Exercise 10

Section 4 Process Capability

Lesson S04-10

Text: Section 4 pages 46 & Section 9 pages 16 – 17

Duration: 15 minutes

Exercise 10

Assess the process capability (using MINITAB) of the O-ring parting line extension data in file Exercise10.MTW. The suggested steps are below. The upper specification limit is 0.08 mm

a. Test the data for normality. What are your findings?

b. Perform a natural log transformation on the data and test the transformed data for normality. What are your findings?

c. Estimate the ppm and Ppk using the transformed data. Remember to also transform the specification limit.

d. Attempt to find a reasonable distribution to describe the original data. Try the Weibull, Lognormal, Gamma, and Loglogistic distributions. What are your conclusions?

e. Use an appropriate distribution to estimate the ppm and Ppk (use MINITAB’s Non-normal process capability option).

Solution / Discussion of Exercise 10