SPATTER REDUCTION

Project by : Prateek BiswasSummer Trainee MSIL, WBMS

July 2013

Introduction of Plant

Weld Shop B Plant is the second weld shop of Maruti Suzuki India Limited (MSIL) in Manesar Plant. This is the fifth plant in MSIL overall including Gurgaon Plants.

The model which is manufactured over here is Swift (YP8). The plant was set up to produce two models namely Swift (YP8) and Ritz (YV4) with a planned capacity of 2,50000 bodies per, but due to ever increasing market demand of Swift, WSMB worked hard to increase the YP8 capacity from 1,60,000 to 2,50,000. A lot of automations were carried out to improve the capacity.

Weld Shop B has 100% automation.

Department Policy1. Raising the level of employee morale to meet the challenge ahead by: Providing safe and healthy working environment by raising the level of 5S to next level. Good communication by one to one interaction. Focus on skill improvement by imparting internal training for safety, quality, and productivity. 2. Increasing capacity and productivity by: Preventive and predictive maintenance of jigs and robots. Improving efficiency 3. Improve customer satisfaction by continual improvement in quality through:Proactive approach for prevention of defect. & System adherence 4. Reduction of cost through localization and wastage reduction. Safety First – No accidents/ incidents on the shop floorQuality Number 1 - Customer Number #1High Productivity – Fulfill market demand on timeLow Cost – Minimum cost

Layout of Weld Shop B - Manesar

OverviewFollowing Model is manufactured in Weld Shop Manesar B -

YP8 (Swift) : Lxi, Vxi, Zxi ; Ldi, Vdi, Zdi The body panels produced in the press shop and the other small components (supplied by the vendors) are joined here to give the “white body” or “shell”. In a typical car body, total 2684 welds are done. The weld shops have the following facilities.

• Welding jigs• Portable Spot welding guns• Spot Welding robots• CO2 Welding robots• Hemming machines• Sealer Application units• Number Punching machines

Division of Weld Shop B1. UNDER BODY: Here different underbody panels are welded together. These comprises of rear underbody, central underbody, front engine room panel. These underbody panels are prepared on sub line starting from singular components. The sub lines have specific jigs for each. There are chain hosts for transferring the jobs from one jig to another on sub lines. Finally these underbodies are put on the conveyor and welded together to give the underbody. The chassis no. is punched on the cowl top and it is welded to the front engine room panel.

Division of Weld Shop B2. MAIN BODY: As the body moves on the conveyor, roof and side body panels are welded to it to give the main body. The side body panels are prepared on the sub lines. Each side body consists of an inner side body and an outer side body. All the spots are welded onto the inner side body which is welded onto the outer side body.

Division of Weld Shop B3. WHITE BODY: The White Body line is common for both line-1 and line-2. The doors, hood and back door are attached onto the main body with the help of bolts and screws to make it a “white body”. The body is checked for dents, burr and spatter and these defects are repaired. After inspection and repairs the body is called WBOK. It is sent to the paint shop thereafter.

Welding Techniques used in Weld Shop B

For welding purpose, the following welding techniques are used in the Weld shop:

• Resistance welding.• MIG welding.• Gas welding.• Precision welding.

Resistence WeldingResistance welding basically consists of spot welding. In this process, an electric current flows through a resistive circuit to generate enough heat between two pieces of sheet metal so that the metal reaches molten stage .The resistance to the flow of current is provided by the work piece. The maximum heat is generated at the point of maximum resistance. * Weld Current* Weld Time* Pressure* Electrode Press Heat Generated is given by:H=I2xRxT. H = Heat.I2 = Current in amperes.R = Resistance of the work in ohms.T = Time the current flow in cycles.

Equipment used for Spot WeldingType of gun Definition Advantages Disadvantagesa) PSW - Portable spot welding gun

These are the conventional type and consist of transformer, timer, kick less cable, sub-cable etc

Light in weight, easy handling. a) High in Maintenanceb) Energy losses are high.c) Consumable cost high

b) IT Guns (Integrated Transformer)

IT gun (Integrated transformer) - Transformer and timer forms an integral part of the weld gun and welding parameters are controlled by the Microprocessor.

A) Energy losses are one third of PSW.B) Low maintenance.C) High spot quality and consistencyD) safe

a) Heavy in weight.b) Handling not easy compared to PSW

c) SSW (static spot welding gun).

Such gun are static and stand on one place and work like PSW.

Instead of gun, component is handled. So easy working.

Set up is robust. So no movement. Can work only on one place.

d) Servo Gun Such gun uses servo motor power in place of Pneumatic power for gun arm movement. Installed basically in robots.

a) Energy losses low. b) Low maintenance.c) High spot quality and consistency.d) safe.e) No Pneumatic power, so better tip force control.

Heavy in weight. Electricity consumption relatively high compared to Pneumatic IT guns.

MIG WELDING

This is a modern Arc welding technique which uses an inert gas atmosphere in place of flux and has auto feeding. This technique is used specially, for welding of thin sheets. In sheet metal work, this technique is extensively used. Inert gases like Argon are mainly used. CO2 gas is relatively cheap to Argon and has similar inert property. So in mass production, where finishing quality is not much required, CO2 gas is used in place of Argon. That’s why, the MIG welding which uses CO2 gas for inert atmosphere is called CO2 Welding.

Parameters of CO2 welding -

• Voltage : 16-24 V • Current : 60-100 A • CO2 Flow Rate : 16-20 Lt/min

Gas Welding

BRAZING:Brazing is defined as a joining process wherein coalescence is produce by heating to a suitable temperature and by using a filler metal having a melting point above 427oC and below the melting point of base metal.This is a non fusion process in which a dissimilar filler material fills the gap between close fitted surfaces of joining parts through capillary rise. SOLDERING:It’s also a joining process similar to Brazing, but with a difference in temperature.Soldering is done below the 427oC.This joining process is suitable for low application of heat.Example - Body outer skin is very sensitive to heat. So any repairs like dent etc are repaired by soldering.

Precision Welding

The stud welding is being done in Weld Shop, through precision welding.

The welding instruments consist of controller, feeder, cable, feed pipe, gun etc.

Project Contents

• What is Spatter?

• Need and scope of Spatter Reduction

• Reasons for Spatter

• Effects of Spatter

• Flowchart of procedure

• Activities done for Spatter Reduction

• Results achieved AFTER Spatter Reduction

• Learning

What is Spatter?

The small particles of molten metallic material that are expelled during spot welding, are called spatter.

Need and Scope of Spatter Reduction Project

• Currently weld spatter is a major concern as per 1. Safety : Injuries to workers handling weld robots2. Cost and Quality standards : Spatter sticking to work

pieces and tooling3. Cost standards : Loss of material

• High spatter percentage currently.• Moving towards full automation in welding processes is

good scope for significant spatter reduction.

Reasons for Spatter

1. Dust & contamination in sheet metal parts

2. Gap between work piece, electrode & work piece

3. Tip angle not perpendicular to surface of work piece

4. Improper Tip dressing

5. Tip mismatch

6. Parameters including current, pressure & cycle time are set

higher than required.

1. Dust and Contamination in Sheet Metal Parts

Rust Dust

2. Gap between work piece

Gap b/w sheets Gap b/w tips

Movable tip

Fix tip

Gap

3. Tip angle not perpendicular to surface of work piece

Non- Perpendicular

4. Improper Tip dressing

Tip wear from one side only

Improper gun angle

Tip Dresser

5. Shank Misalignment

Effects of Spatter

Safety Loss

Quality Loss

Production Loss

Poor 5-S

Effects of Spatter1. Safety Loss:

1. Can harm/burn skin

3. Burns clothes

4. Damages belongings

2. Spatter particles can cause Eye Injuries ( Safety goggles mandatory)

Effects of Spatter2. Quality Loss:

1. Spatter particles clog the jig miller, block & deform the body structure and decrease body accuracy.

2. Spatter particles on Clamp lead to Improper Clamping of body.

3. Spot Undulation on Body.

4. Spot Puncture on Body.

Effects of Spatter3. Production Loss:

1. Welding jigs – Spatter particles clog on the cylinders & clamps and blocks their functioning.

2. Jams Shuttle and NC Locator movement

3. Damages wires, cables and sensors

4. Clogging of spatter on PLS, Reed switch obstructs their signal visibility.

Spatter clog at jigs Spatter clog on wires

3. Production Loss:

Effects of Spatter4. Poor 5-S:

1. Spatter particles all over the floor.

2. Damages safety fence

3. Damages floor

Flowchart of Procedure

Identification of spots/Robots with spatter

Schedule number of spots with spatter

Data collection for spatter

Check for Spot with

Spatter

Result compilationOk

Shank matching correction

Check and correct Dressing position

Check and correct Spot position

Check and correct Sheet gap

Not ok

Spatter Monitoring Sheet

YP8 - HB - MB - SPATTER STATUSMODEL :YP8-HB-MB   DATE : Aug-2013

S N STN ROBOTSCHEDULE TOT. NO OF

SPOTS

SPOTS WITH SPATTER SPATTER PERCENTAGE  

Apr-13 Aug-13 Apr-13 Aug-13 REMARKS1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

1

6020

602 F 1 2 3 5 6 7 8 9 10                                 9 1 1 11 11  

2 602 G 1 2 3 5 6 7 8 9 10                                 9 2 2 22 22  

3 602 K 10 11 1 2 4 5 6 8 9 12                               10 2 2 20 20  

4 602 L 10 11 1 2 4 5 6 7 8 9 12                             11 2 2 18 18  

5 602 O 1 2 4 5 6                                         5 0 0 0 0  

6 602 P 1 2 4 5 6                                         5 3 3 60 60  

7

6030

603 Q 1 2 3 4 5 6 7 8 9 10 15 11 12 13 14                     15 5 5 33 33  

8 603 R 1 2 3 4 5 6 7 8 9 10 15 11 12 13 14                     15 5 5 33 33  

9 603 S 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16                   16 3 3 19 19  

10 603 T 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16                   16 4 0 25 0  

11 603 U 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 3 0 19 0  

12 603 V 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 3 0 19 0  

13

6040

604 W 1 2 3 4 5 6 7 8 15 9 10 11 12 13 14 15 1 1 7 7  

14 604 X 1 2 3 4 5 6 7 8 15 9 10 11 12 13 14 15 16   17 3 0 18 0  

15 604 Y 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18   18 1 0 6 0  

16 604 Z 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18   18 3 0 17 0  

17 604 AA 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18   18 0 0 0 0  

18 604 AB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18   18 1 0 6 0  

19

6050

605 AC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17   17 1 0 6 0  

20 605 AD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17   17 1 0 6 0  

21 605 AE 1 2 3 4 5 6 7 8 9 10 11 12 13 16 17 14 15   17 1 9 6 53 More gap b/w 2 sheets

22 605 AF 1 2 3 4 5 6 7 8 9 10 16 17 11 12 15 16 17 18 19 14 2 10 14 71 More gap b/w 2 sheets

23

6060

606 AH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 2 1 13 7  

24 606 AI 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 2 1 13 7  

25 606 AJ 1 2 3 4 5 6 7 8 9 10 11 12 12 2 2 17 17  

26 606 AK 1 2 3 4 5 6 7 8 9 10 11 12 12 2 0 17 0  

27

6070

607 AL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 1 1 6 6  

28 607 AM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 4 1 25 6  

29 607 AN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 1 1 6 6  

30 607 AO 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 1 0 6 0  

31

6090

609 AT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 3 2 17 11  

32 609 AU 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 1 1 6 6  

33 609 AV 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 25 2 1 8 4  

34 609 AW 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 25 8 1 32 4  

35 609 AX 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18       18 2 0 11 0  

36 609 AY 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 17 0 0 0 0  

376100

610 BA 1 2 3 4 5 6 7 8 9 10 11 11 0 0 0 0  

38 610 BB 1 2 3 4 5 6 7 8 9 10 11 11 1 0 9 0  

39

6110

611 BE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 4 1 27 7  

40 611 BF 1 2 3 4 5 6 7 8 9 11 10 12 13 14 15 15 4 3 27 20  

41 611 BG 1 2 3 4 5 6 6 1 1 17 17  

42 611 BH 10 11 12 13 14 15 6 0 0 0 0  

43 611 BI 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 17 0 0 0 0  

44 611 BJ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17             17 0 0 0 0  

                                     

Total Total no of spots & spot with spatter 649 88 60 14 9  

List of Activities Carried Out for Spatter Reduction

1. Shank Misalignment Corrected2. Improper Gun angle during tip dressing corrected3. Improper Gun angle during welding corrected4. Gap between tip and work piece reduced5. Parameter change

MovableTip

FixedTip

MovableTip

FixedTip

List of Activities Carried Out for Spatter Reduction

1. Shank Misalignment Corrected

Tip Dresser

Tip Dresser

List of Activities Carried Out for Spatter Reduction

1. Improper Gun angle during tip dressing corrected

List of Activities Carried Out for Spatter Reduction

1. Improper Gun angle during welding corrected

GAP

List of Activities Carried Out for Spatter Reduction

1. Gap between tip and work piece reduced

List of Activities Carried Out for Spatter Reduction

1. Parameter change

Results : Spatter Graph – Robot wise

Results : Spatter Graph – Station wise

Main Body Spatter Percentage

Results Achieved

TOTAL NO OF SPOTS : 649

SPOTS WITH SPATTER : 88

AVG SPATTER % APR-13 : 14%

AVG SPATTER % AUG-13 : 9%

Under Body Spatter Percentage

Results Achieved

TOTAL NO OF SPOTS : 657

SPOTS WITH SPATTER : 161

AVG SPATTER % APR-13 : 25%

AVG SPATTER % JULY-13 : 16%

• Layout and Process of Weld Shop B• Spatter Reduction Procedure using Different

Techniques, as well as Procedure Efficiency• Basic Robotic Operation• Operation Analysis System(OAS)• Stop Rate Analysis for Line Efficiency.

Project Learning