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Owning Palette: Process Statistics VIs

Installed With: Statistical Process Control Toolkit

Given the specification limits and the process mean and process sigma, computes the process capability ratios Cp, Cpk, and Cpkm as well as the estimated process fraction non-conforming in parts per million (ppm). Notice that the fraction non-conforming is valid only if the process is normally distributed. Computes one-sided upper and one-sided lower in addition to two-sided process capability ratios and fraction non-conforming.

	mode (0:two sided) selects whether to calculate two-sided, one-sided upper only or one-sided lower only process capability and fraction non-conforming. By default mode is two-sided. The values Cp and Cpkm are always calculated from both the upper and lower specification limits, regardless of the value of mode. 0 two-sided—Cpk and fraction non-conf are calculated with respect to both the upper and lower specification limits. 1 upper only—Cpk and fraction non-conf are calculated with respect to the upper specification limit only. In this case, Cpk = CpU and fraction non-conf = fraction > USL. 2 lower only—Cpk and fraction non-conf are calculated with respect to the lower specification limit only. In this case, Cpk = CpL and fraction non-conf = fraction < LSL.
	upper spec limit is the upper specification limit of the process.
	lower spec limit is the lower specification limit of the process.
	process mean is the estimated process mean. See the description of the Process Mean & Sigma VI for an explanation of how the values for process mean and process sigma are calculated.
	process sigma is the estimated process sigma.
	sigma tolerance (6) is the sigma multiplier to use in the process capability calculations. If sigma tolerance is left unwired, a value of 6.0 is used by default, which is the tolerance spread most commonly used for process capability calculations.
	CpU & CpL contains the one-sided upper and lower process capability ratios. CpU is the one-sided upper process-capability ratio. By default, 0.5 sigma tolerance=3.0. CpL is the one-sided lower process-capability ratio. By default, 0.5 sigma tolerance = 3.0.
	Cp is the process capability index (also known as PCR or PCI). Cp is always calculated with respect to both the upper and lower specification limits. By default, sigma tolerance = 6.0.
	Cpk is the centered capability ratio also known as the Cpk index. Cpk= MIN(CpU, CpL).
	Cpkm is a centered process capability ratio. where tau=
	fraction non-conf (ppm) is the estimated fraction non-conforming in parts per million based on a normal process distribution.
	U & L fraction non-conf (ppm) contains the estimated fraction non-conforming in parts per million above and below the specification limits. Note  If your process distribution is not normal, the fraction non-conforming estimates are invalid. fraction>USL is the estimated fraction non-conforming in parts per million above the upper spec limit based on a normal process distribution. fraction<LSL is the estimated fraction non-conforming in parts per million below the lower spec limit based on a normal process distribution.