CAD-CAM SIMULATION OF CONTROL ROD and ...

Industrial Training Report 1

CAD-CAM SIMULATION OF CONTROL ROD

and

REJECTION ANALYSIS

Industrial Training Report

Submitted in partial fulfilment of the requirements of the degree of

BACHELOR OF TECHNOLOGY in

MECHANICAL ENGINEERING

by

B.R. STHAVISHTHA

13ME125

DEPARTMENT OF MECHANICAL ENGINEERING

NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA

SURATHKAL, MANGALORE - 575025

August 2016


COMPANY PROFILE

Auto CNC Machining Ltd. was constituted in 1988 by the promoters of M/s ACE

DESIGNERS Ltd., who are the pioneers and leaders in manufacturing CNC machines. Its

located in Peenya Industrial Area, Bangalore, India.

According to a market survey, there was a potential for outsourcing components in various

engineering and automotive industries. With this motive, Auto CNC established a

manufacturing unit with two CNC turning machines. Since then Auto CNC has a number of

Blue chip companies as customers and has grown in size and strength.

It comprises of Process Engineering and Development (PED), Management Information

System (MIS), Quality Control &Assurance Department and Packing & despatch

departments.

Quality Objectives of the company

Improvement of productivity

Enhance customer satisfaction

Training and retraining of employees

Quality Policy of the company

"We are committed to manufacture and supply of engineering components and assemblies

meeting customers' quality and delivery requirements by continually improving the

company's QMS with employee involvement."

Mechanical components in the industry

The shop floor machines include Vertical machining centre (VMC), Horizontal machining

centre (HMC), CNC turning machine, lathe, cylindrical grinding machine, surface grinding

machine, drilling machine, turn mill centre, water-jet machine, centering and facing machine,

bench grinding machine, manual milling machine, cutting machine and leak testing machine.

The mechanical components used in the metrology department include Coordinate measuring

machine (CMM), profile projector, crack testing machine, height gauge and hardness tester.

Overview of products manufactured

Automotive parts - lifting rod, pinion, link, universal joint, motor piston, valves and LDA

assembly.

Healthcare parts - tube mount plate and skan ray.

The healthcare parts machined find applications in X-ray machines, MRI scanners, baby

warmers etc.


Machine tool parts - cam gear, cam ring and tool holders of Vertical machining centres and

Horizontal machining centres.

Auto CNC presently serves Automotive sectors, Medical equipments sectors, Production of

machine tool parts and Earth moving equipment sectors.

General Process flow for a component in the Industry

Raw material procurement

Cutting operation

CNC turning operation

Milling operation

Tapping operation

Grinding operation

Surface treatment- blackening, electroplating, zinc plating, hardening and case

carburising

Final inspection

Pack and despatch

Raw material procurement, initial blank cutting operations and surface treatment are

outsourced to a vendor. Other operations are done in the company itself.

Turning operations are carried out on CNC turning centres. Milling operations are carried out

on VMC or manual milling machine. Tapping operations can be carried out on the turning

centres or on a hand tapping machine. Grinding operations are carried out on grinding

machines. Final inspection is carried out in the Quality Control Department. Packing and

despatch is done by the Packing and despatch department.

Outsourcing

Auto CNC chooses to outsource some of the processes that affect product conformity

requirements, such processes are controlled and results are monitored to ensure that the final

products meet the requirements. At present, the following processes are subcontracted:

Bar cutting

Surface treatment

Heat treatment

The above processes are verified against customer requirements and the company takes the

total responsibility.

Safety Practices adopted in the Organisation

The industry also adopts suitable safety practices of wearing safety shoes, hearing

equipments and proper dress codes.


OBJECTIVES

The objective of this industrial training performed was to interpret what I learnt from my

studies in terms of adopted industrial operations (including machine, material handling and

machining operations). The experience gained would give an exposure to the student to apply

the acquired knowledge "hands-on" in the working environment and would also make the

student experienced enough to select an optimal solution while handling a situation.

As an industrial trainee (or an intern), , I was given the task of completing two projects :

CAD/CAM Simulation of Control Rod and Rejection Analysis in the Process Engineering

and Development (PID) and Management Information System (MIS) Departments of the

industry respectively.

The objective of the project, CAD/CAM Simulation of Control Rod was to create a CAD

model, use the CAM software and then manufacture it. The objective of the second project,

Rejection Analysis was to perform a detailed study of the failed parts and provide effective

suggestions to tackle the situation and to investigate the reasons for defects.

To complete the above projects, I was supposed to initially visit the production section of the

industry to observe the mechanical components in the industry and understand the various

machining operations. I was also expected to read and understand the engineering drawings

and understand the working of different gauges used for measurement and their methods of

use in the shop floor.


WORK PERFORMED

1. CAD/CAM SIMULATION OF CONTROL ROD

Summary of the work performed

A CAD model of the control rod machined in the industry was created in Autodesk Fusion

360 (an integrated CAD-CAM software) with similar type of tools used and machining

parameters defined in the software. Finally, a CNC code was generated in the CAM section

which was directly input into the CNC machine, rather than manually typing the code by the

operator. The machining time estimated from the software was finally compared with the

actual machining time by the operator which may give some ideas to the operator how to

improve the machining time.

Detailed Description

The control rod ( a part which is used in earth moving machinery ) is initially a casted

product. It is sent to Auto CNC Machining Pvt. Ltd. for performing the machining operations.

The work holding device used in all the three setups is a fixture. The first two setups are

performed on a CNC horizontal machining centre ( Hyundai - KH50G ) in Auto CNC plant -

I. The third ( final ) machining operation is performed on a radial drilling machine (manually)

in Auto CNC plant -II.

Auto CNC Machining Pvt. Ltd. was assigned only the task of machining the component and

the inspection of the machined parameters. The raw material procurement , casting process

and the final operations would be done either by the customer company itself or outsourced.

Setup - I


Tools used and operations performed

Tool Insert Operation

Φ50 cutter SCMT 120408 PA120

SPL Milling insert

Face milling

Φ85 boring tool SCMT 120408 PA120

SPL Milling insert

Finish boring


SPL Milling insert

Rough boring

Φ94.8 boring tool SCMT 120408 PA120

SPL Milling insert

Rough boring

Φ40×90° chamfer tool TCMT 16T308- SM IC907 Chamfering


SPL Milling insert

Slotting

Φ93 boring tool TCMT 16T308- SM IC907 Back facing

Φ29 × 45° chamfer tool TCMT 16T308- SM IC907 Back chamfering

Φ95 micro-boring tool TPGX 090204L Finish boring

Simulations of operations in Autodesk Fusion 360

1.Face milling using φ63 face mill cutter 2. Rough boring using φ88 rough boring tool

3. Rough boring using φ94.5 boring tool 4. Rough boring using φ85 boring tool


5. Chamfering using chamfering tool 6. Slot roughing using φ106 boring tool

7. Back facing using φ93 back facing tool 8. Back chamfering using φ38 end mill

9. Semi-finish boring using φ94.8 boring tool 10. Finish boring using φ100 micro-boring tool

Machining time of each operation

Serial number of

Operations

performed

Machining time

Serial number

of Operations

performed

Machining time

1. 4 minutes 50

seconds 6. 7minutes 50 seconds

2. 9 minutes 11

seconds 7. 2 minutes 24 seconds


3. 2 minutes 1seconds 8. 4 minutes 5 seconds

4. 5 minutes 51

seconds 9. 8 minutes 58 seconds

5. 1 hour 9 minutes 22

seconds

Total machining time for setup-I : 1 hour 52 minutes 6 seconds

Setup - II



φ23 U drill TCF070304 CCU34

And

TCF070306 CPV34

Drilling

φ24 drill HSS Drilling

φ8 drill HSS Drilling

φ8.5 drill HSS Drilling

φ20 end mill Carbide Hole interpolation

1/8-28 BSPT tap HSS Tapping

Simulations of operations in Autodesk Fusion 360

1. Drilling using φ23 HSS drill 2. Drilling using φ24 HSS drill


3. Drilling using φ8 long HSS drill 4. Drilling using φ8.5 HSS drill

5. Hole milling using φ20 end mill 6. Tapping using 1/8 -28 BSPT Tap

Serial number of

Operations

performed

Machining time

Serial number

of Operations

performed

Machining time

1. 55 seconds 4. 47 seconds

2. 2 minutes 31 seconds 5. 4 minutes 41 seconds

3. 2 minutes 47 seconds 6. 31 seconds

Total machining time of setup-II : 11 minutes 29 seconds

Setup-III

This is done on a radially drilling machine which is manually controlled. Hence this

operation need not be simulated in the CAD-CAM software. The machining time in this case

depends upon the operator and other conditions.



φ8.5 HSS Drill - Drilling

φ25 carbide drill - Drilling

1/8-28 Tap - Tapping


Machining time estimated from software: 2 hours 3 minutes 32 seconds

Practical machining time: around 3 hours

The difference arises due to different number of machining passes, cooling time, placing and

removing the work piece from the machining place etc.

Conclusions

CAD-CAM simulation of a part before being actually manufactured gives an idea to the

operator about the collisions of the tools with the fixtures and other components present in

the machining zone. It also helps in generating a CNC code for profiles of complicated

geometry.

The machining time ( cycle time) calculated from the software may be different from the

actual scenario as it depends upon the number of passes, tool geometry, operator, pallet

change time etc.

2. REJECTION ANALYSIS

For this work , graphs were plotted based on cost trend, ppm count and pareto analysis of

rejected parts to perform a detailed study of the failed parts.

Rejection analysis based on PPM count

Here, PPM count indicates the ratio of number of rejected parts to accepted parts in parts per

million.

Figure . Rejection analysis for 2012

0 2 4 6 8 10 12 140

2000

4000

6000

internal rejection analysis

cumulative ppm count

ppm count

target

0 2 4 6 8 10 12 140

2000

4000

6000

external rejection analysis


ppm count

target


Figure . Rejection analysis for 2013

Discussions on Internal rejection analysis(based on products to be delivered to customers)

PPM count in May 2013 is too high. From the day wise rejections, the top 3

components with maximum number of rejections are:

209 rejected pieces of control shaft because of corrosion in the shaft.

54 rejected pieces of pivot bearing because of a taper formed on the bore.

30 rejected pieces of link because of the presence of oversize groove and

formation of taper in the bore.

PPM count in November 2013 is above the target limit.From the day wise rejections,

the top 4 components with maximum number of rejections are:

9 rejected pieces of bracket because of missing operations and damage

observations.

4 rejected pieces of washer because of damage observed on edges.

3 rejected pieces of upper plate because of damage in chamfer and melting of

side edges.

3 rejected pieces of pork pivot insert because of wrong butting.

External rejection analysis (based on raw materials procured from customer companies)

The plot shows that the PPM count in september 2013 is too high above the target limit. The

reason for a large number of rejections is available with the customer company.

0 2 4 6 8 10 12 140

2000

4000

6000

internal rejection analysis


ppm count

target

0 2 4 6 8 10 12 140

1

2

3x 10

4 external rejection analysis


ppm count

target


Rejection analysis based on cost trend

Quality cost trend for 2012 from January 2012-January 2013

Quality cost trend for 2013 from January 2013 to January 2014

Internal rejection cost

The internal rejection cost is very high in the month of May 2013. From the day wise

rejections, the maximum cost of rejections are:

Rs. 53495.6 for Pivot bearing because of a taper observed on the core.

Rs.24110.2 for control shaft because of corrosion observed on the shaft.

External rejection cost

The external rejection cost is very high in the month of September 2013. From the day

wise rejections, the maximum cost of rejections are:

Rs. 5600 for Side protection because the total length and side mill were

undersize.

Rs.1041 for Plate clamp because of a step observed on the outer diameter.

The external rejection cost is above the target limit for the month of February

2013.From the day wise rejections, the maximum cost of rejects are:

Rs. 4050 for X Ray shield top because the bore diameter was oblonged.

0 2 4 6 8 10 12 140

1

2

3x 10

5 internal and external rejection cost trend

internal rejection cost

external rejection cost

target

0 2 4 6 8 10 12 140

1000

2000

3000

rework cost trend

rework cost

target

0 2 4 6 8 10 12 140

5

10x 10

4 internal and external rejection cost trend

internal rejection cost

external rejection cost

target

0 2 4 6 8 10 12 140

1000

2000

3000

4000

rework cost trend

rework cost

target


Rs. 960 for cup and hub because of the formation of bend and drill oblong.

There could also be other reasons other than the one mentioned above for external rejections.

Pareto analysis based on the number of scrap parts

According to "Pareto Principle",in any group of things that contribute to a common effect, a

relatively few contributors account for the majority of the effect. A Pareto diagram is a type

of bar chart in which the various factors that contribute to the overall effect are arranged in

order according to the magnitude of effect. This ordering helps in identifying a ''vital few'' out

of ''useful many''.Pareto principle is also known as 80/20 rule because 80% of its problems

may be caused by 20% of causes.

January 2015

From the above graph, it is quite obvious that link,universal joint and cam ring should be

given utmost attention based on 80/20 rule.

Defect Causes

180° angle shifted in cam ring Problem in CAM program

Damage of cam ring Ejection of component while running

Oversize and undersize of outer diameter of

link

Insert broken

Step observed on rib thickness Due to drawbar problem, spindle got

declamped.

number

of scrap

parts

cumulative

percentage


June 2015

From the above graph, it is quite obvious that universal joint and link should be given utmost

attention based on 80/20 rule.

Defects Causes

Dent mark on grinding face of link Improper grinding

Hole finish poor and hole oversize of link Insert wear

Shifting of bore and wall thickness problem

in universal joint

Improper setting

Bore undersize in universal joint Problem in previous operation

Conclusions

Minimising the rejection costs and the number of scrap parts are important factors in ensuring

good quality products. Since the importance of a manufacturig industry is very high,

manufacturing good quality products is essential to sustain in the global market. Good quality

results in good establishment of brand name and gains reputation in the market. Thus an

effective way to analyse the causes and solutions is necessary to improve and save the overal

quality of the product, based on the graphs plottted.

Future works can be done on classifying the defects of a product and making a pareto

analysis of the defects. This can provide sufficient information to the organisation in taking

corrective actions.

Other works in the industry during the training/internship

I also observed the working of main mechanical components in the industry(including

workshop and metrology lab) - LDA Assembly machine, Centre lathe, Centering and Facing

machine, Slip gauges, Column drilling machine, Profile Projector, Coordinate measuring

machine, Dial Calibration Tester, Floating carriage micrometer and Vernier calliper checker.

cumulative

percentage number

of scrap

parts


SUMMARY

With a rare opportunity to observe the working of modern CNC machines(of almost all

kinds),this industrial training (or internship) seemed extremely useful for my career in that

aspect. It helped me in recollecting the fundamentals I had learnt in my theory classes in the

field of Manufacturing. Interaction with the operators about the product, alternative

machining operations and the usage of gauges also enhanced my communication skills in

addition to my technical knowledge. Working on the instruments used in quality assurance

department, metrology labs helped me to work on things which are absent in the labs of our

institute. Apart from the technical knowledge gained, I also understood the sequence of work

flow between each department and the respective work performed in each department of the

industry. Completion of the projects helped me in learning new concepts which had never

been learnt in classes earlier.

I am thankful to the Department of Mechanical Engineering for making the industrial training

as a mandatory part of the curriculum. I am also deeply grateful to the workforce of Auto

CNC Machining Ltd. for assisting me with the projects and training activities.

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