The thickness of a metal part is an important quality parame

The thickness of a metal part is an important quality parameter. Data on thickness (in inches) are given here, for 25 samples of five parts each.

(a)  

Set up X-bar and R control charts for this process. If necessary, revise limits so that no observations are out of control.

(b)  

Estimate the process mean and standard deviation.

(c) Calculate an estimate of the Cpk. Use this ratio to draw conclusions about process capability.

(d) To make this process six-sigma process, the variance ?2would have to be decreased such that Cpk = 2. What should this new variance value be?

(a)	Set up X-bar and R control charts for this process. If necessary, revise limits so that no observations are out of control.
(b)	Estimate the process mean and standard deviation.

The thickness of a metal part is an important quality parameter. Data on thickness (in inches) are given here, for 25 samples of five parts each. Set up X ?bar and R control charts for this process. If necessary , revise limits so that no observation are out of control Calculate an estimate of the CPK. Use this ratio to draw conclusions about process capacity ca4iitbility. (d) To make this process six-sigma process, the variance Sigma 2 would have to be decreased such that Cpk = 2. What should this new variance value be? The thickness of a metal part is an important quality parameter. Data on thickness (in inches) are given here, for 25 samples of five parts each. (d) To make this process six-sigma process, the variance ?2would have to be decreased such that Cpk = 2. What should this new variance value be?

Solution

lIke this all means are calculated and graphed.

The graph will be around the mean and extending both the sides.

RowI	Mean	std dev
I	0.0636	4.53x10-6
II