Bahan Kuliah Manufacturing Procces I University Of Lampung

PROSES PRODUKSI I

Dr. Ir. Yanuar Burhanuddin, MT (Staf Pengajar Jurusan Teknik Mesin)

(Universitas Lampung)

Topik Kuliah• Pengantar Proses Manufaktur• Aspek-aspek manufaktur• Pengecoran• Pembentukan Logam Curah (Bulk)• Pembentukan Logam Plat (Sheet)• Pengelasan

BAB 1 PENGANTAR TEKNOLOGI PRODUKSI

PROSES PRODUKSI I

Produksi atau Manufaktur• Produksi: proses pengubahan bahan baku

menjadi produk/komponen.• Manufaktur: diturunkan dari kata Latin yaitu manu

factus yang berarti “dibuat dengan tangan”.• Teknologi produksi memberikan pengetahuan

dasar bahan teknik, penggunaan berbagai perkakas tangan dan mesin-mesin, penerapan berbagai metode produksi yang memfasilitasi pembentukan bahan mentah menjadi bentuk berguna yang diproduksi pada berbagai bengkel produksi.

Definisi Produksi atau Manufaktur• Produksi : 1. proses mengeluarkan hasil;

penghasilan; 2. hasil; 3. pembuatan (KBBI)• Manufaktur: diturunkan dari kata Latin yaitu manu

factus yang berarti “dibuat dengan tangan”.• Definisi:

Pengubahan bahan baku menjadi barang yang berguna dengan tenaga manusia atau mesin-mesin-mesin bertenaga (R. Timings).

• Manufaktur adalah serangkaian aktifitas mengubah bahan baku menjadi produk dengan cara hemat biaya yang paling mungkin. Aktifitas manufaktur termasuk merancang barang/produk, membuat komponen dan merakitnya menjadi produk (subassemblies) menggunakan berbagai metoda dan teknik, menjual produk ke pelanggan, memperbaiki, merawat produk dengan aturan kerja yang baik dan mendaur ulang bahan dan komponen (Springer Handbook of Mechanical Engineering)

TEKNOLOGI PRODUKSI• Teknologi produksi adalah mesin dan sarana

produksi yang membuat/ menciptakan produk fisik nyata yang layak bagi sebuah bisnis. Untuk sebuah usaha kecil, ini berarti setidaknya sebuah bengkel.

MODEL PROSES PRODUKSI

Bahan

PROSESProduk

Energi

Informasi

Mesin

Limbah

Manusia

Manajemen

PDB vs Produksi/Manufaktur

• Hubungan yang sangat dengan antara Produk Domestik Bruto (PDB) dengan produksi/manufaktur

• Kemajuan suatu negara ditopang kemajuan industri manufaktur

Manufaktur Global (Sumber: Timings)

Komponen dan bahan pada mesin mobil

Potongan dari mesin mobil yang menunjukkan berbagai komponen dan bahan yang digunakan. Sumber: Ford Motor Company. Ilustrasi oleh David Kimball.

Komponen pada ProdukProduk Jumlah KomponenSepeda 25Mobil 15.000

Pesawat Angkut Militer

> 4.000.000

Pesawat angkut penumpang Boeing

> 6.000.000

• Beberapa produk hanya mempunyai komponen tunggal (paku, baut, garpu, coat hanger, dll.)

• Beberapa produk adalah rakitan dari beberapa komponen (ball point, pena, mobil, mesin cuci, dll.)

• Semua komponen dibuat atau diproduksi.

•

Pembuatan Lampu Pijar

Komponen-komponen lampu pijar yang umum. Sumber: General Electric Company.

Tahapan-tahapan produksi dalam pembuatan lampu pijar. Sumber: General Electric Company.

Pemilihan Bahan-bahan untuk Klip Kertas

Berbagai contoh bahan dan geometri klip kertas

Pertanyaan:

• Apakah sifat-sifat bahan yang diperlukan?

• Karakteristik pembuatan apa yang diperlukan?

• Kalau jumlah yang akan diproduksi 1 juta/hari apakah strategi produksi sama dengan produksi 10 ribu/hari?

Sejarah ProduksiPeriode Bahan TeknologiSebelum 1 Masehi Emas, tembaga, besi,

perunggu, besi cor, baja cor, kayu

Penempaan, pengecoran, penarikan, penyeteman, potong menggunakan batu/tulang, keling, solder

1 – 1000 M Seng, Baja, Kuningan Bubut kayu, teknologi kaca

1000-1500 M Tungku tiup, penarikan kawat, etsa

1500-1600 M Aluminium Tempa menggunakan kincir air, pengerolan, teknologi kristal

1600-1700 M Pengecoran cetakan permanen, pengerolan

Aktifitas dan Hasil Produksi Manusia Dulu

Sejarah ProduksiPeriode Bahan Teknologi1700 – 1800 M Besi cor, besi krusibel Pengecoran, ekstrusi,

deepdrawing, bor, bubut ulir

1800 – 1900 M Nikel, babbit, baja wolfram, baja galvanis

Pengecoran sentrifugal, Bessemer, teknologi serbuk, frais, bubut copy, mesin gerinda, ekstrusi karet

1900 – 1940 M Plastik, komposit Cor cetakan, cor cetakan lilin, ekstrusi baja, pengelasan pendam, pengelasan busur listrik, pembuatan botol,

1940 - sekarang Plastik, komposit, magnesium, titanium

Proses Produksi• Pengecoran: cor cetakan habis, cor cetakan permanen• Pembentukan Logam Pejal: pengerolan, penempaan,

ekstrusi, penarikan• Pembentukan Logam Plat: pemotongan, penekukan,

penarikan• Pemrosesan Serbuk: pemadatan• Pemrosesan Plastik : injeksi, ekstrusi, kompresi• Pembuangan Logam: pemesinan, non-konvensional• Penyambungan: pengelasan, perekatan, pengelingan• Penyelesaian (Finishing): Pengecatan, Galvanis, Krom,

Sepuh

Jenis-jenis proses produksi

C en tri fugalD ie cas tingInvestm entP erm anen t m o ldS and cas ting

P eng eco ran(P eru bahan Fasa)

E x tru sionF org ingR ollingB ar d ra w ingW ire dra w ing

M as if/C u rah

B end ingB lank ingD raw ingP un ch ingS hear ingS p inn ing

P lat

P em be ntukan(D eform as i)

B low m old ingC as t ingC om press ion m o ld ingE x trus ionIn jection M old ingT herm ofo rm ingT ra nsfe r mo ld ing

P em rosesanP o ly m er

B oringD ri llingF ac ingG rind ingM illingP lan ingT urn ingS aw ingE C M , E D M

P em es ina n(P em buang an G eram)

A no diz ingH on ingP ain tingP la t ingP o l ish ing

P en ye lesa ia n A kh ir(P erm ukaan)

A u to m a tedB ond ingB ra z ingM anu alR ivet ingSo lde r ingW eld ing

P engg ab ung an/P enyam bungan

P rose s Prod uk si

How is the input material changed?

Proses Pengecoran

• Cetakan Pasir (Sand casting)• Cetakan Besi (Die casting)• Cetakan Keramik (Investment casting)• Permanent mold• Centrifugal Casting

Proses Pembekuan

Barang padat Bahan lebur pembekuan

Flow (voids, flash)Cooling time (cycle time)TemperatureMold complexity Warpage Post processing Costs (materials, tooling, processing)

Casting ProcessesSand CastingDie CastingInvestment CastingCentrifugal

Polymer ProcessesInjection MoldingBlow MoldingThermoFormingCompression Molding

Add to your notes

Proses Pembentukan Masif

• Pengerolan (Rolling)• Ekstrusi (Extrusion)• Penarikan (Drawing)• Tempa (Forging)

Rolling

slab

bloom

billet

sheet coil

bar rod

structural

ingot

Extrusion

RamCross

sections

Extrusion die

Billet

Penarikan (Drawing)

Pulling force

Crosssections

Drawing die

Billet

Tempa cetakan tertutup (Closed-die Forging)

Blockedpreform

Gutter

Ram pressure

Flash

Pembentukan Plat (Sheet metal forming)

• Bending• Blanking• Drawing• Punching• Shearing• Spinning

Sheet metal drawing

BlankDrawn part

Clamp force

Blank holder

Die

Punch

Punch ram

Polymer Processes

• Compression molding

• Transfer Molding• Blow molding• Injection molding

Compression molding

Charge

Heated mold

Part

Ram Pressure

Transfer molding

Charge

Ram

Heatedmold Sprue

Part

Ram pressure

Blow molding

Extruderair injector

parison

Part isremoved

Airblown into

parison

Mold halvesclose

Molten parison is extruded

Injection molding

Shear-heating

Cavity halfof mold

Core halfof mold

Ejector pins

Moving

Feed hopper

Sprue

Fixed

Barrel

Pellets

Mold closure direction

Parting plane/surfac

e

Machining processes

E x trus ionF org ingR o llingB ar d raw ingW ire d raw ing

D eform a t ion

C en tri fug alD ie ca s t ingInvestm entP erm a nen t m oldS an d ca st ing

C as ting

B end in gB la nk ingD raw ingP un ch in gS he ar ingS p inn ing

S hee tM e tal

B lo w m o ld ingC ast ingC om press io n m o ld ingE x trus ionIn jec tion M old ingT h erm oform ingT ra nsfe r m old ing

P o lym erP ro cesses

B oringD ri l lingF ac in gG rind ingM ill ingP lan ingT u rn ingS aw ingE C M , E D M

M a ch in ing

A n od iz ingH o ningP ain tingP la t ingP o l ish ing

F in ish ing

A u tom atedB o nd ingB raz ingM a nu alR ive t ingS o lde r ingW eld ing

A ssem bly

M a nu fac tu ringP ro cesses

Machining – removal of material…

Sawing –using a toothed blade.Milling – from a flat surface by a rotating cutter tool. Planing – using a translating cutter as workpiece feeds.Shaping - from a translating workpiece using a stationary cutter. Boring - increasing diameter of existing hole by rotating the workpiece.Drilling- using a rotating bit forming a cylindrical hole.Reaming – to refine the diameter of an existing hole.Turning - from a rotating workpiece. Facing - from turning workpiece using a radially fed tool. Grinding - from a surface using an abrasive spinning wheel.Electric discharge machining - by means of a spark.

Surface roughnessProcess Roughness ( inch)

Machining

Turning 32-250

Boring 16-250

Milling 32-250

Drilling 63-250

Reaming 16-125

Broaching 16-125

Finishing

Precision grinding 2-16

Lapping / honing 2-16

Super finishing 1-8

Machining process considerations

sawing, turning, boring, milling, drilling, grinding, ECM

material removed solid material machining

hardness, strength of materialshear forces = strong jigs & fixtures tool/bit wear, replacementsize of workpiece, fit machine?volume removedrate of removal, hp neededtolerances operator skill, CNCcosts (materials, tooling, processing)Add to your

notes

Aplikasi teknologi informasi untuk membuat cetakan kacamata anti-matahari

Pemesinan rongga cetakan pada pembuatan kacamata anti-

matahari

(a) Model komputer kacamata anti-matahari sebagaiman didesain dan dilihat pada layar monitor

(b) Pemesinan rongga cetakan menggunakan mesin frais yang dikendalikan komputer.

(c) Produk jadi/akhir. Sumber: Mastercam/CNC Software, Inc.

Video

Assembly processes – fastening / joining of 2 or more components

E xtrus ionF o rg ingR ol l ingB ar d raw ingW ire d raw ing

D eform ation

C en tri fug alD ie ca st ingIn vestm entP erm anen t m o ldS and cas t ing

C as ting

B en dingB lan k ingD raw ingPu nch ingSh ea ringSp inn ing

S hee tM etal

B low m old ingC ast ingC om press ion m old ingE x trus ionIn jec tion M o ld ingT h erm o form ingT ran sfe r m o ld ing

P o ly m erP rocesses

B oringD ri llingF ac in gG rind ingM ill ingP lan ingT u rn ingS aw ingE C M , E D M

M achin ing

A nod iz ingH oningP a in tingP la tingP o l ish ing

F in ish ing

A utom atedB o nd in gB raz ingM anu alR iv e tingS o lde ringW eld ing

A ssem bly

M anufac tu r ingP rocesses

permanent?

Pengelasan otomatik mobil

Pengelasan titik (spot welding) bodi mobil pada jalur perakitan mobil. Sumber: Ford Motor Company.

Video

Finishing processes

E xtrus ionFo rg ingR oll ingB ar d raw ingW ire d raw ing

D eform at ion

C e n tri fu galD ie ca s t ingInve stm entPe rm a ne n t m o ldSa nd cas ting

C a st ing

B end ingB lank ingD raw ingPu nch in gSh ear ingSp in n ing

Sh eetM etal

B lo w m o ld ingC as tingC om press io n m old ingE xtru s ionIn je c tio n M old ingT herm o form ingT ra nsfe r m o ld ing

Po lym erProcesses

B o ringD ril lingFa cingG r ind ingM ill ingP lan ingT u rn ingSa w ingE C M , E D M

M ach in ing

A no d iz ingH on ingPa in tingP la t ingPo lish ing

F in ish ing

A utom atedB o nd ingB raz ingM an ualR ive t ingSo ld e r ingW eld ing

A ssem bly

M anu fac tu r ingProcesses

protection?

BAB 1 ASPEK-ASPEK MANUFAKTUR

MANUFACTURING• Manufacturing is not only the making of products• Integration

– Product demand– Product design– Material selection– Manufacturing processing– Product assembly– Management

DESIGN• The Accreditation Board for Engineering and

Technology (ABET) defines engineering design as: ‘‘the process of devising a system, component or process to meet desired needs.’’

• Design is an iterative decision-making process

DESIGN PROCESSIdentifying user needs Concept development

Synthesis

Analysis/Optimization

Evaluation/PrototypingManufacturing ProcessPlanning

CONCURRENT ENGINEERING• 1987: a U.S. Defense Advanced Research Projects

Agency (DARPA) working group • Definition:

‘‘Concurrent Engineering (CE) is a systematic approach to the integrated (concurrent) design of products and their manufacturing and support process.’’

• The need for accelerated product launch in the face of significantly shortened product life cycles

DESIGN FOR MANUFACTURING• Consideration of manufacturing (also termed

as production or fabrication) processes during the design stage of a product is fundamental to successful design.

• Since selection of materials must precede consideration and analysis of manufacturability.

Design for Manufacturing• Design for Casting• Design for Forging• Design for Machining• Design for Injection Molding• Design for Assembly• others

Design for Forging

Design for Machining

Material Selection and Material Processing in Design

New Product Analysis• Everyday we use thousands of different products, from telephones

to bikes and drinks cans to washing machines and microwaves. • But have you ever thought about how they work or the way they

are made?• Every product is designed in a particular way - product

analysis enables us to understand the important materials, processing, economic and aesthetic decisions which are required before any product can be manufactured.

• An understanding of these decisions can help us in designing and making for ourselves.

Getting Started

• The first task in product analysis is to become familiar with the product! What does it do? How does it do it? What does it look like?

• All these questions, and more, need to be asked before a product can be analysed.

• As well as considering the obvious mechanical (and possibly electrical) requirements, it is also important to consider the ergonomics, how the design has been made user-friendly and any marketing issues - these all have an impact on the later design decisions.

Let's take the example of a bike

• What is the function of a bicycle?• How does the function depend on the type of bike (e.g.

racing, or about-town, or child's bike)?• How is it made to be easily maintained?• What should it cost?• What should it look like (colours etc.)?• How has it been made comfortable to ride?• How do the mechanical bits work and interact?

How would we manufacture a bike ?

TopTube

RearDerailleur

Front BrakeRear Brake

SaddleSeatPost

Pedal

Handle Bar

DownTube

Fork

(Courtesy of Trek Bicycle, 2002)

Systems and Components• There are 2 main types of product - those

that only have one component (e.g. a spatula) and those that have lots of components (e.g. a bike).

• Products with lots of components we call systems. For example:

System Components

Product Components

Bike Frame, wheels, pedals, forks, etc.

Drill Case, chuck, drill bit, motor, etc.

Multi-gym Seat, weights, frame, wire, handles, etc.

Product Analysis• In product analysis, we start by considering

the whole system. • But, to understand why various materials

and processes are used, we usually need to 'pull it apart' and think about each component as well.

• We can now analyse the function in more detail and draft a design specification.

Some important design questions

• To build a design specification, consider questions like the following:– What are the requirements on each part (electrical, mechanical,

aesthetic, ergonomic, etc)?– What is the function of each component, and how do they

work?– What is each part made of and why?– How many of each part are going to be made?– What manufacturing methods were used to make each part and

why ?– Are there alternative materials or designs in use and can you

propose improvements?

Design Questions• These are only general questions, to act as a guide - you will need to

think of the appropriate questions for the products and components you have to analyse. For a drinks container, a design specification would look something like:

– provide a leak free environment for storing liquid– comply with food standards and protect the liquid from health hazards– for fizzy drinks, withstand internal pressurisation and prevent escape of bubbles– provide an aesthetically pleasing view or image of the product– if possible create a brand identity– be easy to open– be easy to store and transport– be cheap to produce for volumes of 10,000+

Choosing the Right Materials• Given the specification of the requirements

on each part, we can identify the material properties which will be important - for example:

Choosing the Right Materials

Requirement Material Property

must conduct electricity electrical conductivity

must support loads without breaking strength

cannot be too expensive cost per kg

Material Selection

• One way of selecting the best materials would be to look up values for the important properties in tables. But this is time-consuming, and a designer may miss materials which they simply forgot to consider.

• A better way is to plot 2 material properties on a graph, so that no materials are overlooked - this kind of graph is called a materials selection chart (these are covered in another part of the tutorial).

• Once the materials have been chosen, the next step is normally to think about the processing options.

Choosing the Right Process

• It is all very well to choose the perfect material, but somehow we have to make something out of it as well! An important part of understanding a product is to consider how it was made - in other words what manufacturing processes were used and why.

• There are 2 important stages to selecting a suitable process:– Technical performance: can we make this product with the material

and can we make it well?– Economics: if we can make it, can we make it cheaply enough?

• Process selection can be quite an involved problem - we deal with one way of approaching it in another part of the tutorial.

• So, now we know why the product is designed a particular way, why particular materials are used and why the particular manufacturing processes have been chosen.

• Is there anything else to know?

Wrap Up…

• Product analysis can seem to follow a fixed pattern:– Think about the design from an ergonomic and

functional viewpoint.– Decide on the materials to fulfil the performance

requirements.– Choose a suitable process that is also economic.

• Whilst this approach will often work, design is really holistic - everything matters at once - so be careful to always think of the 'bigger picture'.

Example Analysis• Is the product performance driven or cost driven? • This makes a big difference when we choose materials. • In a performance product, like a tennis racquet, cost is one of the last

factors that needs to be considered. • In a non-performance product, like a drinks bottle, cost is of primary

importance - most materials will provide sufficient performance (e.g. although polymers aren't strong, they are strong enough).

• Although we usually choose the material first, sometimes it is the shape (and hence process) which is more limiting.

• With window frames, for example, we need long thin shaped sections - only extrusion will do and so only soft metals or polymers can be used (or wood as it grows like that!).

Choosing between Different Materials

• There are three main things to think about when choosing materials (in order of importance):– Will they meet the performance requirements?– Will they be easy to process?– Do they have the right 'aesthetic' properties?

• We deal with the processing aspects of materials in a different part of this course.

• For now it is sufficient to note that experienced designers aim to make the decisions for materials and processes separately together to get the best out of selection.

• The choice of materials for only aesthetic reasons is not that common, but it can be important: e.g. for artists.

• However, the kind of information needed is difficult to obtain and we won't deal with this issue further here.

Material Selection• Most products need to satisfy some performance targets, which we

determine by considering the design specification e.g. they must be cheap, or stiff, or strong, or light, or perhaps all of these things...

• Each of these performance requirements will influence which materials we should choose - if our product needs to be light we wouldn't choose lead and if it was to be stiff we wouldn't choose rubber!

• So what approach do we use to select materials?

Using Material Selection Charts• So what we need is data for lots of material

properties and for lots of materials. • This information normally comes as tables of

data and it can be a time-consuming process to sort through them.

• And what if we have 2 requirements - e.g. our material must be light and stiff - how can we trade-off these 2 needs?

• The answer to both these problems is to use material selection charts.

• Here is a materials selection chart for 2 common properties: Young's modulus (which describes how stiff a material is) and density.

Using Material Selection Charts

• On these charts, materials of each class (e.g. metals, polymers) form 'clusters' or 'bubbles' that are marked by the shaded regions.

• We can see immediately that:– metals are the heaviest materials,– foams are the lightest materials,– ceramics are the stiffest materials.

• But we could have found that out from tables given a bit of time, although by covering many materials at a glance, competing materials can be quickly identified.

• Where selection charts are really useful is in showing the trade-off between 2 properties, because the charts plot combinations of properties.

• For instance if we want a light and stiff material we need to choose materials near the top left corner of the chart - so composites look good.

• Note that the chart has logarithmic scales - each division is a multiple of 10; material properties often cover such huge ranges that log scales are essential.

Using Material Selection Charts

• To find the best materials we need to use the Young's modulus - density chart from amongst the available charts. The charts can be annotated to help reveal the 'best' materials, by placing a suitable selection box to show only stiff and light materials.

• What can we conclude?• The values of Young's modulus for polymers are low, so

most polymers are unlikely to be useful for stiffness-limited designs.

• Cambridge Engineering Selector (CES) is the Software used for Material Selection developed by Prof. Ashby.

• Other material property selection charts include:

Wrap Up• By considering 2 (or more) charts, the properties needed to satisfy the

main design requirements can be quickly assessed.• The charts can be used to identify the best classes of materials, and

then to look in more detail within these classes.• There are many other factors still to be considered, particularly

manufacturing methods. The selection made from the charts should be left quite broad to keep enough options open.

• A good way to approach the problem is to use the charts to eliminate materials which will definitely not be good enough, rather than to try and identify the single best material too soon in the design process.

PROCESS-MATERIAL MATRIX

General classification of shape

PROCESS-SHAPE MATRIX

PROCESS-MASS MATRIX

PROCESS-SECTION THICKNESS MATRIX

PROCESS-TOLERANCE LIMIT MATRIX

PROCESS-SURFACE ROUGHNESS MATRIX

CHAPTER 7

86

Manufacturing Process Selection and Design

Overview

• Process Selection– Types of Processes– Process Flow Structures– Product-Process Matrix

• Break-Even Analysis

• Manufacturing Process Flow Design

87

88

Process Selection

89

Process and Process Selection• Process: Any set of activities performed by an

organization that takes inputs and transforms them into outputs ideally of greater value to the organization than the original inputs.

• Process selection refers to the strategic decision of selecting with which kind of production processes to have in the manufacturing plant.

Process SelectionThree primary questions:

• How much variety in products or services will the system need to handle?

• What degree of equipment flexibility will be needed?

• What is the expected volume of output?

90

Types of ProcessesBased on what they do• Conversion process

Iron ore steel sheets, ingredients of toothpaste toothpaste

• Fabrication process: changing raw materials into some specific form Sheet metal car fender, gold a crown for a tooth, cloth

clothes • Assembly process

Assemble parts to components, put toothpaste tubes into a box, fasten a dental crown into someone’s mouth

• Testing process For quality of products

91

Process Types

A process flow structure refers to how a factory organizes material flow using one or more of the process technologies.

• Job shop

• Batch shop

• Assembly Line

• Continuous Flow

92

Job Shop

• Job shop: A process structure suited for low-volume production of a great variety of nonstandard products.– Each job may require a different set or sequence of processing steps

– High flexibility of equipment (General-purpose equipment )

– Skilled workers

– Examples: commercial printing firms, copy center making a single copy of a student term paper, airplane manufacturers, machine tool shops, American Chopper

93

Batch Shop• Batch shop: A process structure that produces a moderate

variety of standard products at relatively low volumes.– A somewhat standardized job shop– Employed when a business has a relatively stable line of products– The products are produced periodically in batches to reduce the impact

of setup time on equipment– The equipment need NOT be as flexible as in a job shop– The skill level of workers need NOT to be as high as in a job shop– Examples:

• Bakeries: make bread, cakes, cookies in batches;• Movie theatre: shows movies to groups (batches) of people;• Airlines: carry batches of people from airport to airport;• Other examples: production of beer, book, magazine, etc

94

Assembly Line

• Assembly line (Repetitive processing): A process structure designed to make discrete parts moving

through a set of specially designed workstations at a controlled rate.– High volume– Standardized products– Slight flexibility of equipment– Skill of workers is usually low– Examples: manual assembly of toys and appliances, automatic

assembly of components on a printed circuit board, production line (automobiles, computers, etc.)

95

Example: Production Line

96

Continuous Flow

• Continuous flow: An often automated process structure that converts raw materials into finished product in one continuous process.– Highly standardized products, no variety– Special-purpose equipment (no need for equipment flexibility)– Skill of workers is low– Examples: petroleum, steel, sugar, flour, and salt

97

Example: Continuous Flow

98

Product-Process Matrix

• Choice of process flow structure is based on two main considerations:– Variety—how much the product changes from customer to customer;– Volume of demand.

• Product-process matrix: Shows the relationship between process structures and product volume and variety characteristics.

• As volume increases and the product line narrows, specialized equipment and standardized material flows become economically feasible. (see next slide)

99

Product-Process Matrix

100

Exhibit 7.1

Volume

Variety

HighLow

High

Low

101

Break-Even Analysis

Break-Even Analysis

• A standard approach to choosing among alternative processes or equipment.

• Most suitable when processes and equipment entail a large initial investment and fixed cost, and when variable costs are reasonably proportional to the number of units produced.

• Break-even Point (BEP)– One option case: determine the point in units (produced and sold) at

which total cost = total revenue. – Multiple options case: determine the points in units at which one

option is indifferent to another.

102

Cost-Volume Relationships (Total Cost)

103

Amou

nt (

$)

0Q (Quantity in units)

Total cost =

VC + FC

Variable cost (

VC)

Fixed cost (FC)

Total cost (TC) = Fixed cost (FC) + Variable cost (VC) = Fixed cost (FC) + Unit cost (v) X Quantity (Q)

Revenue-Volume Relationships (Total Revenue)

104

Am

ount

($)

Q (Quantity in units)0

Total re

venue

Total revenue = Revenue per unit (R) X Quantity (Q)

Cost-Volume Relationships (BEP)

105

Am

ount

($)

Q (volume in units)0 BEP

+ Profit

Total

reve

nue

Total cost

- Loss

Break-even point (BEP): the quantity of output at which total cost and total revenue are equal.

106

Total Revenue (TR) = Total Cost (TC)

Total Revenue = Total Fixed Cost + Total Variable Cost

Unit Revenue* Units = Total Fixed Cost + Unit Cost* Units

R * Q = FC + v * Q

Break Even Quantity: QBEP = FC / (R – v)

One-Option Case

Profit (margin) = Total Revenue – Total Cost

Find out the quantity that makes:

Example -- One-Option Case

Suppose you want to purchase a new computer that will cost $5,000. It will be used to process written orders from customers who will pay $25 each for the service. The cost of labor, electricity and the form used to place the order is $5 per customer.

• How many customers will we need to serve to permit the total revenue to break-even with our costs?

FC = $5,000, R = $25/customer, v = $5/customer Break-even quantity QBEP:

= FC /(R-v) = 5,000/(25-5) = 250 customers

• How many customers should we serve to make a profit of $1,000? Profit = Total Revenue – Total Cost

= R * Q – (FC + v * Q) = (R-v) * Q - FC 1,000 = (25-5) * Q – 5,000

Q = 300 customers

107

Example -- Multiple-Option Case (page 207)

108

Suppose a manufacturer has identified the following options for obtaining a machined part: 1. purchase the part $200/unit, no fixed cost 2. make the part on a semiautomatic lathe $75/unit, fixed cost = $80,000 3. make the part on a machining center $15/unit, fixed cost = $200,000

Which option should the manufacturer choose? TC_buy = 200 * QTC_lathe = 80,000 + 75 * QTC_machine = 200,000 + 15 * Q


109

0

100000

200000

300000

400000

500000

0 300 600 900 1200 1500 1800 2100 2400

TC_buyTC_LatheTC_Machine

Demand < B BuyB < Demand < A Semiautomatic LatheDemand >A Machine center

B

A

TC_buy

TC_Machine

TC_Lathe

Minimum cost


• Break-even point B: Total cost of “buy” = Total cost of “Make on lathe” 200 x Demand = 80,000 + 75 x Demand DemandB = 80,000/(200-75) = 640 units

• Break-even point A: Total cost of “Make on lathe” = Total cost of “Make on machine” 80,000 + 75 x Demand = 200,000 + 15 x Demand DemandA= (200,000- 80,000)/(75-15) = 2,000 units

110

111

Manufacturing Process Flow Design

Manufacturing Process Flow Design

• A process flow design can be defined as a mapping of the specific processes that raw materials, parts, and subassemblies follow as they move through a plant.

• The most common tools to conduct a process flow design include assembly drawings, assembly charts, operation and route sheets, and process flowcharts.

112

Assembly Drawing

• An assembly drawing is simply an exploded view of the product showing its component parts.

113

Plug assembly drawing

Assembly Chart

• An assembly chart uses the information presented in the assembly drawing and defines how parts go together, their order of assembly, and often the overall material flow pattern.

114

Assembly chart for plug assembly

Operation and Route Sheet• An operation and route sheet specifies operations and process

routing for a particular part. It conveys such information as the type of equipment, tooling, and operations required to complete the part.

115

Operation and route sheet for plug assembly

Process Flowchart• A process flowchart denotes what happens to the product as it

processes through the productive facility.

116

Process flowchart for plug housing

Recap– Process

– Process selection

– Types of processes

– Process flow structures• Job shop

• Batch shop

• Assembly line

• Continuous flow117

Product-process matrixBreak-even point (BEP)

One-option caseMultiple-option case

Manufacturing process flow design

Manufacturing process decisions• How do we choose the specific manufacturing

processes? • How do the selected materials influence the choice

of manufacturing processes? • Would product function or performance issues

influence our choice of processes?• What criteria should we use to select processes? • Which criteria are more important? • Who will make the final decisions?

Parts undergo sequence of processes• Primary - alter the (“raw”) material’s basic shape or form.

Sand castingRollingForgingSheet metalworking

• Secondary - add or remove geometric features from the basic forms Machining of a brake drum casting (flat surfaces)Drilling/punching of refrigerator housings (sheet metal)Trimming of injection molded part flash

• Tertiary - surface treatments PolishingPaintingHeat-treatingJoining

Part / Mfg. Process Considerations

1. Production Volume2. Part Size (overall)3. Shape Capability (features) boss/depression 1D boss/depression >1D holes undercuts (int./ext.) uniform walls cross sections - uniform/regular rotational symmetry captured cavities

Is process capable of producing part geometry?

ManufacturingProcesses

ProductGeometry

“capable”geometry & processes

Process-first selection approach

Part Information1. Production Volume (run qty)2. Part Size (overall)3. Shape Capability (features)

boss/depression 1Dboss/depression >1Dholesundercuts (int./ext.)uniform walls

uniform cross sectionsregular cross sectionsrotational symmetrycaptured cavities

Axis of rotation (symmetry)

Shape generation capability (of processes)ME 488/588 Design for Manufacture & Assembly Process Capabilitites for Shape Generation Date: 9/2/03Engineer: R. J. E. Design Part Name: no features part For Process

Part Data Input: N N N N N N N N N Assembly Evaluation

Processes Shap

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Dep

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Dep

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Solidification sand casting Y Y YU Y Y Y Y N N 4 3 1 8 0 0 Ainvestment casting Y Y YU Y Y Y Y N N 5 5 2 12 0 0 Adie casting Y Y YU Y Y Y N N N 4 5 3 12 0 0 Ainjection molding Y Y YU Y Y Y N N N 5 5 5 15 0 0 Astructural foam Y Y YU Y Y Y N N N 4 4 3 11 0 0 Ablow molding - extr Y Y M N Y Y M Y N 3 4 3 0 0 2 Rblow molding - inj Y Y M N Y YU M N N 3 4 3 0 0 2 Rrotational molding Y Y M N Y Y N M N 2 2 1 0 0 2 R

Bulk impact extrusion Y N Y N Y YU N N Y 3 3 1 7 0 0 ADeformation cold heading Y N Y N Y YU N N Y 3 3 1 7 0 0 A

closed die forging Y Y Y Y Y Y N N N 3 2 1 6 0 0 Apowder metal Y N Y YU Y Y N N YU 3 3 1 7 0 0 Ahot extrusion Y N Y M Y Y N N Y 2 2 3 0 0 1 Rrotary swaging N N N N M N N N N 1 1 1 0 0 1 R

Metal machined from stock Y Y Y Y Y Y Y N Y 2 3 2 7 0 0 ARemoval ECM Y Y Y Y Y Y N N N 3 4 1 8 0 0 A

EDM Y Y Y Y Y Y N N N 3 4 1 8 0 0 A

Profile Generation Wire EDM Y N Y Y Y Y N N Y 2 2 3 7 0 0 A

Sheet sheet metal bending Y Y M Y Y Y N N N 4 3 4 0 0 1 RForming thermoforming Y Y M Y Y Y N N N 3 3 3 0 0 1 R

metal spinning N N M N M N Y N N 1 1 1 0 0 2 R© R. J. Eggert, BSU (Based on data from Boothroyd, Dewhurst & Knight) revision 9/02/03

Design & Manufacturing Concerns:Tolerance, Inspection, Quality Control

In terchangeability of Parts

What do the following have in common?- Fuel pump on a car- Printer cartridge- Light bulb

Modern manufacturing depends on interchangeability

Interchangeably depends on size control

For Size Control

Need

Standard unit of length (meter)

Suitable measuring equipment (gageblocks, dial gages, calipers, steel rules,etc.)

Inspection of parts producedQuality Control

Tolerances

Dimensions assigned based onfunctionality requirements and/or designspecifications..Mass-produced parts cannot all beproduced to exact (specified) dimensions.Always variations in dimensions.Due to:Tool and die wear.Changes in processing conditions.Variability in raw material composition andpurity.

Tolerances (TJ- continued

Ta: designer-specified allowed variation in adimension or other geometric characteristic.Every process has standard or commercialtolerances.Tightest Ta are achievable via machining.

In injection molding variations in temperatureand pressure, non-uniform shrinkage,sensitivity of material used, etc affect Ta

In stamping, springback affects Ta

Tolerances (TJ- continued

To achieve functionality designers canlimit range of acceptable dimensionalvariations of parts.The more strict the limitations,the more dimensions subjected to specialtolerance limitations, the more costly thepart.Parts with no Ta tighter than standard areleast costly "Best to consult vendors and industrypublications for""a data.

Internationally Accepted (ISO)Definitions

Limits of s\ze:The two extreme permissiblesizes of a part between which the actual sizemust lie.Example: hole diameter (d)dIT = 50.05 mm (max limit of size);dmir= 49.95 mm (min limit of size)Tolerance (Ta): differencemaximum limit of size and the minimum limitof size.Example: Ta = 50.05-49.95 = 0.10 mm

(ISO) Definitions - continued

Basic Size: The size by reference towhich the limits of size are fixed. Canbe assigned to a hole or shaft.Example:

- Given: Basic size (dia.) of hole = 50mm

_ l

Limits of size: d—

50

(ISO) Definitions - continued+0.10-0.00

- Alternatively: d = 49.95

When parts must fit together (a shaftinside a hole) the tolerances on both partsmust be considered simultaneously.Fit: relationship resulting from thedifference, before assembly, between thesizes of the two parts to be assembled.

Example:dj = hole diameterds = shaft diameterClearance exists if dh>ds

(allows for rotation and sliding of assembled parts)

Interference exists if dh<ds

(allows alignment of parts; provides stiffness)

Fits - continued+0.10 +005

-0.00 -0.05

d, = 50.00 d, = 50.00

Clearance Fit: exists if the min. holediameter > max shaft diameter.Inference I it: exists if the max holediameter < min shaft diameter.

Transitional Fit: exists if sometimes getclearance and sometimes getinterference.

Allowance

" he intentional desired difference between thedimensions of two mating parts.""he difference between the dimensions of thelargest interior-itting part and the smallestexterior-fitting part.

Clearance t: allowance = min clearance.Interference fit: allowance =

Inspection and QC

To ensure that dimensions and tolerancesare being metNeed

Inspection - to determine how well thephysical specifications are being met.

Quality Control - the amount of inspectionnecessary to produce an acceptable part.

Procedure of Measurement andmodeling in your design projects1- Chose the right unit system

2- Chose the right measurement device

3- Nominal dimensions: measure each feature with itscorresponding mating feature at the same time. Thenominal values of two feature should be equal. Roundthe numbers to a value with not many decimal point.4- Tolerances: select the allowance based on the fittingtype. Measure each feature several times and measureseveral features. Estimate the tolerance using theestimated allowance and average of the measurementresults.

Inspection and QC - continued

Inspection of all parts is too $$$$$We want to detect if a process is goingout of control BEFORE defective partsappear.Want to detect assignable causevariations i.e. malfunction of people andmachines, or defective materials, (toolwear, die wear, people wear, etc.)Not normal chance variations due to non-uniformity of materials, equipment, etc.

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BAB 3 PEMBENTUKAN LOGAM

PROSES PRODUKSI I

Module 8 142

Metal Forming

• Metal forming includes a large group of manufacturing processes in which plastic deformation is used to change the shape of metal work pieces

• Plastic deformation: a permanent change of shape, i.e., the stress in materials is larger than its yield strength

• Usually a die is needed to force deformed metal into the shape of the die

Module 8 143

• Metal with low yield strength and high ductility is in favor of metal forming

• One difference between plastic forming and metal forming is

Plastic: solids are heated up to be polymer melt

Metal: solid state remains in the whole process

- (temperature can be either cold, warm or hot)

Metal Forming

Module 8 144

1. General mechanics principle

• The underlying mechanics principle for metal forming is the stress-strain relationship; see Figure 1.

Figure 1

Module 8 145

• True strain: Instantaneous elongation per unit length of the material

0ln

0 LL

LdLL

L

L0: the initial length of a specimen

L: the length of the specimen at time t

the true strain at time t

• True Stress: Applied load divided by instantaneous value of cross-section area

AF /

Module 8 146

• In the forming process we are more interested in the plastic deformation region (Figure 1)

Plastic deformation region

Module 8 147

• The stress-strain relationship in the plastic deformation region is described by

nK Where K= the strength coefficient, (MPa) = the true strain, σ=the true stress n= the strain hardening exponent,

The flow stress (Yf) is used for the above stress (which is the stress beyond yield)

Called FLOW CURVE

Module 8 148

• As deformation occurs, increasing STRESS is required to continue deformation (shown in curve)

• Flow Stress: Instantaneous value of stress required to continue deforming the material (to keep metal “flowing”)

FLOW STRESS

nKfY

Module 8 149

• For many bulk deforming processes, rather than instantaneous stress, average stress is used (extrusion)

• The average flow stress can be obtained by integrating the flow stress along the trajectory of straining, from zero to the final strain value defining the range of interest

nkY

n

f

1

AVERAGE FLOW STRESS

Average flow stress Max. strain during deformation

Strength Coefficient

Strain hardening exponent

Module 8 150

Example 1:Determine the value of the strain-hardening exponent for a metal that will cause the average flow stress to be three-quarters of the final flow stress after deformation.

According to the statement of the problem, we have

4/3fY of fY

333.075.0)1/(1

75.0)1/(

75.0

nn

KnK

YYnn

ff

Module 8 151

• The above analysis is generally applicable to the cold working, where the temperature factor is not considered.

• The metal forming process has three kinds in terms of temperature: (1) cold, (2) warm, (3) hot

• In the case of warm and hot forming, the temperature factor needs to be considered, in particular

Temperature up The (yield) strength down and ductility up

Module 8 152

• Strain rate (related to elevated temperatures)- Rate at which metal is strained in a forming process- In the hot forming or warm forming, the strain rate can affect the

flow stress

hv /h

Speed of deformation (could be equal to velocity of ram)

Instantaneous height of work-piece being deformed

h

mf CY

Flow stress

Strain Rate

Module 8 153

mf CY

whereC strength constantm strain-rate sensitivity exponent

C and m are determined by the following figure which is generated from the experiment

nKfY

Strength coefficient but not the same as K

Module 8 154

Module 8 155

C and m are affected by temperature

Temperature Up

C Down

m Up

Module 8 156

mnf AY

Even in the cold work, the strain rate could affect the flow stress. A more general expression of the flow stress with consideration of the strain rate and strain is presented as follows:

A is a strength coefficient, a combined effect of K, C

All these coefficients, A, n, m, are functions of temperature

Module 8 157

Example 2:A tensile test is carried out to determine the strength constant C and strain-rate sensitivity exponent m for a certain metal at 1000oF. At a strain rate = 10/sec, the stress is measured at 23,000 lb/in2; and at a strain rate = 300/sec, the stress=45,000 lb/in2. Determine C and m

23000=C(10)^m45000=C(300)^m

From these two equations, one can find m=0.1973

Solution:

Temperature in Metal Forming • For any metal, K and n in the flow curve

depend on temperature– Both strength and strain hardening are reduced at

higher temperatures– In addition, ductility is increased at higher

temperatures

HOT AND COLD WORKING

HOT AND COLD WORKING

Cold working is metal forming performed at room temperature. Advantages: better accuracy, better surface finish, high strength and hardness of the part, no heating is required. Disadvantages: higher forces and power, limitations to the amount of forming, additional annealing for some material is required, and some material are not capable of cold working.

Warm working is metal forming at temperatures above the room temperature but bellow the recrystallization one.

Advantages: lower forces and power, more complex part shapes, no annealing is required. Disadvantages: some investment in furnaces is needed. Hot working involves deformation of preheated material at temperatures above the re crystallization

temperature. Advantages: big amount of forming is possible, lower forces and power are required, forming of materials with low ductility, no work hardening and therefore, no additional annealing is required. Disadvantages: lower accuracy and surface finish, higher production cost, and shorter tool life.

Friction in Metal Forming• In most metal forming processes, friction is

undesirable: – Metal flow is retarded – Forces and power are increased– Wears tooling faster

• Friction and tool wear are more severe in hot working

Lubrication in Metal Forming• Metalworking lubricants are applied to tool‑work

interface in many forming operations to reduce harmful effects of friction

• Benefits: – Reduced sticking, forces, power, tool wear– Better surface finish– Removes heat from the tooling

Considerations in Choosing a Lubricant

• Type of forming process (rolling, forging, sheet metal drawing, etc.)

• Hot working or cold working• Work material• Chemical reactivity with tool and work metals • Ease of application• Cost

DefinitionsPlastic Deformation ProcessesOperations that induce shape changes on the work piece by plastic deformation under forces appliedby various tools and dies.

Bulk Deformation Processes These processes involve large amount of plastic deformation. The cross-section of workpiece changes

without volume change. The ratio cross-section area/volume is small. For most operations, hot or warm working conditions are preferred although some operations are carried out at room temperature.

Sheet-Forming Processes In sheet metalworking operations, the cross-section of work piece does not change—the material is only

subjected to shape changes. The ratio cross-section area/volume is very high. Sheet metalworking operations are performed on thin (less than 6 mm) sheets, strips or coils of metal by

means of a set of tools called punch and die on machine tools called stamping presses. They are always performed as cold working operations.

Module 8 165

Metal forming is divided into: (1) bulk and (2) sheet

Metal Forming

Bulk: (1) significant deformation

(2) massive shape change

(3) surface area to volume of the work is small

Sheet: Surface area to volume of the work is large

Module 8 166

Bulk deformation processes

RollingForging

Extrusion Drawing

Traditionally Hot

Module 8 167

Sheet deformation processes (Press working/ Stamping)

BendingDrawing

Shearing

Actually Cutting

BULK DEFORMATION PROCESSES IN METALWORKING

• Rolling• Other Deformation Processes Related to

Rolling• Forging• Other Deformation Processes Related to

Forging• Extrusion• Wire and Bar Drawing

ISE 316 - Manufacturing Processes Engineering

Bulk DeformationMetal forming operations which cause significant

shape change by deformation in metal parts whose initial form is bulk rather than sheet

• Starting forms: cylindrical bars and billets, rectangular billets and slabs, and similar shapes

• These processes work by stressing metal sufficiently to cause plastic flow into desired shape

• Performed as cold, warm, and hot working operations


Why do we use bulk processes?

• Produces common shapes inexpensively• Good mechanical properties

Common shapes

Basic principle

v, F

Reduction in size

• Push or pull• Single shot or

continuous• Hot or cold

• Malleable material• Refine and redirect the

grain• Alters geometry• Alters material

property

Importance of Bulk Deformation

• In hot working, significant shape change can be accomplished

• In cold working, strength can be increased during shape change

• Little or no waste - some operations are near net shape or net shape processes – The parts require little or no subsequent

machining


Four Basic Bulk Deformation Processes

1. Rolling – slab or plate is squeezed between opposing rolls

2. Forging – work is squeezed and shaped between between opposing dies

3. Extrusion – work is squeezed through a die opening, thereby taking the shape of the opening

4. Wire and bar drawing – diameter of wire or bar is reduced by pulling it through a die opening


Deformation process in which work thickness is reduced by compressive forces exerted by two opposing rolls


Figure 19.1 ‑ The rolling process (specifically, flat rolling)

ROLLING

The Rolls The rotating rolls perform two main functions:• Pull the work into the gap between them by

friction between workpart and rolls• Simultaneously squeeze the work to reduce

cross section


Types of Rolling• By geometry of work:

– Flat rolling - used to reduce thickness of a rectangular cross‑section

– Shape rolling - a square cross‑section is formed into a shape such as an I‑beam

• By temperature of work:– Hot Rolling – most common due to the large amount

of deformation required– Cold rolling – produces finished sheet and plate stock


Figure 19.2 ‑ Some of the steel products made in a rolling mill


Figure 19.3 ‑ Side view of flat rolling, indicating before and after thicknesses, work velocities, angle of contact with rolls, and other

features


Flat rolling• A strip of thickness ho enters the roll gap and is

reduced to hf by a pair of rotating• Rolling parameters:

– Initial thickness, ho

– Final thickness, hf

– Roll gap (usually same with hf)– Surface speed of the roll, Vr

– Initial velocity of the strip, Vo

– Final velocity of the strip, Vf

Flat RollingDraft = amount of thickness reduction


fo ttd

where d = draft; to = starting thickness; and tf = final thickness

Reduction = draft expressed as a fraction of starting stock thickness:

otdr

where r = reduction

Flat rolling• Rolling parameters (continued):

– Frictional force, fho – hf = 2R

– Roll force, FF = L w Yavg

– PowerPower = (2 F L N)/60000 ... kW

True Stress-strain Curves

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Figure 2.6 True stress-strain curves in tension at room temperature for various metals. The curves start at a finite level of stress: The elastic regions have too steep a slope to be shown in this figure, and thus each curve starts at the yield stress, Y, of the material

Shape RollingWork is deformed into a contoured cross‑section

rather than flat (rectangular)• Accomplished by passing work through rolls

that have the reverse of desired shape • Products include:

– Construction shapes such as I‑beams, L‑beams, and U‑channels

– Rails for railroad tracks– Round and square bars and rods


Roll Forming (hot):I-beams

Kalpakjian

Lunchtime on a Crossbeam, Unknown, www.buffalogames.com www.civil.ubc.ca

Figure 19.5 ‑ A rolling mill for hot flat rolling; the steel plate is seen as the glowing strip extending diagonally from the lower left corner (photo courtesy of Bethlehem Steel

Company)


Rolling Mills• Equipment is massive and expensive• Rolling mill configurations:

– Two-high – two opposing large diameter rolls– Three-high – work passes through both directions– Four-high – backing rolls support smaller work

rolls– Cluster mill – multiple backing rolls on smaller rolls – Tandem rolling mill – sequence of two-high mills


Slab Production: Hot Rolling

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www.falckacciai.it www.beautifuliron.com

Color & Temp

Figure 19.6 ‑ Various configurations of rolling mills: (a) 2‑high rolling mill


Figure 19.6 ‑ Various configurations of rolling mills:

(b) 3‑high rolling mill ISE 316 - Manufacturing Processes Engineering


(c) four‑high rolling mill ISE 316 - Manufacturing Processes Engineering

Cluster Mill Multiple backing rolls allow even smaller roll diameters


Figure 19 6 ‑ Various configurations of rolling mills: (d) cluster mill

Tandem Rolling MillA series of rolling stands in sequence



(e) tandem rolling mill

Thread RollingBulk deformation process used to form threads on

cylindrical parts by rolling them between two dies • Most important commercial process for mass

producing bolts and screws • Performed by cold working in thread rolling machines • Advantages over thread cutting (machining):

– Higher production rates– Better material utilization– Stronger threads due to work hardening– Better fatigue resistance due to compressive stresses

introduced by rolling


Figure 19.7 ‑ Thread rolling with flat dies: (1) start of cycle, and (2) end of cycle


Thread-rolling for bolts: Rolled threads stronger than machined (and less expensive)

Kalpakjian

Ring RollingDeformation process in which a thick‑walled ring of

smaller diameter is rolled into a thin‑walled ring of larger diameter

• As thick‑walled ring is compressed, deformed metal elongates, causing diameter of ring to be enlarged

• Hot working process for large rings and cold working process for smaller rings

• Applications: ball and roller bearing races, steel tires for railroad wheels, and rings for pipes, pressure vessels, and rotating machinery

• Advantages: material savings, ideal grain orientation, strengthening through cold working


Figure 19.8 ‑ Ring rolling used to reduce the wall thickness and increase the diameter of a ring:

(1) start, and (2) completion of process


Rolling problems and defects• Problems:

– Roll deflection– Spreading

• Defects:– Wavy edges– Cracks– Alligatoring– Residual stress

ForgingDeformation process in which work is compressed

between two dies • Oldest of the metal forming operations, dating from

about 5000 B C • Components: engine crankshafts, connecting rods,

gears, aircraft structural components, jet engine turbine parts

• In addition, basic metals industries use forging to establish basic form of large components that are subsequently machined to final shape and size


Forging grain flow

Classification of Forging Operations

• Cold vs. hot forging: – Hot or warm forging – most common, due to the

significant deformation and the need to reduce strength and increase ductility of work metal

– Cold forging - advantage is increased strength that results from strain hardening

• Impact vs. press forging:– Forge hammer - applies an impact load – Forge press - applies gradual pressure


Types of Forging Dies• Open‑die forging - work is compressed between

two flat dies, allowing metal to flow laterally without constraint

• Impression‑die forging - die surfaces contain a cavity or impression that is imparted to workpart, thus constraining metal flow - flash is created

• Flashless forging - workpart is completely constrained in die and no excess flash is produced


Open-die Forging• The simplest forging process.The workpiece is placed

between two flat dies and reduced in height by compressing.

• Used for changing the microstructure from cast structure to a wrought structure

• Forging force:Yf = material flow stress = friction coefficientr = radiush = height

)3

21(2

hrrYF f

Deformation operation reduces height and increases diameter of work (similar to compression test)

Stages in Open-Die Forging

(a) forge hot billet to max diameter

(b) “fuller: tool to mark step-locations

(c) forge right side

(d) reverse part, forge left side

(e) finish (dimension control)

[source:www.scotforge.com]

Open‑Die Forging with No Friction

If no friction occurs between work and die surfaces, then homogeneous deformation occurs, so that radial flow is uniform throughout workpart height and true strain is given by:

where ho= starting height; and h = height at some point during compression

• At h = final value hf, true strain is maximum valueISE 316 - Manufacturing Processes Engineering

hholn

Figure 19.11 ‑ Homogeneous deformation of a cylindrical workpart under ideal conditions in an open‑die forging operation:

(1) start of process with workpiece at its original length and diameter, (2) partial compression, and (3) final size


Open-Die Forging with Friction• Friction between work and die surfaces

constrains lateral flow of work, resulting in barreling effect

• In hot open-die forging, effect is even more pronounced due to heat transfer at and near die surfaces, which cools the metal and increases its resistance to deformation


Figure 19.12 ‑ Actual deformation of a cylindrical workpart in open‑die forging, showing pronounced barreling:

(1) start of process, (2) partial deformation, and (3) final shape


Closed-die forging• The workpiece acquires the shape of the

die cavities, while being forged between two shaped dies.

• Forging force:F = k Yf A

where k = multiplying factor (table 14.1)Yf = flow stressA = projected area

Forging: Heat LossMetal near die surfaces are coolest, flow less

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erlangen.de www.freedomalloysusa.com

Range of k values Simple shapes, without flash 3 - 5

Simple shapes, with flash 5 - 8

Complex shapes, with flash 8 - 12

Impression‑Die ForgingCompression of workpart by dies with inverse of

desired part shape • Flash is formed by metal that flows beyond die

cavity into small gap between die plates • Flash must be later trimmed from part, but it serves

an important function during compression:– As flash forms, friction resists continued metal flow into

gap, constraining material to fill die cavity – In hot forging, metal flow is further restricted by cooling

against die plates


Impression‑Die Forging Practice

• Several forming steps often required, with separate die cavities for each step – Beginning steps redistribute metal for more

uniform deformation and desired metallurgical structure in subsequent steps

– Final steps bring the part to its final geometry – Impression-die forging is often performed

manually by skilled operator under adverse conditions


Sequence in impression‑die forging: (1) just prior to initial contact with raw workpiece, (2) partial compression, and (3) final die closure, causing flash to form in gap between die plates.

Impression-Die Forging

Forging die

Stages in Impression-die (Closed-Die) Forging

Impression‑Die Forging Advantages and Limitations

• Advantages compared to machining from solid stock:– Higher production rates– Conservation of metal (less waste)– Greater strength– Favorable grain orientation in the metal

• Limitations:– Not capable of close tolerances– Machining often required to achieve accuracies and

features needed, such as holes, threads, and mating surfaces that fit with other components


Flashless ForgingCompression of work in punch and die tooling

whose cavity does allow for flash• Starting workpart volume must equal die cavity

volume within very close tolerance • Process control more demanding than

impression‑die forging • Best suited to part geometries that are simple and

symmetrical • Often classified as a precision forging processISE 316 - Manufacturing Processes Engineering

Figure 19.10 ‑ Three types of forging (c) flashless forging


Figure 19.18 ‑ Flashless forging: (1)just before initial contact with workpiece, (2)partial compression, and (3)final punch and die closure


Forging Hammers (Drop Hammers)

• Apply an impact load against workpart - two types:– Gravity drop hammers - impact energy from falling

weight of a heavy ram – Power drop hammers - accelerate the ram by

pressurized air or steam • Disadvantage: impact energy transmitted

through anvil into floor of building • Most commonly used for impression-die forging


Figure 19.20 ‑ Drop forging hammer, fed by conveyor and heating units at the right of the scene

(photo courtesy of Chambersburg Engineering Company)


Figure 19.21 ‑ Diagram showing details of a drop hammer for impression‑die forging


Forging Presses• Apply gradual pressure to accomplish

compression operation - types:– Mechanical presses - converts rotation of drive

motor into linear motion of ram – Hydraulic presses - hydraulic piston actuates ram – Screw presses - screw mechanism drives ram


Forging Press

Hydraulic press Mechanical press with an eccentric drive: fasterSlow but high forceand low cost

Forging Presses

Kalpakjian Erie Press

Forging Presses

Knuckle-joint press Screw press Gravity drop hammer:Simplest

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Upsetting and HeadingForging process used to form heads on nails, bolts, and

similar hardware products • More parts produced by upsetting than any other

forging operation • Performed cold, warm, or hot on machines called

headers or formers • Wire or bar stock is fed into machine, end is headed,

then piece is cut to length • For bolts and screws, thread rolling is then used to

form threads ISE 316 - Manufacturing Processes Engineering

Figure 19.23 ‑ An upset forging operation to form a head on a bolt or similar hardware item The cycle consists of:

(1) wire stock is fed to the stop(2) gripping dies close on the stock and the stop is retracted (3) punch moves forward(4) bottoms to form the head


Figure 19.24 ‑ Examples of heading (upset forging) operations: (a) heading a nail using open dies(b) round head formed by punch (c) and (d) two common head styles for screws formed by die(e) carriage bolt head formed by punch and die


Swaging Accomplished by rotating dies that hammer a

workpiece radially inward to taper it as the piece is fed into the dies

• Used to reduce diameter of tube or solid rod stock

• Mandrel sometimes required to control shape and size of internal diameter of tubular parts


Figure 19.25 ‑ Swaging process to reduce solid rod stock; the dies rotate as they hammer the work In radial forging, the workpiece rotates while the dies remain in a fixed orientation as they hammer the work


TrimmingCutting operation to remove flash from workpart

in impression‑die forging • Usually done while work is still hot, so a

separate trimming press is included at the forging station

• Trimming can also be done by alternative methods, such as grinding or sawing


Figure 19.30 ‑ Trimming operation (shearing process) to remove the flash after impression‑die

forging


ExtrusionCompression forming process in which the work

metal is forced to flow through a die opening to produce a desired cross‑sectional shape

• Process is similar to squeezing toothpaste out of a toothpaste tube

• In general, extrusion is used to produce long parts of uniform cross-sections

• Two basic types of extrusion:– Direct extrusion– Indirect extrusion


Extrusion

Typical use: ductile metals (Cu, Steel, Al, Mg), Plastics, Rubbers

Common products:

Al frames of white-boards, doors, windows, …

Comments on Direct Extrusion • Also called forward extrusion • As ram approaches die opening, a small portion

of billet remains that cannot be forced through die opening

• This extra portion, called the butt, must be separated from extruded product by cutting it just beyond the die exit

• Starting billet cross section usually round, but final shape is determined by die opening


Extrusion:Hollow cross-sections: Use Mandrels

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Figure 19.32 ‑ (a) Direct extrusion to produce a hollow or semi‑hollow cross‑section; (b) hollow and (c) semi‑hollow cross‑ sections


Figure 19.33 ‑ Indirect extrusion to produce

(a) a solid cross‑section and (b) a hollow cross‑section


Comments on Indirect Extrusion

• Also called backward extrusion and reverse extrusion

• Limitations of indirect extrusion are imposed by the lower rigidity of hollow ram and difficulty in supporting extruded product as it exits die


General Advantages of Extrusion

• Variety of shapes possible, especially in hot extrusion – Limitation: part cross‑section must be uniform

throughout length • Grain structure and strength enhanced in cold

and warm extrusion • Close tolerances possible, especially in cold

extrusion • In some operations, little or no waste of material


Hot vs. Cold Extrusion• Hot extrusion - prior heating of billet to above

its recrystallization temperature – This reduces strength and increases ductility of

the metal, permitting more size reductions and more complex shapes

• Cold extrusion - generally used to produce discrete parts – The term impact extrusion is used to indicate high

speed cold extrusion ISE 316 - Manufacturing Processes Engineering

Extrusion RatioAlso called the reduction ratio, it is defined as

where rx = extrusion ratio; Ao = cross-sectional area of the starting billet; and Af = final cross-sectional area of the extruded section

• Applies to both direct and indirect extrusionISE 316 - Manufacturing Processes Engineering

f

ox A

Ar

Figure 19.36 ‑ (a) Definition of die angle in direct extrusion; (b) effect of die angle on ram force


Comments on Die Angle • Low die angle - surface area is large, leading

to increased friction at die‑billet interface – Higher friction results in larger ram force

• Large die angle - more turbulence in metal flow during reduction– Turbulence increases ram force required

• Optimum angle depends on work material, billet temperature, and lubrication


Comments on Orifice Shape of Extrusion Die

• Simplest cross section shape = circular die orifice

• Shape of die orifice affects ram pressure • As cross‑section becomes more complex,

higher pressure and greater force are required


Figure 19.37 ‑ A complex extruded cross‑section for a heat sink (photo courtesy of Aluminum Company of America)


Extrusion Presses• Either horizontal or vertical

– Horizontal more common • Extrusion presses - usually hydraulically

driven, which is especially suited to semi‑continuous direct extrusion of long sections

• Mechanical drives - often used for cold extrusion of individual parts


Wire and Bar Drawing Cross‑section of a bar, rod, or wire is reduced by

pulling it through a die opening • Similar to extrusion except work is pulled

through die in drawing (it is pushed through in extrusion)

• Although drawing applies tensile stress, compression also plays a significant role since metal is squeezed as it passes through die opening


Figure 19.41 ‑ Drawing of bar, rod, or wire


Area Reduction in DrawingChange in size of work is usually given by area

reduction:

where r = area reduction in drawing; Ao = original area of work; and Ar = final work


o

foA

AAr

Wire Drawing vs. Bar Drawing • Difference between bar drawing and wire

drawing is stock size – Bar drawing - large diameter bar and rod stock– Wire drawing - small diameter stock - wire sizes

down to 0.03 mm (0.001 in.) are possible • Although the mechanics are the same, the

methods, equipment, and even terminology are different


Drawing Practice and Products• Drawing practice:

– Usually performed as cold working– Most frequently used for round cross‑sections

• Products:– Wire: electrical wire; wire stock for fences, coat

hangers, and shopping carts – Rod stock for nails, screws, rivets, and springs – Bar stock: metal bars for machining, forging, and

other processes ISE 316 - Manufacturing Processes Engineering

Bar Drawing • Accomplished as a single‑draft operation ‑ the

stock is pulled through one die opening • Beginning stock has large diameter and is a

straight cylinder • This necessitates a batch type operation


Figure 19.42 ‑ Hydraulically operated draw bench for drawing metal bars


Wire Drawing• Continuous drawing machines consisting of

multiple draw dies (typically 4 to 12) separated by accumulating drums – Each drum (capstan) provides proper force to

draw wire stock through upstream die – Each die provides a small reduction, so desired

total reduction is achieved by the series – Annealing sometimes required between dies


Figure 19.43 ‑ Continuous drawing of wire


DRAWING TOOLS

• The most important tool in the drawing process is without doubt the drawplate.This consist of a plate of high grade steel into which similar shaped holes have been placed whose size in evenly reduced from one hole to another.

• The most common drawplate have round holes and are used to reduce the size of round wire.

Drawing wire with the draw tongs

drawbench

Features of a Draw Die• Entry region - funnels lubricant into the die to

prevent scoring of work and die • Approach - cone‑shaped region where drawing

occurs• Bearing surface - determines final stock size • Back relief - exit zone - provided with a back

relief angle (half‑angle) of about 30 • Die materials: tool steels or cemented carbides


Figure 19.44 ‑ Draw die for drawing of round rod or wire


Preparation of the Work for Wire or Bar Drawing

• Annealing – to increase ductility of stock• Cleaning - to prevent damage to work surface

and draw die• Pointing – to reduce diameter of starting end

to allow insertion through draw die


SHEET METALWORKING• Cutting Operations• Bending Operations• Drawing• Other Sheet Metal Forming Operations• Dies and Presses for Sheet Metal Processes• Sheet Metal Operations Not Performed on

Presses• Bending of Tube Stock


Sheet Metalworking DefinedCutting and forming operations performed on

relatively thin sheets of metal • Thickness of sheet metal = 0.4 mm (1/64 in) to

6 mm (1/4 in)• Thickness of plate stock > 6 mm • Operations usually performed as cold working


Sheet and Plate Metal Products

• Sheet and plate metal parts for consumer and industrial products such as – Automobiles and trucks – Airplanes – Railway cars and locomotives – Farm and construction equipment – Small and large appliances – Office furniture – Computers and office equipment


Advantages of Sheet Metal Parts

• High strength• Good dimensional accuracy• Good surface finish• Relatively low cost • For large quantities, economical mass

production operations are available


Sheet Metalworking Terminology

1. “Punch‑and‑die”– Tooling to perform cutting, bending, and drawing

2. “Stamping press” – Machine tool that performs most sheet metal

operations3. “Stampings”

– Sheet metal products


Three Major Categories of Sheet Metal Processes

1. Cutting – Shearing to separate large sheets; or cut part

perimeters or make holes in sheets2. Bending

– Straining sheet around a straight axis3. Drawing

– Forming of sheet into convex or concave shapes


Figure 20.1 ‑ Shearing of sheet metal between two cutting edges:

(1) just before the punch contacts work


CuttingShearing between two sharp cutting edges


(2) punch begins to push into work, causing plastic deformation



(3) punch compresses and penetrates into work causing a smooth cut surface



(4) fracture is initiated at the opposing cutting edges which separates the sheet


Shearing, Blanking, and Punching

Three principal operations in pressworking that cut sheet metal:

• Shearing• Blanking• Punching


ShearingSheet metal cutting operation along a straight

line between two cutting edges• Typically used to cut large sheets into smaller

sections for subsequent operations


Figure 20.3 ‑ Shearing operation: (a) side view of the shearing operation

(b) front view of power shears equipped with inclined upper cutting blade Symbol v indicates motion


Blanking and PunchingBlanking - sheet metal cutting to separate piece

from surrounding stock• Cut piece is the desired part, called a blank Punching - sheet metal cutting similar to

blanking except cut piece is scrap, called a slug

• Remaining stock is the desired part


Figure 20.4 ‑ (a) Blanking and (b) punching


Clearance in Sheet Metal Cutting

Distance between the punch and die• Typical values range between 4% and 8% of

stock thickness – If too small, fracture lines pass each other,

causing double burnishing and larger force – If too large, metal is pinched between cutting

edges and excessive burr results


Clearance in Sheet Metal Cutting

• Recommended clearance can be calculated by:

c = at where c = clearance; a = allowance; and t = stock

thickness

• Allowance a is determined according to type of metal


Allowance a for Three Sheet Metal Groups


Metal group a

1100S and 5052S aluminum alloys, all tempers 0.045

2024ST and 6061ST aluminum alloys; brass, soft cold rolled steel, soft stainless steel

0.060

Cold rolled steel, half hard; stainless steel, half hard and full hard

0.075

Punch and Die Sizes for Blanking and Punching

For a round blank of diameter Db: Blanking punch diameter = Db ‑ 2c Blanking die diameter = Db where c = clearance

For a round hole of diameter Dh: Hole punch diameter = Dh

Hole die diameter = Dh + 2cwhere c = clearance


Figure 20.6 ‑ Die size determines blank size Db; punch size determines hole size Dh.; c = clearance


Angular ClearancePurpose: allows slug or blank to drop through

die• Typical values: 0.25 to 1.5 on each side


Figure 20.7 ‑ Angular clearance

Cutting ForcesImportant for determining press size (tonnage)

F = S t L

where S = shear strength of metal; t = stock thickness, and L = length of cut edge


Bending Straining sheetmetal around a straight axis to

take a permanent bend


Figure 20.11 ‑ (a) Bending of sheet metal

Metal on inside of neutral plane is compressed, while metal on outside of neutral plane is stretched


Figure 20.11 ‑ (b) both compression and tensile elongation of the metal occur in bending

Types of Sheetmetal Bending• V‑bending - performed with a V‑shaped die• Edge bending - performed with a wiping die


V-Bending • For low production• Performed on a press brake• V-dies are simple and inexpensive


Figure 20.12 ‑ (a) V‑bending

Edge Bending • For high production• Pressure pad required• Dies are more complicated and costly


Figure 20.12 ‑ (b) edge bending

Stretching during Bending• If bend radius is small relative to stock

thickness, metal tends to stretch during bending

• Important to estimate amount of stretching, so that final part length = specified dimension

• Problem: to determine the length of neutral axis of the part before bending


Bend Allowance Formula

where BA = bend allowance; A = bend angle; R= bend radius; t = stock thickness; and Kba is factor to estimate stretching

• If R < 2t, Kba = 0.33 • If R 2t, Kba = 0.50ISE 316 - Manufacturing Processes Engineering

)( tKRABA ba360

2

Springback in BendingSpringback = increase in included angle of bent

part relative to included angle of forming tool after tool is removed

• Reason for springback:– When bending pressure is removed, elastic

energy remains in bent part, causing it to recover partially toward its original shape


Figure 20.13 ‑ Springback in bending shows itself as a decrease in bend angle and an increase in bend radius: (1) during bending, the work is forced to take the radius Rb and included angle Ab' of the bending tool (punch in V‑bending), (2) after punch is removed, the work springs back to radius R and angle A'


Bending Force

Maximum bending force estimated as follows:


where F = bending force; TS = tensile strength of sheet metal; w = part width in direction of bend axis; and t = stock thickness. For V- bending, Kbf = 1.33; for edge bending, Kbf = 0.33

DTSwtKF bf

2

Figure 20.14 ‑ Die opening dimension D: (a) V‑die, (b) wiping die


Drawing Sheet metal forming to make cup‑shaped,

box‑shaped, or other complex‑curved, hollow‑shaped parts

• Sheet metal blank is positioned over die cavity and then punch pushes metal into opening

• Products: beverage cans, ammunition shells, automobile body panels


Figure 20.19 ‑ (a) Drawing of a

cup‑shaped part: (1) start of operation

before punch contacts work

(2) near end of stroke

(b) Corresponding workpart:

(1) starting blank (2) drawn part


Aluminum Beverage Cans

Figure 16.38 (a) Aluminum beverage cans. Note the excellent surface finish. (b) Detail of the can lid showing integral rivet and scored edges for the pop-top.

(a)

Can Manufacture

Figure 16.31 The metal-forming processes involved in manufacturing a two-piece aluminum beverage can.

Clearance in Drawing• Sides of punch and die separated by a

clearance c given by:c = 1.1 t

where t = stock thickness• In other words, clearance = about 10% greater

than stock thickness


Drawing Ratio DR

where Db = blank diameter; and Dp = punch diameter

• Indicates severity of a given drawing operation– Upper limit = 2.0ISE 316 - Manufacturing

Processes Engineering

Most easily defined for cylindrical shape:

p

bDDDR

Reduction r

• Again, defined for cylindrical shape:


b

pb

DDD

r

• Value of r should be less than 0.50

Thickness‑to‑Diameter Ratio

Thickness of starting blank divided by blank diameter

Thickness-to-diameter ratio = t/Db

• Desirable for t/Db ratio to be greater than 1%• As t/Db decreases, tendency for wrinkling

increases


Blank Size Determination• For final dimensions of drawn shape to be

correct, starting blank diameter Db must be right

• Solve for Db by setting starting sheet metal blank volume = final product volume

• To facilitate calculation, assume negligible thinning of part wall


Shapes other than Cylindrical Cups

• Square or rectangular boxes (as in sinks), • Stepped cups, • Cones, • Cups with spherical rather than flat bases, • Irregular curved forms (as in automobile body

panels)

• Each of these shapes presents its own unique technical problems in drawing ISE 316 - Manufacturing


Other Sheet Metal Forming on Presses

Other sheet metal forming operations performed on conventional presses

• Operations performed with metal tooling• Operations performed with flexible rubber

tooling


Ironing • Makes wall thickness of cylindrical cup

more uniform• Examples: beverage cans and artillery

shells


Figure 20.25 ‑ Ironing to achieve a more uniform wall thickness in a drawn cup: (1) start of process; (2) during process Note thinning and elongation of walls

Embossing • Used to create indentations in sheet, such

as raised (or indented) lettering or strengthening ribs


Figure 20.26 ‑ Embossing: (a) cross‑section of punch and die configuration during pressing; (b) finished part with embossed ribs

Figure 20.28 ‑ Guerin process: (1) before and (2) afterSymbols v and F indicate motion and applied force respectively


Guerin Process

Advantages of Guerin Process• Low tooling cost• Form block can be made of wood, plastic, or

other materials that are easy to shape• Rubber pad can be used with different form

blocks • Process attractive in small quantity production


Dies for Sheet Metal ProcessesMost pressworking operations performed with

conventional punch‑and‑die tooling• Custom‑designed for particular part • The term stamping die sometimes used for

high production dies


Figure 20.30 ‑ Components of a punch and die for a blanking operation


Figure 20.31 ‑ (a) Progressive die; (b) associated strip

development


Figure 20.32 ‑ Components of a typical mechanical drive stamping press


Types of Stamping Press Frame• Gap frame – configuration of the letter C and

often referred to as a C‑frame• Straight‑sided frame – box-like construction

for higher tonnage


Figure 20.33 ‑ Gap frame press for sheet metalworking

(photo courtesy of E. W. Bliss Company)

Capacity = 1350 kN (150 tons)


Figure 20.34 ‑ Press brake with

bed width of 9.15 m (30 ft) and capacity of 11,200 kN (1250 tons); two workers are positioning plate stock for bending

(photo courtesy of Niagara Machine & Tool Works)


Figure 20.35 ‑ Several sheet metal parts produced on a turret press, showing variety of hole shapes possible

(photo courtesy of Strippet, Inc.)


Figure 20.36 ‑ Computer numerical control turret press (photo courtesy of Strippet, Inc.)


Figure 20.37 ‑Straight‑sided frame press (photo courtesy Greenerd

Press & Machine Company, Inc.)


Power and Drive Systems• Hydraulic presses - use a large piston and

cylinder to drive the ram– Longer ram stroke than mechanical types– Suited to deep drawing– Slower than mechanical drives

• Mechanical presses – convert rotation of motor to linear motion of ram– High forces at bottom of stroke– Suited to blanking and punching


Sheet Metal Operations Not Performed on Presses

• Stretch forming• Roll bending and forming• Spinning• High‑energy‑rate forming processes.


Stretch Forming Sheet metal is stretched and simultaneously

bent to achieve shape change


Figure 20.39 ‑ Stretch forming: (1) start of process; (2) form die is pressed into the work with force Fdie, causing it to be stretched and bent over the form. F =

stretching force

Force Required in Stretch Forming

where F = stretching force; L = length of sheet in direction perpendicular to stretching; t = instantaneous stock thickness; and Yf = flow stress of work metal

• Die force Fdie can be determined by balancing vertical force componentsISE 316 - Manufacturing


fLtYF

Roll Bending Large metal sheets and plates are formed

into curved sections using rolls


Figure 20.40 ‑ Roll bending

Roll Forming Continuous bending process in which

opposing rolls produce long sections of formed shapes from coil or strip stock


Figure 20.41 ‑ Roll forming of a continuous channel section:

(1) straight rolls(2) partial form (3) final form

SpinningMetal forming process in which an axially

symmetric part is gradually shaped over a rotating mandrel using a rounded tool or roller

• Three types: 1. Conventional spinning2. Shear spinning3. Tube spinning


Figure 20.42 ‑ Conventional spinning: (1) setup at start of process; (2) during spinning; and (3) completion of process


www.dissco.co.nz

SpinningIdeal for • Lower production volumes• Large parts• Inexpensive tooling

www.traditional-building.com

www.ashfordmetalspinning.co.uk

High‑Energy‑Rate Forming (HERF)

Processes to form metals using large amounts of energy over a very short time

• HERF processes include: – Explosive forming– Electrohydraulic forming– Electromagnetic forming


Explosive FormingUse of explosive charge to form sheet (or plate)

metal into a die cavity • Explosive charge causes a shock wave whose

energy is transmitted to force part into cavity• Applications: large parts, typical of aerospace

industry


Figure 20.45 ‑ Explosive forming: (1) setup, (2) explosive is detonated, and

(3) shock wave forms part and plume escapes water surface


Electromagnetic FormingSheet metal is deformed by mechanical force of

an electromagnetic field induced in workpart by an energized coil

• Presently the most widely used HERF process• Applications: tubular parts


Figure 20.47 ‑ Electromagnetic forming: (1) setup in which coil is inserted

into tubular workpart surrounded by die; (2) formed part


Finite Element SimulationsPredict and minimize tearing and wrinkling locations

nsmwww.eng.ohio-state.edu

www.esi-group.com

tmku209.ctw.utwente.nl

SELESAITERIMA KASIH

Spinning:Makes “cups” from sheet metal,for lower production.(cold)

Roll forming (Hot):Moves bulk metal, makes I-beams

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Roll forming (Cold):Bends sheetmetal into complex cross-sections

Directional Properties in RollingOriented flowlines:- Less ductility when bent in one direction- More ductility when bent in the other

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Cold Rolling: Sheetmetal production

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www.nzsteel.co.nz finance.pipex.com


Cluster rolls support smaller contacting rolls

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www.elgiloy.com


Residual Stresses may lead to warping after bar is machined

Large reduction Small reduction

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Roll Forming of Sheetmetal (cold)

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www.cometroll.com www.safeair-dowco.com

Roll Forming of sheetmetal

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Blanking of Sheetmetal: Efficient Nesting of Blanks

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Sheetmetal: Bending

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Springback:

Sheetmetal: Minimum Bend Radius

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Tight radius bends (folds) require metal with ~40% ductility

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Bending of SheetmetalUse notches to avoid tearing and wrinkling in right-angle bends

Press Brakes:For lower production

volumes10-30 foot long50-3000 tons

Bending of Sheetmetal

www.loomismetals.com

Bending:Press-Brake Operations

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Deep Drawing (cold, for sheetmetal)- Punch draws blank into die- Metal is supported on both sides to avoid wrinkling- Hold-down pressure (blankholder force) is primary process variable if too high: tearing if too low: wrinkling

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www.endo-mfg.co.jp

Deep Drawing“Draw beads” may be used to control metal flow

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Cost comparison: manufacturing a round sheet-metal container by spinning and deep drawing. For small quantities, spinning is more economical.

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Progressive Stamping DiesCommon method to handle complex parts

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Tube-drawingDOM: Drawn Over Mandrel TubingSeamlessThin wall, tight tolerance, strong

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www.twmetals.com

Malicky

“Floating plug”

Bahan Kuliah Manufacturing Procces I University Of Lampung

Engineering

Transcript of Bahan Kuliah Manufacturing Procces I University Of Lampung