A low volume production process capability analysis

Statistical Process Control (SPC) and Process Capability Indices (PCI) are used extensively within manufacturing and service environments. This paper reports the results of a statistical quality improvement programme when applied to a low volume, high gauge frequency machining process. The resultant capability indices (Cp and Cpk) are calculated from acquired data both before and after process modification, and are discussed in relation to the specific process. Box Cox data transformations are utilised in order to centralise data and the applicability of the capability improvements are determined. Historically SPC and capability analysis are performed on high volume processes with data being gathered on a sample basis. This investigation applies the high volume theory to a low volume 100% data gathering process. The validity of capability analysis of this nature is discussed due to long cycle times and large gauge inspection frequency