Process Capability Assessment with Tool Wear: An Investigative Study

Manufacturing systems are gearing up to meet the challenges of quality‐based competition. Process capability study and analysis have become critical issues in process control and a number of guidelines are available for process capability assessment. However, certain conditions like normally distributed output, statistical independence of observed values and existence of only random variation due to chance causes are stipulated for this assessment. All these conditions may not be completely satisfied in a practical set‐up and departures from these conditions are quite likely to occur. Tool wear is one such dominant and inseparable component in many of the machining processes, and hence it constitutes a systematic assignable cause. Process capability assessment in such cases becomes tricky as the usual procedure will not give accurate results. A real life case study has been considered for detailed analysis. Various approaches of process capability assessment are used. Analyses the results obtained to bring forth a number of critical issues common to such situations. Presents the salient details of the results obtained and various analyses made.