Quick Answer: What Is The Difference Between CP And PP?

What is a good CP value?

By convention, when a process has a Cp value less than 1.0, it is considered potentially incapable of meeting specification requirements.

Conversely, when a process Cp is greater than or equal to 1.0, the process has the potential of being capable.

Ideally, the Cp should be as high as possible..

What does a CP value mean?

Cp is a ratio of the specification spread to the process spread. … Higher Cp values indicate a more capable process. When the specification spread is considerably greater than the process spread, Cp is high. When the specification spread is less than the process spread, Cp is low.

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.

What does a Cpk of 1.67 mean?

The 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 does a Cpk of 0 mean?

No problemMean = 0: No problem. You can calculate Cp and Cpk as you allways do. … This would mean that youe process has no variation, and there is no such a process.

What is PP PPK CP CPK?

Sorry to tell, but definition of Cpk and Ppk is wrong, it´s just the other way round: Ppk is a short term analysis (mostly done with 50 or 100 samples measured) Ppk is Process Potential Capability. Cpk is long term analysis and is Continous Process capability.

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 it called 6 Sigma?

The name Six Sigma is derived from the bell curve used in statistics where one Sigma represents one standard deviation away from the mean. The defect rate is said to be extremely low when the process exhibits Six Sigma’s, where three are above the mean and three below.

What percentage is 4 sigma?

Also, what percentage is 4 sigma? 3 Sigma: 66.8K errors per million (93.3% accuracy). 4 Sigma: 6.2K errors per million (99.4% accuracy). 5 Sigma: 233 errors per million (99.97% accuracy).

What is PP in process capability?

Process Capability Pp measures the process spread vs the specification spread. In other words, how distributed the outcome of your process is vs what the requirements are. … Process Capability & Performance (Pp, Ppk, Cp, Cpk) Overview.

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 is Cp and Cpk formula?

The equation for Cpk is more complicated: [minimum(mean – LSL, USL – mean)] / (0.5*NT). LSL stands for Lower Specification Limit and USL stands for Upper Specification Limit. Often we describe Cpk as the capability the process is achieving whether or not the mean is centered between the specification limits.

What is a good CP and CPK?

We generally want a Cpk of at least 1.33 [4 sigma] or higher to satisfy most customers. 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 CP 1.33 mean?

Process capability indexProcess capability index (Cpk) is a statistical tool, to measure the ability of a process to produce output within customer’s specification limits. … Cpk = or >1.33 indicates that the process is capable and meets specification limits.

What is the maximum value of CP and CPK?

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.