- What does a Cp of 1.5 mean?
- Why is PPK higher than CPK?
- What is the CPK for 3 sigma?
- What does a PPK of 1.0 mean?
- What is PPK and CPK?
- How many Sigma is 1.67 Cpk?
- What percentage is 4 sigma?
- What does a Cpk of 2 mean?
- What does a Cpk of 1.33 mean?
- What is minimum Cpk value?
- How is PPK calculated?
- What does a low PPK mean?
- What is an acceptable PPK?
- What does CPK 1.67 mean?
- What is CP CPK?
What does a Cp of 1.5 mean?
A Cp of less than one indicates that the process spread is greater than the specification.
This means that some of the data lies outside the specification.
So a Cp of 1.5 means the process can fit inside the specification 1.5 times.
A Cp greater than one is obviously desirable..
Why is PPK higher than CPK?
theoretically Ppk can’t be greater than Cpk. However, it is possible to get Ppk larger than Cpk due to measurement problems (poor resolution or chunky data particularly if you use the Range to estimate the standard deviations) and if you have almost no between subgroup variation…
What is the CPK for 3 sigma?
Relationship to measures of process falloutCpSigma level (σ)Process fallout (in terms of DPMO/PPM)1.00327001.334631.67512.0060.0022 more rows
What does a PPK of 1.0 mean?
Capability indicesPpk is an index of process performance which tells how well a system is meeting specifications . If Ppk is 1.0, the system is producing 99.73% of its output within specifications. … The larger the Ppk, the less the variation between process output and specifications.
What is PPK and CPK?
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.
How many Sigma is 1.67 Cpk?
Sigma level tableTwo sided tableCpk PpkSigma levelPPM out of tolerance1.334.063.3421.504.56.7951.675.00.5738 more rows
What percentage is 4 sigma?
Five-sigma corresponds to a p-value, or probability, of 3×10-7, or about 1 in 3.5 million….Don’t be so sure.σConfidence that result is real3 σ99.87%3.5 σ99.98%> 4 σ100% (almost)4 more rows•Aug 16, 2017
What does a Cpk of 2 mean?
When Cpk is negative it means that a process will produce output that is outside the customer specification limits. … Cpk can have an upper and lower value reported. If the upper value is 2 and the lower is 1, we say it has been shifted to the left.
What does a Cpk of 1.33 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 is minimum Cpk value?
The minimum value of “k” is 0 and the maximum is 1.0. A perfectly centered process will have Cp = Cpk. Both Cpk and Ppk relate the standard deviation and centering of the process about the midpoint to the allowable tolerance specifications. An estimate for Cpk = Cp(1-k).
How is PPK calculated?
Process Mean close to USL If your Process Mean (central tendency) is closer to the USL, use: Ppk = [ USL – x(bar) ] / 3 s, where x(bar) is the Process Mean.
What does a low PPK mean?
process may need improvementGenerally, higher Ppk values indicate a more capable process. Lower Ppk values indicate that your process may need improvement.
What is an acceptable PPK?
According to Six Sigma philosophy, Cp or Pp and Cpk or Ppk should be greater than 1.50. From a technical standpoint, Six Sigma deems a process being acceptable only after achieving a maximum defect rate of 3.4 parts per million opportunities.
What does CPK 1.67 mean?
Excellent, CapableThe Capability Index, Cpk. The outcome of a Process Capability study is a single metric, which provides an indication of the ability of a process to consistently provide output which is within required specifications. CPK <1.00 (Poor, incapable) 1.00< CPK <1.67 (Fair) CPK >1.67 (Excellent, Capable)
What is CP CPK?
Cp and Cpk, commonly referred to as process capability indices, are used to define the ability of a process to produce a product that meets requirements. … Specifications are normally defined in terms of nominal (+/-) tolerances or ranges (low to high.