In other words, it measures how well a process performs. Process capability analysis compares the distribution of sample values to the specification limits (USL, LSL), in order to determine how well a given process meets a set of specification limits. We will also demonstrate process capability and process performance on some example datasets, by using QTrendControl demo software, freely available on this link: Formulas and definition In this article we will explore process capability analysis methodology, trying to explain the difference between process capability and process performance and how to use related statistics to judge whether our process is capable to comply with customer expectations. However, practitioners are often confused how are they used and assessed and what is the difference between them, especially when first time introduced with those terms. The goal of capability analysis is to ensure that a process is capable of meeting customer specifications, expressed by upper and lower specification limits (USL, LSL).Ī set of capability and performance statistics (CPU, CPL, Cpk, PPU, PPL, Ppk) is used to quantify process capability and performance. Process capability analysis is an important part of quality trending and continuous process improvement methodologies, used for assessing and improving process and product quality. Process Performance (Ppk) Process Capability (Cpk) vs.
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