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Introduction to Short-Run SPC
Published in William A. Levinson, Short-Run SPC for Manufacturing and Quality Professionals, 2023
The simplest form of short-run SPC uses the deviation from the nominal method (AIAG, 2016, Chapter 1). Applications consist of processes with oneset of specification limits and one process standard deviation. This chapter will focus only on the latter. Subsequent chapters will address the applications that involve multiple specification limits, multiple product features, and/or part or feature-specific standard deviations. The process standard deviation comes from either (1) surrogate or similar processes or (2) the specification limits and required process performance index, as discussed previously. The deviation from nominal (dnom) is then simply the individual measurement X or the sample average x-bar minus the nominal, and the center line is then zero. dnom=X−μtargetordnom=x¯−μtarget
Manufacturing Quality Control and Tire Uniformity
Published in Brendan Rodgers, Tire Engineering, 2020
The Process Performance Index (Pp) relates the performance to the specification tolerances Pp=[UpperStatisticalLimit(USL)–LowerStatisticalLimit(LSL)]/6s
Tertiary Recycling of Plastic Solid Waste for Additive Manufacturing
Published in Rupinder Singh, Ranvijay Kumar, Additive Manufacturing for Plastic Recycling, 2022
Vinay Kumar, Rupinder Singh, Inderpreet Singh Ahuja
The morphological properties i.e. porosity and shore-D hardness (SDH) of composite samples were observed to investigate the effect of the 3° recycling process on the PVDF composite for 3D-printing applications. Finally, the process capability and performance capability of the proposed recycling method was investigated in terms of process capability (Cp), process capability index (Cpk), process performance (Pp), process performance index (Ppk), and overall standard deviation for process capability (σ).
A recommended set of indices for evaluating process health
Published in Quality Engineering, 2020
Kevin White, John Szarka, Ashley Childress, Willis Jensen
The biggest improvement opportunities are typically when out-of-specification material is being produced. This can be very costly to an organization as it leads to extra process steps (e.g. blending or re-work), selling at a reduced price, scrap, or even off-spec material reaching a customer. In this light, it seems logical to start with an index that looks at actual process performance compared to specifications. The process performance index Ppk is a natural first index to examine because it considers the process average and the long-term standard deviation. Ppk and similar indices have been described in many places, including by Kane (1986), Steiner, Abraham, and MacKay (1997), and Mitchell (1999). Generally, Ppk values less than 1.0 are indicative that out-of-specification material is being produced. where
Implementation of an operating procedure for quality control at production level in a RMG industry and assessment of quality improvement
Published in The Journal of The Textile Institute, 2018
Chowdhury Jony Moin, A. B. M. Sohail ud Doulah, Mohammad Ali, Ferdous Sarwar
Cpk: Process performance index is the measurement of process capability with respect to mean. It measures capability of the process at the specification limit, which has the highest chance of a part going beyond the limit. And naturally, that side will have the highest chance, to which the process has shifted. So, the performance of the process is measured both on the upper side and lower side of the specification by Cpu and Cpl, respectively, and process performance index is the minimum of them.