Variations in the manufacturing of Rockwell test blocks

Abstract

This research analyzes the variations occurring in the manufacturing of Rockwell hardness test blocks. Test blocks of different materials and hardness were analyzed and the variations were identified using the Ishikawa method. Random samples of 5 blocks were inspected for various parameters such as average thickness, flatness, parallelism and surface finish at each stage. These metrics were then compared and the major sources of variations were identified for different hardness and material. The major sources of variation were found to be due to non-conformance of the process plan, due to the variations in the CNC machine and due to the insufficient training of the workers. Improvements suggested in the machining plan could lead to reduction in machining time at grinding operation by as much as 13%.