Reduction of Splatters in Intercell Welding of a Lead Acid Battery

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REDUCTION OF SPLATTERS IN INTERCELL WELDING OF A LEAD ACID BATTERY Boggiti Manikanta1, Shiva sankar2 1PG

Scholar, Mechanical Engineering, Chadalawada Ramanamma Engineering College, Tirupati, A.P, India.

Professor, Mechanical Engineering, Chadalawada Ramanamma Engineering College, Tirupati, A.P, India.

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Abstract - Splatters are the major losses in resistance welding process. Splatter or weld splash is the unwanted creation of small metal particles that are expelled from the welding area during the welding process. These small metal particles can be airborne in the form of “hot sparks” or can solidify as small “balls” or “filaments” that remain loosely attached to the welding area. Excessive weld splash can be an indicator of a weld joint filled with voids and cracks, which can propagate with vibration and temperature cycling to create a future, weld failure. In this paper, I am here to reduce the splatters by varying the electrode geometry. In order to reduce these losses, there was many people have studied and did many researches. The researches may be did by varying the weld parameters such as weld current, weld time, cool time, pressure and squeeze time. By playing all these parameters they might have reduced the splatters to some extent. But in fact the amount of heat generated during welding process plays a major role in production of splatters. Splatter losses are mainly due high heat generated during the welding. So I would like to concentrate on distribution of heat generated during welding and control the splatters by increasing the surface area of the electrodes.

Key Words: Splatters, Resistance welding, Weld current, Weld time, cool time, pressure and squeeze time, Thermo electric process 1. INTRODUCTION

Heat generation in resistance welding is takes place by heating phenomenon. The heat generated depends upon the current, the time the current is passed and the resistance at the interface. The resistance is a function of the resistivity and surface condition of the parent material, the size, shape |

Fig.1 Illustration of resistance welding process Generally, amount of heat generated during resistance welding process is given by the following formula: Heat = I^2xRxT Where I - Weld current applied on work piece R- Work piece electrical resistance in Ohms T- Weld time in milli seconds 1.1 Literature Review

Resistance spot welding is a process in which coalescences produced at two faying surfaces by heat generated at the joint to form lap joint. Spot welding produces single spot like welds, which are called nuggets. The heat is generated by resistance to flow of current though the work piece.

Electrodes are located on both sides of the work piece in which one is movable and other is fixed. The advantages of spot welding include cost efficiency, good dimensional accuracy and reliable production. Without large deformation, it can be used for joining of several metallic materials and sheets of different thicknesses together.

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and material of the electrodes and the pressure applied by the electrodes.

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Literature review has been done for analyzing the process parameters and their effect on the response variables of the resistance welding. Gajanan S. Gaikwad[1], reviews on various effects of process parameters on response variables.

Input parameters such as welding current, weld time, electrode force and electrode geometry effects on the response variables such as tensile strength, hardness, nugget size. He used ANOVA and Taguchi has been most efficient and powerful tool for optimization of resistance welding response parameters which produce high quality parts rapidly and low cost. A. G. Thakur, T. E. [2] says that the amount of resistance at the interface of the work piece depends on the heat transfer capabilities of the material, the material’s electrical resistance, and the combined thickness of the materials at the weld joint.

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M. Vural et al. [3] has done study on the fatigue strength of resistance spot welded galvanized steel sheets and AISI 304 sheets. The results show that galvanized steel sheet combination has the highest fatigue limit. The sheet combination which has minimum fatigue limit is galvanizedAISI 304 sheet combination. D.S. Sahota [4]. The objective of this work is to study the effect of parameters on resistance spot weld of ASS316 material.

2.2 Splatters in cell to cell welding

1.2 Inter cell Welding machine and operation Fig -4: Defect joint in the battery i.e., splatter cell 2.3 Electrode wears out

Fig -5: Electrode condition after 40000 batteries welding Fig -2: Schematic representation of Inter cell welding operation in a battery Two work pieces are joined together firmly by squeezing the electrodes with the help of hydraulic pressure. Weld start time and squeeze time plays a major role in welding process.

Each connected joint cell gives 2V. There are totally 6 cells are there. So totally 12V will be the battery output.

2.4 Impact of the problem: 1.

2.

3.

4.

3 ANALYSES 3.1 4W1H technique

2. PROBLEM IDENTIFICATION 2.1 Sound weld in cell to cell welding

•

WHAT • Splatters in Inter cell welding operation

•

WHEN • While welding operation WHERE • At weld nugget WHO • Quality and productivity HOW • By analyzing the problem and causes

• • •

3.2 Brain storming

Fig -3: Internal weld structure of the cell

 

Sound weld structure should be as shown in Fig.3 after destructive test. © 2017, IRJET

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Low Productivity Battery life reduced Low quality Increasing scrap percentage

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Hydraulic oil pressure Weld start time

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Weld cool time High weld current Squeeze length Electrode Contacting area less Electrode wear out Less flag width Tip gap variation Improper alignment Container hole variation & flashes in hole Operator awareness Improper cooling of flags Material composition

• • • • • • • 3.3.5

Material Material composition Electrode wear out Flag alignment disturbed Ribs not provided in container Less flag width Container hole diameter variation PPCP container flashes in holes Majority causes

By using brainstorming technique we have identified the vital few causes.

3.3 Fish bone diagram

• • •

Electrode Contacting area less Tip gap variation Flag alignment disturbed

3.3 WHY-WHY Analysis Cause: 1- Electrode contacting area less

3.3.1 • • • • • • 3.3.2 • • • 3.3.3 • • •

Machine Hydraulic pressure Weld start time Squeeze length Weld cool time Weld current Tip gap variation

Cause: 2- Tip gap variation

Man Operator awareness Less trained Lack of skill and competency Method Electrode contact area Insufficient cooling of electrodes Insufficient cooling of jaws

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Cause: 3- Flag aligned disturbing

3.3.2 Proposed electrode geometry

3.4 Developing solutions Table-1: Solutions identified S.No

Cause identified

Solution implemented

1

Electrode Diameter (contacting area) less than the flag width Tip gap variation

Electrode outer diameter increased

2 3

Flag alignment disturbed

Hardened bolt used & Lock nut provided Ribs provided in container to locate flags

Fig.7 Propesed electrode drawing outline 3.4 Comparison between Existing and proposed electrode

3.3.1 Existing electrode geometry

Fig.8 Pictorial represntation of electrode surface area Existing electrode is having less contact with the work piece.

So heat distribution is not uniform as less surface are of the electrode. Amount of heat dissipated will melt the joint at the time of welding leads to splatters. The proposed electrode is having very good contact with the work piece. So heat distribution is uniform and splatters are reduced at most extent.

Fig.6 Existing electrode drawing outline

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RESULTS AND DISCUSSIONS

4.1 Electrode outer diameter increased

4.2 Ribs provided in container to locate flags

4.2Hardened bolt used & Lock nut provided

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4.4 Monthly battery production and scrap

5 CONCLUSIONS

Table-2: Month wise battery production and scrap generated Month

Production

May June July August September October November December January February

12365 22172 24939 26354 31820 35528 28210 30435 31775 41843

Defects (Splatters) 503 662 307 186 97 134 100 86 82 110

Percentage 4.07 2.99 1.23 0.70 0.30 0.38 0.35 0.28 0.26 0.26

As we have seen here there is gradual reduction of splatters from month to month. So it is concluded that proposed electrode can bare the amount of heat generated during welding process and that can reduce the splatters in major extent. And finally these proposed electrodes are amended in the engineering product drawing.

REFERENCES [1] Gajanan S. Gaikwad, Dr. K. H. Inamdar. (2016) A review on effect of process parameters of resistance welding, Vol No.4, Issue No.12.

[2] A. G. Thakur, T. E. Rao, M. S. Mukhedkar, and V. M. Nandedkar, Application of Taguchi method for resistance spot welding of galvanized steel, ARPN Journal of Engineering and Applied Sciences, 5, 2010, 22-26.

4.5 Monthly rejection trend

[3] Vural M., Akkus A., and Eryurek B, Effect of weld nugget diameter on the fatigue strength of the resistance welds joints of different steel sheets”, Journal of Materials Processing Technology, 176, 2002, 127-132.

[4] D.S. Sahota et al. study of effect of parameters on resistance spot weld of ASS316 Mechanica Confab ISSN: 2320-2491

Chart-1: Graphical represntation of prosuction Vs scrap 4.5 Intangible benefits    

Increased productivity Learned an effective problem solving methodology & QC tools Ability to take up the new challenges Increased employee morale.

4.6 Tangible benefits  

Expected cost savings / annum Battery scrap reduced from 503 no's to 110 no's 1 battery cost = Rs.5800 Total cost savings = Rs.1.74 millions / annum

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