Quality Tools to Reduce Crankshaft Forging Defects: An Industrial Case Study

Crankshafts are the most important loaded components in the case of an automobile. In order to achieve required mechanical properties most of crankshafts for automobile are forged with micro alloyed steel. Usually, the shapes of crankshafts are complex, and many defects are induced during the process of crankshaft forging such as under-filling, laps and folds etc. In this work the forging analysis of six cylinder crankshaft produced by hot forging having engine bore of ninety-seven mm popularly known as 697 crankshaft manufactured by TATA Motors, Jamshedpur INDIA (previously known as TELCO) used in trucks and buses is being made. Forging analysis is being made to explain that how the defects appear and how to prevent them. This analysis can be easily done with the help of various quality tools used for quality improvement process. With the help of Pareto diagrams, which are mostly used to identify critical areas, the forging defects of the crankshaft have been prioritized by arranging them in decreasing order of importance. Then cause and effect diagram is being applied to explore possible causes of defects through brain storming session and to determine the causes which has the greatest effect. Corrective measures are being suggested to overcome the forging defects of the 697 integral counter weight crankshafts. Finally, few remedial measures and suggestions have been provided for the existing crankshaft production line in the forging shop. It is also concluded that the proper implementation of the proposed corrective plan may reduce the present rejection rate from 2.43% to 0.21% and rework from 6.63% to 2.15%.