Analysis of flash butt welding cracks in rim manufacturing

Abstract

Flash butt welding is a well established economical process for solid state butt welding. It consists indirect electrical heating of the ends of the work pieces to be welded and forging them together. While heating, a thermal distribution characterized by a steep temperature gradient is established along the axial length of the pieces. Flash butt welding is widely used for steel band welding m wheel industry. Major advantages are economical in operation, suitable for mass production and high in joint strength. Loadstar (pvt) Ltd has six flash butt machines in different production lines for rim and band manufacturing. The major problem is considerably high amount of scrap percentage due to welding cracks. This problem severely affects the lines which have severe forming or stretching operations in latter stages. For this investigation the line 05 was selected which has high scrap percentage. The main aim of this study is to analyze the flash butt welding cracks in rim manufacturing and to find out the main reasons for the defects. The analysis of flash butt welding cracks in nm manufacturing is done m five stages. In the first stage, attention is paid to literature survey, in which the present stage of the researches carried out in the industry regarding the flash butt welding is discussed. Only few literature sources are available although there are many wheel manufacturing companies-.. in the world. Certainly there might be a lot of researches carried out under this topic in the history,' but due to high competitiveness among the companies the research outcomes might be kept as company secrets. In this project, the analysis of flash butt welding cracks in wheel manufacturing will be discussed in detail. The second stage is process description. .and principles of flash butt welding. Third stage is problem identification and the fourth stage is methodology to solve the problem. In methodology it has stated that the identified process' variables that affect the welding quality and how further testing are carried out. Experimental work and results are reviewed under the fifth stage. In this chapter, the testing done for research is discussed in detail and final conclusion is on how the increasing advance velocity of the movable jaw of flash butt machine while keeping the same voltage will give better results in weld joints for SS 400 material.