What is Cpk vs PPK?

What is Cpk vs 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 does Cpk value mean?

Cpk is a standard index to state the capability of one process, the higher the Cpk value the better the process is. For instance, Machine 1 has a Cpk of 1.7 and machine 2 has a Cpk of 1.1. From the Cpk value, one can derive that Machine 1 is better than 2.

What is Cpk in pharmaceutical?

Process Capability (Cpk) and Process Performance (Ppk) are two statistical metrics that consider the variation of the process against its specification. They are widely used to grade the performance of the process to meet its specifications (Table 3).

What is Cpk formula?

The formula for the calculation of Cpk is Cpk = min(USL – μ, μ – LSL) / (3σ) where USL and LSL are the upper and lower specification limits, respectively. A process with a Cpk of 2.0 is considered excellent, while one with a Cpk of 1.33 is considered adequate.

What does PPK of 1.33 mean?

1.33 ≤ Ppk ≤ 1.67 The process may not meet customer requirements. After part approval, begin production with additional attention to the characteristic until an ongoing Cpk ≥ 1.33 is achieved. Ppk < 1.33. The process is substandard for meeting customer. requirements.

Why PPK is higher than Cpk?

The automotive confusion aside, Ppk will always be greater than Cpk since Ppk is long term capabliity and Cpk is short term capability. The only way that Cpk will be greater than Ppk (other than a misuse of the terms and formulas) is under the conditions stated in a previous post.

What is the difference between CP & Cpk?

The Cp and Cpk indices are the primary capability indices. Cp shows whether the distribution can potentially fit inside the specification, while Cpk shows whether the overall average is centrally located. If the overall average is in the center of the specification, the Cp and Cpk values will be the same.

What is difference between CP and Cpk?

1. Cp is the simplest indicator of a process capability while Cpk gives a better picture. 2. Cp is also known as the “process potential index” while Cpk is known as “process capability index” or “process performance index”.

Why is PPK higher than Cpk?

How many ppm is 1.33 Cpk?

Sigma level table