Indian Welding Journal

S. Manoharan ¹, K. L. Rohira ¹, A. Raja ¹, S. Palani ²

Affiliations
1 Welding Research Institute, BHEL, Trichy, IN
2 Electrical & Electronics Engg. Dept., REC, Trichy, IN

Abstract

A number of power sources are available today from different manufacturers for MIG/MAG welding. Thyristor power sources and transistor power sources are gaining popularity. The performance of MIG/ MAG welding power supplies is heavily dependent on their dynamic properties. However, present day codes are not adequate for evaluating the power source since dynamic properties are not taken in to consideration.

In this paper a simplified method is proposed for evaluation of a given power source which can form guidelines for ordering a new power source as well as to evaluate the same. Evaluation of arc stability, arc ignition and spatter level, are some of the factors considered in the present study.

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K. Asokkumar ¹, C. S. Nizam ², V. R. Samuel ¹, K. G. K. Murti ¹, S. Manoharan ¹, P. Pughazhendi ², V. Ravindran ²

Affiliations
1 Welding Research Institute, BHEL, Trichy - 620 014, IN
2 Boiler plant of BHEL, Trichy - 620 014, IN

Abstract

Flash butt welding is used extensively for welding of steel for different applications ranging from rails to automobile wheels in our country. Although this process is widely used for past six decades, there is still apprehension in adaptation of this process in certain critical applications for want of proper reliable N.D.T. method or proper quality assurance method. The present work addresses this problem of reliable N.D.T. method by suggesting the adaptation of computer based parameter monitoring system for checking every production joint. The first part of the work discusses the development of a P.C. based weld monitoring system. The second part of the work discusses the evaluation of the performance of the developed monitoring system in the actual production environment by welding economiser tube joints.

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K. Asokkumar ¹, V. R. Samuel ¹, S. Manoharan ¹, K. G. K. Murti ¹

Affiliations
1 Welding Research Institute, BHEL, Tiruchirapalli, IN

Abstract

Resistance spot welding is being used extensively in the automobile electrical and consumer goods industries in our country. With high quality coupled with low cost demanded by many industries, it is important to adapt resistance welding controllers for assuring quality of spot welded joints. The present paper examines the dynamic resistance behaviour during resistance spot welding of low carbon steel and austenitic stainless steel with a view to study the applicability of dynamic resistance based controllers Low carbon steel sheet of 1 mm and austenitic stainless steel sheet of 0.5 mm were used for spot welding trials and tensile shear test is used for evaluation of joint quality. Nugget diameter and indentation were again measured. The details of instrumentation system for dynamic resistance measurement and method of computation are being discussed. Dynamic resistance values are computed for every weld trial and parameters such as current pressure and time are varied to study its influence on be: i dynamic resistance as well as tensile shear strength. It was found that there is good correlation between tensile shear load, nugget diameter and indentation with the percentage drop in dynamic resistance. This work suggests that the percentage drop in dynamic resistance can be used as criteria for ensuring the quality of the spot welded steel joints.

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