Quick Answer: What Is CP And CPK?

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 CP and CPK in Six Sigma?

In a process qualified as a Six Sigma process (i.e., one that allows plus or minus six standard deviations within the specifications limits), the Cp is greater than or equal to 2.0. … The process capability index, or Cpk, measures a process’s ability to create product within specification limits.

How can I increase my CPK levels?

Q: How can we improve Cpk? A: Reduce the variation, while maintaining the same average. Example 3: The analysis for Diameter 3 has a Cp = 0.43 and Cpk = -0.23. Because Cp is bad, we know there’s too much variation.

What is CP SPC?

Capability (Cp) and performance (Cpk) charts illustrate a process’s ability to meet specifications. Although SPC control charts can reveal whether a process is stable, they do not indicate whether the process is capable of producing acceptable output—and whether it is performing to capability.

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 should be the Cp and Cpk value?

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 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).

What does CPK stand for?

creatine phosphokinaseCPK is the abbreviation for a blood test called creatine phosphokinase. CPK is an enzyme found primarily in muscles. This includes the muscles in the heart. Any muscle injury or damage can cause a rise in the blood level of 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.

Can CPK be negative?

What does a negative Cpk or Ppk Indicate? Yes, it is possible for Cpk and Ppk to be negative. … It is impossible to have a standard deviation be negative so that would mean that x(bar) was larger that the Specification Limit. In other words, the process average is out of specification.

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 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.