What is a good PP value?
What is a ‘Good’ Process Capability (Pp) Number? According to Six Sigma, we want a Pp of above 1.5 because that would reflect a process with less than 3.4 DPMO – the definition of 6 Sigma quality.
What is PP in measure?
PP stands for “pearl plate”. It was originally used as a method of measuring pearl sizes with plates, but these days it’s used to measure extremely small products, like the crystal Chaton.
What is PP and CP?
Pp vs Cp (Capability Indices) Both Cp and Pp are a monitoring indices for the spread of your process compared to the specification spread. Cp is used when a process is under statistical control. Pp is used when a process is initially starting out.
What is a good Cpk?
The higher the Cpk, the better is the capability of the process to meet its requirements. In the industry, a Cpk of less than 1.66 needs a closer look. A Cpk that’s less than 1.33 needs some action to make it higher, and a Cpk of less than 1.0 means that the process is not capable of meeting its requirements.
What does a Cpk of 1.67 mean?
Excellent, Capable
CPK >1.67 (Excellent, Capable)
What is a good PP and PPK value?
Many industries use a benchmark value of 1.33. If Ppk is lower than your benchmark, consider ways to improve your process. Compare Pp and Ppk. If Pp and Ppk are approximately equal, then the process is centered between the specification limits.
What does 1.33 Cpk mean?
Cpk = or >1.33 indicates that the process is capable and meets specification limits. Any value less than this may mean variation is too wide compared to the specification or the process average is away from the target.
What sigma is 1.33 Cpk?
4.0
Sigma level table
| Two sided table | ||
|---|---|---|
| Cpk Ppk | Sigma level | % out of tolerance |
| 1.33 | 4.0 | 0.01 |
| 1.50 | 4.5 | 0.001 |
| 1.67 | 5.0 | 0.0001 |
What is Cpk & PPK?
So the key takeaway is that Cpk is the potential of a process to meet a specification (short term) while Ppk is how the process actually did (long term). Another way to look at the difference is that Cpk is used for a subgroup of data, while Ppk is used for the whole process.
What is CP SPC?
Formula for Cp calculation The Cp index does not consider how well (or how badly) the process is centered relative to the specification limit target. Therefore, the Cp is a measure of optimum capability (i.e., what the process is capable of if it were centered, not what the process might be doing).