Question

A company making tires for bikes is concerned about the exact width of their cyclocross tires. The company has a lower specification limit of 22.8 mm and an upper specification limit of 23.1 mm. The standard deviation is 0.19 mm and the mean is 22.95 mm. (Round your answer to 4 decimal places.) What is the process capability index for the process?

Answer 1

Process Capability Index

Given

• Upper Specification Limit(USL): 23.1 mm
• Lower Specification Limit(LSL): 22.8 mm
• Standard Deviation(σ): 0.19 mm
• Mean= 22.95 mm

Process Capability Index= (Upper Specification Limit- Lower Specification Limit)/(6 x Standard Deviation)

Putting the value in the formula to calculate the Process Capability Index

Cp = (USL - LSL) / (6σ)

= (23.1 - 22.8) / (6 x 0.19)
= 0.3/1.14

  = 0.2632

Process Capability Index for the Process is 0.2632  

All the very best, take care