Formula=(USL-LSL)/6Q
USL:Upper limit of standard
LSL:Lower limit of standard
6Q:Process capability
u:Center of process
CPL:Lower limit process capability index
Formula=(u-LSL)/3Q
CPU: Upper Limit Process Capability Index
Equation=(USL-u)/3Q
CPK: Actual Process Capability Index
Equation=min{CPL,CPU}
Cpk Calculation: (Cpk=1.33 is the best), to determine the data is normal, for the steady state.
MSA: Measurement System Analysis
This is easier to calculate with 6Q's Minitab software
DPU: Defects per Unit
Formula = Defects per Unit
DPO: Defects per Chance
Formula = Defects per Unit (Number of Products * Chance)
RTY: Circulation Throughput Yield
RTY: Circulation Throughput Yield
Cpk calculation: (Cpk=1.33 is the best), determine the data normal, steady state. RTY: circulation pass rate
Formula=P1*P2*P3*.....
P process pass rate
Two factors affect Cpk:
a, standard requirements
b, average
Sampling ---- is designed to address the representativeness of the sample
----Simple Random Sampling: simple random sampling (SRS).
---- Stratified Sampling: stratification followed by selection of sampling method (sampling methods are equal, isobaric, and optimal).
---- Cluster sampling: divide the sample evenly into several parts, then randomly select several small parts, and then select a certain number.
---- Systematic sampling: sampling at certain intervals (suitable for assembly lines, not for fully periodic data).
----Subgroup sampling: sampling at certain intervals (not suitable for fully periodic data).
QC four stages: P plan, D implementation, C inspection, A processing
There are too many things in this area suggest that you go to buy some QC, six sigma management, quality management and other books to see only.