728.62) X 100 K W = 82.34%

1000 No. of components per meter = ----------

Pitch 1000 No. of components per meter = --------------- = 45.97

21.75

No. of complete components = 45

METHOD OF CALCULATING NUMBER OF COMPONENTS PER SHEET WITHOUT ANY SCRAP

Ex: Component dimension = 15mm x 45mm Sheet dimension = 4’ x 8’ (4 Feet x 8 Feet)

[Standard size of CRCA steel sheet] 1st step: Convert Feet to Millimeters [mm]

We know that, 1feet (1’) = 12 Inches (12”) 1 Inch (1”) = 25.4mm

4 Feet = 1219mm and 8 Feet = 2438mm

(Decimal values are neglected) 2nd Step: In a sheet of 1219mm x 2438mm

2438

fo

K. W = ------- x 100 =------%

f1

Number of pieces produced of size 45mm = ----------- = 54 45

1219

Number of pieces produced of size 15mm = ------------ = 81 15

3rd Step: Number of pieces from the sheet (1219mm x 2438mm)

= 54 x 81 = 4374

[Conclusion: From a sheet of 4 Feet x 8 Feet, number of pieces produced are 4374] Important note: Practice the above calculation for other sheet sizes with different blank

dimensions. As per thumb rule the Scrap bridge and Side scrap is as follows:

1.5 X sheet thickness for metallic materials 2.0 X sheet thickness for non-metallic materials

BLANK LAY-OUT The initial preparation of tool design, involves deciding the position of cutting tool, stopping positions, direction of feed and its value, instruction of feeding the strip and operations in the tool. DEFINITION It is a plan of cutting the blanks from the stock with optimum economy which is influenced by many factors. Sometimes when there is no provision for deciding precise and economical strip lay-out for irregular contours, blank lay-outs are more preferred. STRIP LAY-OUT Strip lay-out is very important as it serves as the basis for designing and manufacturing of press tool. DEFINITION It is a complete plan of producing the component in a progressive tool from the stock material. Nomenclature such as sequence of operation, the location of tool limit at each station, operation taking place at each station, feeding direction etc, are clearly indicated.

There are different methods of blanking out the desired shape. Before the tools are designed, it must be decided which method is to be adopted.

The following important points are to be considered while designing a strip lay out.

Sl. No. Strip lay out points

1 Stock material from which blanks are cut

2 Direction of burr on the component

3 Grain direction in the stock material

4 Direction of feeding the stock strip

5 Production quantity of components required

6 Tool cost

7 Specification of press

8 Tool making possibilities and facilities

9 Scrap and Utilization factor of stock material

BlankingPiercing

End Stopper

Strip width

Side Scrap

Side Scrap

Scrap Bridge

Pitch

WORKED OUT EXAMPLE FOR DESIGNING SEQUENCE OF PRESS TOOLS FOR

THE DRAWN COMPONENT

The below drawn cup requires four different types of tools to produce. It is always

better to understand the component well, before designing the tool.

Different stages of press operations for drawn cup

1. Blanking tool: To produce Flat blank required for drawn cup

2. Draw tool: To shape flat blank into a cup

3. Piercing tool: To originate a hole in the centre of the drawn cup

4. Cantilever Piercing tool: To originate a hole at the side of the drawn cup

3-D VIEWS OF THE DRAWN COMPONENT

1. BLANKING TOOL

Sectional elevation of the blanking tool

This is a single stage cutting operation tool which performs only one operation

like Blanking. Centre pillar die set is used assuming huge volume of components and

concentration of shearing load in the middle.

Die set is always optional depending on the

1. Stock thickness 2. Type of sheet material 3. Clearance between punch and die 4. Type of press used 5. Quantity required 6. Speed at which the tool has to work

Fixed stripper or box stripper (Channel stripper) used as the sheet thickness is

quite thick. For easy falling and collection of blanks spacers are provided under the die set.

2. DRAW TOOL

Sectional elevation of the draw tool

Flat blank is shaped into a circular cup with flange. The alignment between

punch and die is made perfect to avoid draw defects like Tearing, Earing and Elongation.

Blank locator is provided on the die for placing the flat blank in the perfect

position. Spring loaded pressure pad is provided for two reasons.

a. During draw operation, the flat blank is firmly held between punch and pressure pad, resulting in uniform flow of material in to the die.

b. During the return stroke of the top unit the drawn cup is also ejected or

removed from the die simultaneously. This will avoid distortion of drawn cup shape.

Centre pillar die set is provided, as the draw pressure is centrally located. Setting spacers: These are used for several reasons.

a. Tool setting on the press is very easy

b. To control the downward stroke of the top unit

c. To avoid accidents to the tool, during the component production

d. Any slight change in press setting during production will not affect the quality of the component.

3. PIERCING TOOL

Sectional elevation of centre piercing tool

Whenever a hole is required in a drawn component, it is always better to pierce,

after the draw operation. If the hole piercing is done before the draw operation, during the draw operation

the material undergoes severe strain and resulting in stretching irregularly. Due to this, the pierced hole loses its dimension, position and desired shape. As the component requires a hole in the bottom, above tool is designed. The stripper is spring loaded and will have the same profile projection as that of

the inside profile of the component for better holding and location. A locator is fixed on the die has outside profile of the component for easy loading

of the component during production. Solid yoked die with collar is used, as there is only one hole to be pierced. These

dies will save the tool cost at many times.

Centre pillar die set is preferred as the piercing load is located in the centre of the dieset.

A hardened die back plate is used to absorb the downward thrust, exerted by the

punch during the cutting operation. Similarly, a punch back plate is also provided above the punch to avoid

penetration of piercing punch head in the top plate during the cutting operation.

Setting spacers: These are used for several reasons. 1. Tool setting on the press is very easy

2. To control the piercing punch depth in the die during the operation

3. To avoid accidents to the tool during the component production

4. Any slight change in press setting during production will not affect the

quality of the component

4. CANTILEVER or SIDE PIERCING TOOL

Front elevation of side piercing tool

This is an example for Cantilever piercing or Side piercing, which is done after

the draw operation. The reason is the piercing cannot be done before the draw operation as the hole loses its orientation and shape during drawing.

Example: For fixing the handles to the pressure cooker bowl and lid, this type of operation is easy and preferred.

In this tool,

A component locator is inserted in the holder. This holder is fixed on the base plate with screws and dowels.

A spring loaded holder is provided to hold the drawn cup during the operation. Rear pillar (Back pillar) die set is chosen for the following reasons.

1. Easy loading and unloading of the component 2. Clear visibility of the operation 3. Operator’s friendly

ESTIMATION AND COSTING OF PRESS TOOL

It is an art of finding the cost of the product before manufacturing. It is defined as the probable cost of the product by assuming the cost and expenses, which are probably incurring in different sections and processes.

Estimation requires highly skilled technical knowledge about manufacturing

method and operating time. ADVANTAGES

a. Estimation prevents the loss to the manufacturer by giving him the nearest price of the product, before manufacturing.

b. It aims at taking decisions to make or purchase.

c. It helps to arrive at the price setting where, there is no established data.

d. It will also help in comparing the actual production cost with the estimated price.

PRESENT MARKET RATE OF THE MATERIAL

Sl. No. MATERIAL RATE in Rs. per KG

1 M.S 80-00

2 17 Mn 1Cr 95 90-00

3 OHNS 180-00

4 HCHCr (D2) 380-00

5 HCHCr (D3) 280-00

PRESENT HEAT TREATMENT CHARGES

Sl. No. TYPE OF TREATMENT RATE in Rs. per KG

1 Case hardening 25-00

2 Hardening and tempering 33-00

GENERAL MACHINING CHARGES

Sl. No.

TYPE OF MACHINING RATE in Rs. Per HOUR from January

2008

1 All general purpose machines 170-00

2 CNC/Jig Boring/Wire Cut/

Jig Grinding/EDM 680-00

3 Bench work 140-00

4 Trials 300-00

5 Design 300-00

6 Inspection 220-00

7 Tryout 300-00

8 Batch production 800-00

9 Final production 600-00

DIRECT MATERIAL COST

Sl. No.

Name of the item Matl. Total

weight

Cost per

Kg in Rs.

Cost in

Rs.

1 Die block HCHCr 5 380/- 1900-00

2 Stripper M. S 5 60/- 300-00

3 Punch holder M. S 5 60/- 300-00

4 Top plate M. S 18 60/- 1000-00

5 Bottom plate M. S 22 60/- 1200-00

6 Guide plate OHNS 2 160/- 320-00

7 Punch back plate OHNS 3 160/- 480-00

8 Pillar & Bush OHNS 6 160/- 960-00

9 Strip guide support

plate M. S 1 60/- 60-00

10 Punch wire cut block HCHCr 5 380/- 1900-00

GRAND TOTAL 8,420-00

COST BREAK-UPS

Sl. No. COST PARTICULARS INCURRED COST in

Rs.

1

Prime cost (PC)

= Direct matl. cost + Direct Labor cost(Approx. 85% of Direct matl. cost)

= 8,420 + 7,000

15,420-00

2 Over heads expenses = 20% of (PC) 3,084-00

3 Cost of Standard items (LUMP SUM) 2,500-00

4 Total Machining cost (Includes Jig boring, Heat treatment and Wire cut)

28,000-00

5 Design charges = 20% of (PC) 3,084-00

6 Assembly charge =@Rs.140 X 120 hrs 16,800-00

7

Inspection charges

= No. of hrs X Rate (Rs. 220/-)

= 4 X 220/-

880-00

8

Try-out charges/Shift

= No. of hrs X Rate (Rs. 300/-)

= 8 X 300

2,400-00

9 Miscellaneous = (40% of (PC) 6,168-00

TOTAL COST 78,336-00

SELLING PRICE

Sl. No. Description of Cost Cost in Rs.

1 Total Cost 78,336-00

2 Profit (10% of Total Cost) 7,833-60

SELLING COST 86,169-60

Rs. EIGHTY-SIX THOUSAND ONE HUNDRED SIXTY-NINE & PAISA SIXTY ONLY

PRACTICE THE FOLLOWING ON YOUR OWN Exercise No: 1

1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

25 42

8

66

5360

88107

96

122

R2 (TYP)

R20

7

Ø6

Ø5

Ø10

R3

9915

2

93°

87°

93°

Component details:

1. Material: CRCA 2.0mm 2. Scrap value for scrap bridge and side scrap: 3.5mm 3. Shear strength: 38Kg/mm2

Exercise No: 2 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

Ø21

3

44

Ø4(2-Holes)

R20

R4 Component details:

1. Material: CRCA 3.0mm 2. Scrap value for scrap bridge and side scrap: 4.5mm 3. Shear strength: 33Kg/mm2

Exercise No: 3 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

50

8

20 25

43

5

10

10

10

815

33

40

90°

R6

Ø4(4-Holes)

R3(Typ)

2

Component details:

1. Material: Brass 2.0mm 2. Scrap value for scrap bridge and side scrap: 3.5mm 3. Shear strength: 22Kg/mm2

Exercise No: 4 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

1030

40

8

15

203040

8

24

12

R2(Typ)

Ø6(3-Holes)

15

3

Component details:

1. Material: Brass 3.0mm 2. Scrap value for scrap bridge and side scrap: 4.5mm 3. Shear strength: 28Kg/mm2

Exercise No: 5 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

5

15

40

12

2812

R3(Typ)

R15(Typ)

Component details: 1. Material: Aluminum alloy, 1.75mm 2. Scrap value for scrap bridge and side scrap: 3.5mm 3. Shear strength: 19Kg/mm2

Exercise No: 6 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

15

21

31

186

27

10Ø2(6-Holes) R2(Typ)

6

9

17

3945

Component details: 1. Material: Steel 0.5%C, 1.25mm 2. Scrap value for scrap bridge and side scrap: 2.0mm 3. Shear strength: 56Kg/mm2

Exercise No: 7 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

5 5

27 33

30

55 60

55

5

5

27

33

Ø4(2-Holes)

Ø20

R4(Typ)

R20(Typ)

30

Component details:

1. Material: Steel 0.3%C, 1.8mm 2. Scrap value for scrap bridge and side scrap: 2.75mm 3. Shear strength: 42Kg/mm2

Exercise No: 8 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

5

6

2646

56

36

28

51

62

46

3128

51 56

R5(Typ)

R5(Typ)

R3(Typ)

Ø2(4-Holes)

Ø5(3-Holes)

36

Component details:

1. Material: Phosphor bronze 1.5mm 2. Scrap value for scrap bridge and side scrap: 2.75mm 3. Shear strength: 52Kg/mm2

Exercise No: 9 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

38

20

19

38

2933

30R5(Typ)

R5(Typ)

R5

Ø3(7-Holes)

24

30

R10

Component details:

1. Material: Copper 0.5mm 2. Scrap value for scrap bridge and side scrap: 1.25mm 3. Shear strength: 28Kg/mm2

Exercise No: 10 1. Design an economical strip lay-out. 2. Calculate the Utilization factor. 3. Calculate number of components per strip length of 1200mm. 4. Calculate number of components per sheet of size: 4 Feet x 8 Feet 5. What is the sequence of press operations involved in this component? 6. Which type of Press tool, you recommend to produce this component? Justify

your answer. 7. Calculate the Cutting clearance per side using all the 3 methods. 8. Derive the dimensions of Punch & Die for both Piercing & Blanking. 9. Determine the required Shear force.

555

60

5

60

55

8 Ø42

Ø40

Ø4(4-Holes)

Ø4(4-Holes)

Ø15

4

9

6

45°

16

Ø25PCD

8SLOTS, EQUI-SPACED

26

4SLOTS, EQUI-SPACED

Component details:

1. Material: Silicon Steel 0.5mm 2. Scrap value for scrap bridge and side scrap: 1.25mm 3. Shear strength: 36Kg/mm2