PROJECT REPORT

ON

PRESSING & WELDING

TECHNOLOGY

AT

CAPARO MARUTI LTD.

GURGAON

(15thJune to 30thJuly,2014)

SUBMITTED BY :---- MRINAL RATHORE B.E. 3rd year, MECHANICAL IMS ENGINEERING COLLEGE

ACKNOWLEDGEMENT

Industrial training is an indispensable part of our engineering curriculum. It provides the students an opportunity to gain experience on the pragmatic applications of their knowledge. My training at Caparo Maruti Ltd, Gurgaon has been very fruitful. I am sure that the experience I gained here will help me towards making me a competent and proficient engineer.

I would like to convey my sincere gratitude to MR.VIRENDER SINGH ,who entrusted me with the responsible project work and provided me with timely and proper guidance whenever required. This enabled me to gain experience in not only the technical and practical aspects of industry but also in human relations, teamwork and also provided great insights into the actual working of an industry. Without his efforts this training would not have been as great learning experience as it been.

I would also like to thank MR. RATAN YADAV (AGM, HR), who ensured a proper work environment.

I take this opportunity to thank my training incharge MR.UMESH KUMAR and my H.O.D MR.KULDEEP SINGH for their constant advice.

I hereby also declare that the contents in this report are true to the best of my knowledge.

TABLE OF CONTENTS

S.NO. TOPIC1 Introduction

2 Company profile

Welding shop

3. Resistance welding

3.1 Spot welding

3.2 Projection welding

3.3 Seam welding

4. Arc welding

4.1 Stud welding

5 Metal inert gas welding

5.1 CO2 MIG welding

6. Equipments for welding

6.1 IT GUN

7. Welding shop specifications

Press shop

8 Operations in press shop

9. Project assigned

10. Learning

INTRODUCTION

Caparo Maruti Limited is a joint venture of Maruti Udyog Limited. Caparo group belongs to Lord Swaraj Paul. It is a U.K based company. It has 19 plants all over India , amongst them 3 are the joint ventures with Maruti Udyog Limited.

Caparo maruti is a medium scale industry. It consists of 400 employees in Gurgaon plant. It makes 21sub components out of which 7 are made only at press shop and remaining by the help of welding process. There are 2 shops in this plant -a. PRESS SHOPb. WELD SHOP

In press shop there are 4 mechanical presses (800T, 400T, 400T,400T) and one hydraulic press.

The processes involved in this shop are -a. Drawingb. Trimmingc. Piercingd. Side bending

In weld shop there are 4 welding processes involved –

a. Spot welding (using IT Gun)b. Projection weldingc. Stud weldingd. MIG welding

COMPANY PROFILE

A. WELDING

It is a fabrication technique and is used to join the metals by heating and then pressing together.

FIG . 1

Welding is of various types:-

1. Resistance welding

a. Spot welding b. Seam welding

2. Electric arc welding

3. Gas welding

In Caparo Maruti Limited (CML) there are different types of welding techniques used for processing of sub assemblies of the automobiles like-

1. Spot welding2. Projection welding

Welding is the process of joining metals

HEAT JOININGOF METAL

MELTINGOF METAL

FILLER MATERIAL

NO FILLER MATERIAL1. CURRENT2 GAS3 CHEMICAL REACTION

3. Stud welding4. MIG (metal inert gas welding) welding

FIG. 2

1. RESISTANCE WELDING

It is the process of joining metal pieces together by raising the temperature of the pieces to fusion point and applying a mechanical pressure to join them. In this, the pieces to be joined are held together and a strong electric current of high amperage and low voltage is passed through them. This current comes across a certain resistance in passing from one piece to other and it is this resistance offered to the flow of current which results in raising the temperature of the two pieces to fusion or melting point at their junction. The mechanical pressure applied at this moment completes the weld.

FIG. 3

Resistance welding process depends upon correct application and proper control of the following factors:-

1. Welding current – Enough current is needed to bring the metal to its plastic state for welding.

2. Welding pressure - In this welding mechanical pressure is required to be applied at two stages- first to hold the metal pieces tightly between the electrodes, while the current flows through them, and secondly when the metal has been heated to its plastic state, to forge or squeeze the metal pieces together to form the weld. The former is known as WELD PRESSURE and the latter FORGE PRESSURE

3. Heat is directly proportional to the square of current and time.

H=I2xRxT. H = HeatI2 = Current in amperes, R = Resistance of the work in 0hms, T = Time the current flow in cycles ( 50 CYCLES IN ONE SECOND)

4. Time of application - It can also be described as cycle time and is the sum total of the following time periods-

a. Weld time – It is the time period during which the current flows through the metal pieces to raise their temperature.

b. Squeeze time or forging time- It is the time period during which the forge pressure is applied to the metal pieces to squeeze them together to form the weld.

c. Hold time- It is the time period during which the metal pieces are held together under forge pressure for a short while to enable the weld to solidify. It can therefore, be called cooling time also.

d. Off-time- After cooling of weld the electrode pressure is released and the metal pieces removed for the next operation cycle. The time period between this release of electrodes and the start of next welding cycle is called off-time.

5. Contact area of electrodes - The weld size depends on the contact area of the face of the electrodes. It can be varied by selecting suitable set of electrodes to provide the desired area of contact at their tips.

FIG.4 WELD TIME CONTROL FOR SPOT WELDING

TIMES Q U EE

ZEUP

SLO

PE WE

LD

DN

SL

OPE

HO

LD O

FF

CU

RR

EN

T

NUGGET TEST (RELATION BETWEEN CURRENT AND PRESSURE) -

FIG. 5

Current

Pr es su re

A:High Current and High Pressure - SPLASHB:Medium current and medium Pressure - GOOD WELDC: Small Current and High PressureNO NUGGET

ExplosionSmall

Large

Nugget Dia(Strength)

No NuggetSplash

Good W

eldB - will have Good WeldLess SpattersOptimum Nugget Dia

1 (a). RESISTANCE SPOT WELDING

The principle of spot welding- in which a transformer core is having primary and secondary winding. One end of the secondary winding is connected to the upper electrode carried in the movable copper or bronze arm A and the other end to the lower electrode mounted on the fixed arm B. In operation the metal sheets S1 and S2 are held and pressed between the electrodes and a strong current at low voltage is switched on. Due to the resistance offered by the sheet metal to the flow of this current the temperature at the contact surfaces rises to fusion point and the weld is completed under the contact pressure of the electrodes.

WELD SPOTS

CHIESEL

NUGGET CHECKING METHODIF METAL SOUND ----- OK

NUGGET DIA

U T M

TENSILE STRENGTH CHECKING METHOD

SPOT SHOULD NOT FAIL

FIG.6 SPOT CHECKING METHOD

SPOT WELDING ELECTRODES & ELECTRODE HOLDER

The electrode holders should possess the following characteristics-1. They should be good conductors of electricity.2. They should be good conductors of heat.3. They should possess high mechanical strength and hardness.

Most of these holders are water cooled and so are the electrode tips which are made hollow for this purpose.

1(b). RESISTANCE PROJECTION WELDING

This process is similar to spot welding but differs from the latter in that the spots at which the welding takes place are previously located by providing projections at the desired locations on the surface of one of the work pieces. Thus the surfaces of the work pieces are in contact with each other only at the projections. As the current is switched on the projections are melted and the work piece pressed together to complete the weld, by pressing the upper electrodes downwards

FIG. 7 PROJECTION NUT WELDING

UPPER ELECTRODE

PIN

LOWER ELECTRODE

SPRING

OKNG

NUGGET

PIN

1(c). STUD WELDING

It is an arc welding process adopted specifically for welding of studs to structures and other surfaces for fastening other components to them .it is done with the help of a specially designed gun called stud welding gun. As soon as the gun trigger is pressed the current is switched on and a solenoid inside pulls the stud away from work piece by a predetermined distance. This creates an arc between the stud and the work and the stud end and base metal melts. It has a controller, 3 phase transformer, and automatic trigger.

DRAWBACK-

If get unbalanced very difficult to balance.

FIG. 8

STUD WELDING (FLASH WELDING)

FIG. 9

LIFT PLUNGE

LIFTING ACTION

WELDING CURRENT

HEATING TEMPERATURE

STUD

BASE METAL

EXCITATION OF COIL

LIFTED CONDITION

PILOT ARC VOLTAGE PILOT ARC

WELDING PULSE

PLUNGE POINT

MELT CONDITION

1(d). MULTI SPOT WELDING (MSW) -

It is similar to spot welding but as the name suggests it is used for doing multiple spots at the same time. There are number of cylinders having magnetic slips in them which creates magnetic field.

Reference condition for Stud welding

M3 0.6-1.2 4.5 60-90 15-25

M4 0.6-1.2 5.5 70-100 15-25

M5 0.6-1.2 6.5 90-130 15-25

M6 0.6-1.2 7.5 130-170 18-30

M8 0.6-1.2 9.5 180-240 18-30

DIA OF STUD TO BE

WELDED

STUD SIZE

SHEET THICKNESS

CHARGING VOLTAGE

STRENGTH OF SPRING mm

REMARKS

SET STICK OUT TO 2 ~ 2.5 MM IN ALL CASE

SET LIFT 1 ~ 1.5 MM

SET CURRENTAND TIME FOR PILOT ARC MOST SUITED

A 5030

200 400M.S.

15

100

SPRING FORCE

FIG. 10

1(e). PORTABLE SPOT WELDING (PSW)- It is a non integral type welding. It consists of a kick less and a coaxial cable. The nugget produced is of very high diameter. The cost production is less because it uses only 1 IT gun in place of 2.

FIG. 11

2. GUN WELDING

The specific use of this method is in welding of irregular surfaces, such as fabrication of automobile bodies. The electrodes are actuated either hydraulically or pneumatically. The equipment consists of a transformer, flexible leads connecting the transformer to the welding gun, the welding gun unit comprises of two electrodes and a trigger switch.

Welding gun Transformer Controller ELCB

PSW WELDING SYSTEM

2(a). IT GUN (inbuilt transformer gun)

There are 4 cables in this gun-

1. Power cable (red)2. Air cable (green)3. Water cooling cables (black)

FIG.12

The water is coming from cooling towers with a flow rate of 6 to 8 liters/ minute. The force produced by trigger is 200kg. The major components of gun are-

1. firing card2. control card3. trigger switch4. transformer5. thyristor6. primary and secondary windings7. electrode8. arms

DISADVANTAGES

1. Gun weight is very heavy. 2. Carbon deposition is there which creates insulation. It is removed

by filing and cooling. 3. Machine breakdown due to movable arms. 4. Production is slow. 5. Requirement is of 27 deg Celsius is there but the temperature is 45

deg Celsius in the plant.

3. METAL INERT GAS WELDING (MIG)

MIG stands for metal inert gas welding. It involves welding of metals using consumable metal electrode in an inert gas atmosphere. The arc is struck between the electrodes and the work piece. The electrode is in the form of continuous wire which is fed into the arc, by an adjustable speed electric motor, at the same speed at which it is melted and deposited in the weld. The electrode holder also incorporates passage for supply of inert gas for shielding the electrode, molten weld metal, arc from atmospheric contamination. Usually D.C. with reverse polarity is used in MIG welding. Use of this enables a deeper penetration.

3(a). CO2 MIG WELDING

In this process the electrode used is either flux cored or magnetized flux coated. Co2 is used as a shielding gas. In either case the filler wire or electrode is fed the arc in the same way as in MIG welding.

In Caparo Maruti Limited (CML) there are different types of welding techniques used for processing of sub assemblies of the automobiles like-

1.Spot welding 2.Projection welding 3.Stud welding 4. MIG (metal inert gas welding) welding

WELDING SHOP SPECIFICATIONS-

Area 1728 m2 Welding jigs 72 no. Number of Guns 110 Manpower 128/shift Operation shift 2

PRESS SHOP

Press is a machine which undergoes various processes by applying tonnage on the raw material.

There are various types of presses-1. hydraulic presses2. mechanical presses3. pneumatic presses

In CML there are 4 mechanical presses (800T, 400T, 400T, 400T) and 1 hydraulic press.

The raw material used in press shop is cold rolled forged steel sheet (because CRS has high tensile strength, elongation is good) as per requirement.

The companies which supply raw material are TATA, BHUSHAN, and POSCO STEELS.

The following operations which are held in the press shop are -

1. Blanking – It is the process in which the punch removes a portion of material from a stock which is a strip of sheet metal of the necessary thickness and width. The removed portion is called a blank.

2. Drawing – It is the process of making cups, shells, and similar articles from metal blanks.

3. Trimming - It is the process of removing extra material.

4. Piercing- The process of making holes in sheet.

5. Reforming and piercing - It is the process of providing holes, punches to the part.

6. Side bending- It is a operation of deforming of a flat sheet around a straight axis where the neutral plane ( plane with no stresses) lies.

FIG.13

.

FIG. 14

FIG. 15

HYDRAULIC PRESS

FIG. 16

PROCESS CHART-

RESTRIKING OPERATION

BENDING & PIERCING

OPERATIONTO CUSTOMERDRAWING

OPERATION

PRESS PROCESS FLOWPRESS PROCESS FLOW

FILTER2Flange Gap Detection

IMPROVED QUALITY PRODUCT TO CUSTOMER

FILTER 1Wrinkle Prevention

TRIMMING OPERATION

FIG.17

Specifications

Area 1648 m2Number of presses 4Press capacity 800T -1 press

400T – 3 presses

Manpower 32/shiftOperational shift 32 types of lines tandem lines Transverse lines

800 T press - motor of 96 kW 3.3- 3.2 bar atm. Pressure with die 2.8 bar atm. Pressure without die400T press- motor of 64 kw 2.8 bar with die 2.5 bar without die Hydraulic clutch is used

Components of dies-

1. Upper die2. Lower die3. Blank holder

SPECIFICATIONS OF DIES

Number of dies – 114 diesWeight of die - 20 tonDie raw material F/C 25Cushion pressure -0.9-1.2kg/cm2

Main Cause CountermeasureSpot placement shifted to radius / gap Electrode Guides provided on jig.

Spot is closed to sheet gap. Electrode Guides provided on jig.

Spot placement shifted to radius of hidden child part.

Electrode Guides provided on jig.

Gun Access difficult, leading to inclined position.

Provide copper pad to increased access area for electrode.

DEFECT - SPOT DENT / HOLE

QUALITY IMPROVEMENT

What is Quality?: Definitions and Contrasts

The term quality means different things to different people. For example, a quality automobile may be one which has no defects and works exactly as we expect. "Quality is fitness for use." However, there are other definitions widely discussed. Quality as "conformance to specifications" is a position that people in the manufacturing industry often promote. Which include the expectation that a product or service exceed the expectations of the customer? 1) Meet customer standards, 2) meet and fulfill customer needs, 3) meet customer expectations, and 4) will meet unanticipated future needs and aspirations. Still others simply ignore definitions and say "I'll know quality when I see it." It seems that we all 'know' or 'feel' somehow what quality is. A product or service that exceeds our preconceived idea about the quality of the product or service to be received is likely to be designated as a quality product or service. It is equally clear that the best of a group of bad products is not likely to be perceived as a quality product

Definition of Quality:

1. Customer-Based Fitness for use, meeting customer expectations.

2. Manufacturing- Based

Conforming to design, specifications or requirements,Having no defects.

3. Product-Based The product has something that other similar productsDoes not that add value?

4. Value-Based The product is the best combination of price andFeatures.

The Terminology of Quality

TERM DEFINITIONS

Customer Satisfaction 'Just what the term says...'

Quality Tools Tools used to measure and observe every aspect of the creation of a product.

Metrics Ways to measure: for example, time, cost, customer satisfaction, quality.

Flow Charting Creating a 'map' of the operations of a process.

Benchmarking Comparing your product to the best competitors.

Adding Value Adding something that was not there before that the customer wants.

'Bring to the Table'Refers to what each individual in a meeting can contribute to a meeting, for example, a design or brainstorming meetings.

QUALITY DEFECTS:

1. PRESS SHOP.

A. Cracks.B. Neck.C. Wrinkles.D. Dents.E. Burs.

2. WELD SHOP.

A. Failure of spot by spot welding.B. Nugget test failure.

QUALITY DEFECT ANALYSIS-

1 TOOLS: There are 7 QC tools are as given below: 1). Fish-bone analyses. 2). Pareto diagram. 3). Histogram. 4). Check sheets. 5). Control chart. 6). Flow chart. 7). Scatter diagram.

3 PREVENTIVE MEASUREMENT :

a) FMEA (Failure mode & effective analysis)

b) MSA (Measurement system analysis)

c) Control plans

d) 7 QC tools

Strategy to Change

DEMING APPROACH

3838

Deming ApproachDeming Approach

Dr.Deming

LEARNING

The training at CAPARO MARUTI LIMITED provides me with great knowledge in the fields of PRESS shop & WELD shop. I have seen the manufacturing of different parts of automobiles like DASH ALTO, DASH WAGONR etc. using mechanical presses of various tonnage where 4 operations take place on a cold rolled forged steel sheet –

1. Blanking2. Drawing3. Trimming & piercing4. Side bending

I have learnt welding concepts for different welding processes –

1. Spot welding2. Stud welding3. MIG welding4. Projection welding

THANK YOU!!!