Command: SPCProcessCapab

Display all  Hide all

Command: SPCProcessCapab

Calculates the mean, the sigma, and the capability indices of a process.

Input Parameters

ChnList	Specifies one or more channels. Channel list variable A channel list is a Channel or Channel list object, or a text that refers to one or several channels. For more information about the value range, refer to Channel lists.
SPCUSL	Specifies the upper specification limit of a process. Floating-point number variable
SPCLSL	Specifies the lower specification limit of a process. Floating-point number variable
SPCSigmaType	Specifies which method to use for calculating the process sigma. Enumeration variable Enumeration variable with the following selection terms Script Term Interface Term, Explanation "From Range" Based on mean sample range "From StdDev" Based on mean sample standard deviation
SPCSigmaMult	Specifies the sigma multiplier for calculating the upper and the lower natural process limits. Floating-point number variable 0 <= SPCSigmaMult <= 1E300
SPCMovingRangeNo	Specifies the number of samples that are to be included in the moving range if the sample size is 1, which means the channels with length 1. Word variable 2 <= SPCMovingRangeNo <= 25
SPCSigmaTol	Specifies the sigma multiplier for calculating the process capability index. Floating-point number variable 0 <= SPCSigmaTol <= 1E300

Return Parameters

SPCProcessMean	Receives the mean value of a process. Floating-point number variable
SPCProcessSigma	Receives the standard deviation (sigma) of a process. Floating-point number variable σ Specifies the average sample standard deviation. R Specifies the average sample range. mR Specifies the average moving range. c4 , d2 Specifies a factor in relation to the sample size N.
SPCUpperNPL	Receives the upper natural process limit of a process. Floating-point number variable
SPCLowerNPL	Receives the lower natural process limit of a process. Floating-point number variable
SPCCpU	Receives the one-sided upper process capability index CpU. Floating-point number variable
SPCCpL	Receives the one-sided lower process capability index CpL. Floating-point number variable
SPCCp	Receives the process capability index Cp. Floating-point number variable
SPCCpk	Receives the process capability index Cpk. Floating-point number variable
SPCFracNConf	Receives the estimated fraction nonconforming in ppm based on a normal process distribution Floating-point number variable
SPCUFracNConf	Receives the estimated fraction nonconforming in ppm above the upper spec limit based on a normal process distribution. Floating-point number variable
SPCLFracNConf	Receives the estimated fraction nonconforming in ppm below the lower spec limit based on a normal process distribution. Floating-point number variable

Note  Additionally DIAdem saves the calculation results in the following custom properties of the result channel: Result~SPC~ProcessMean, Result~SPC~ProcessSigma, Result~SPC~Limits~UpperNPL, Result~SPC~Limits~LowerNPL, Result~SPC~CapabilityIndexes~CpU, Result~SPC~CapabilityIndexes~CpL, Result~SPC~CapabilityIndexes~Cp, Result~SPC~CapabilityIndexes~Cpk, Result~SPC~NonconformingParts~FracNConf, Result~SPC~NonconformingParts~UpperFracNConf, and Result~SPC~NonconformingParts~LowerFracNConfResultSPCCp.

Example

The following example calculates the mean, the standard deviation, and the capability indexes of a process. The upper specification limit is 5.2 and the lower specification limit is 4.8. DIAdem uses the average sample standard deviation from samples (number of channels) to calculate the standard deviation of the process with the respective sample size N (respective channel length).

Dim oMyChannelList
Set oMyChannelList = Data.GetChannels("Grp/Sample*")
Call SPCProcessCapab(oMyChannelList, 5.2, 4.8, "From StdDev", 3, 2, 6)

oMyChannelList = dd.Data.GetChannels("Grp/Sample*") 
dd.SPCProcessCapab(oMyChannelList, 5.2, 4.8, "From StdDev", 3, 2, 6) 

Dialog Box Call

Call SUDDlgShow("Main", ResourceDrv & "AnaSPCProcessCapab")

Process capability