Learn How to Calculate Pp & Ppk - Tutorial, Definition and Example

Learn How to Calculate Pp & Ppk - Tutorial, Definition and Example

Process Performance (Pp) Definition:

Process Performance denotes whether a process is performing correctly in a certain period of time within the overall requirement. It calculates the measurable property of a process.

Process Performance Index (Ppk) Definition:

Process Performance Index is nothing but an estimation of the capability of the process during its initial set-up. It demonstrates how a process is able to create the output to its overall specifications.

Formula :  Where,

USL = Upper Specification Limit, LSL = Lower Specification Limit.

Example :

Food kept at a restaurant should be between 38°C and 49°C . The process used to keep the food at the same temperature has a process standard deviation of 2°C. What is the process performance of the process?

Given,

USL (Upper Specification Limit) =49°C LSL (Lower Specification Limit) =38°C Standard Deviation =2°C Mean = (49 + 38)/2 = 43.5

To Find,

Process Performance & Process Performance Index

Solution:
Process Performance :
Process Performance = (49 - 38) / (6 * 2)
= 9 / 12
= 0.917
Process Performance Index :
Solution 1
(USL-mean/ 3*std.Dev) = (49 - 43.5) / (3 * 2)
= 0.917
Solution 2
(mean-LSL/3*std.Dev) = (43.5 - 38) / (3 * 2)
= 0.917
Now, find the minimum value.
Process Performance Index = min (Solution 1, Solution 2)
= min (0.917 , 0.917)
= 0.917