Process Capability Analysis (Measure Phase) Scope of Module Process Variation Process Capability Specification, Process and Control Limits Process Potential vs Process Performance Short-Term vs Long-Term Process Capability Process Capability for Non-Normal Data Cycle-Time (Exponential Distribution) Reject Rate (Binomial Distribution) Defect Rate (Poisson Distribution) Process Variation Process Variation is the inevitable differences among individual measurements or units produced by a process. Sources of Variation within unit (positional variation) between units (unit-unit variation) between lots (lot-lot variation) between lines (line-line variation) across time (time-time variation) measurement error (repeatability & reproducibility) Types of Variation Inherent or Natural Variation Due to the cumulative effect of many small unavoidable causes A process operating with only chance causes of variation present is said to be “in statistical control” Types of Variation Special or Assignable Variation 台商信息网(大量管理欧亿·体育（中国）有限公司下载) May be due to a) improperly adjusted machine b) operator error c) defective raw material A process operating in the presence of assignable causes of variation is said to be “out-of-control” Process Capability Process Capability is the inherent reproducibility of a process’s output. It measures how well the process is currently behaving with respect to the output specifications. It refers to the uniformity of the process. Capability is often thought of in terms of the proportion of output that will be within product specification tolerances. The frequency of defectives produced may be measured in a) percentage (%) b) parts per million (ppm) c) parts per billion (ppb) Process Capability Process Capability studies can indicate the consistency of the process output indicate the degree to which the output meets specifications be used for comparison with another process or competitor Process Capability vs Specification Limits Three Types of Limits Specification Limits (LSL and USL) created by design engineering in response to customer requirements to specify the tolerance for a product’s characteristic Process Limits (LPL and UPL) measures the variation of a process the natural 6? limits of the measured characteristic Control Limits (LCL and UCL) measures the variation of a sample statistic (mean, variance, proportion, etc) .....