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Does the definition of the P/T ratio (precision to tolerance) assume that the measurement process is centered at some nominal dimension analogous to the definition of process capability ratio (PCR)?
Is there a separate index for an off-center measurement process scenario similar to the PCRk?
Formulas:
P/T = (6*sigma)/(USL-LSL)
PCR = (USL-LSL)/(6*sigma)
PCRk = min [(USL-mean)/(3*sigma),(mean-LSL)/(3*sigma)]
(the gage/instrument sigma is used in the P/T ratio calculation while the process sigma is used for PCR)
Thanks in advance.
Is there a separate index for an off-center measurement process scenario similar to the PCRk?
Formulas:
P/T = (6*sigma)/(USL-LSL)
PCR = (USL-LSL)/(6*sigma)
PCRk = min [(USL-mean)/(3*sigma),(mean-LSL)/(3*sigma)]
(the gage/instrument sigma is used in the P/T ratio calculation while the process sigma is used for PCR)
Thanks in advance.
