Enhancing the process capability of machining process of boring tool holder by application of six sigma methodology

Abstract

This paper aims to identify the causes for the rejections of Boring Tool Holders (BTH) and develop a process control plan. From the CTQ characteristics, high rejection rates were due to the variations in key size and bore size dimensions. Define-Measure-Analyse-Improve-Control (DMAIC) approach was adopted to solve the problem. Data was collected and X-bar R control charts were drawn. The process was found not to be in statistical control. Fishbone diagram was constructed, and the root causes were narrowed down to tool wear and improper clamping of angular vise. Corrective actions were taken to make sure the angular vise was clamped properly and the tool life was monitored. This led to the process being in statistical control and thus, process capability analysis was conducted. All the values were found to be within the specification limits. The obtained Cpk values were 1.09 and 1.15 for key size and bore size respectively. This was later institutionalized by developing a process control plan that constituted the control stage.