The specification for a plastic handle calls for a length of 6.0 inches ± .2 inches. The standard deviation of the process is estimated to be 0.05 inches. What are the upper and lower specification limits for this product? The process is known to operate at a mean thickness of 6.1 inches. What is the C p and C pk for this process? Is this process capable of producing the desired part?

Question

The specification for a plastic handle calls for a length of 6.0 inches ± .2 inches. The standard deviation of the process is estimated to be 0.05 inches. What are the upper and lower specification limits for this product? The process is known to operate at a mean thickness of 6.1 inches. What is the C p  and C pk  for this process? Is this process capable of producing the desired part?

Getting Craftay · Accepted Answer

Final Answer : LSL = 5.8 inches, USL = 6.2 inches. C p  is (6.2-5.8)/6(.05) = 1.33. C pk  is the lesser of (6.2 - 6.1)/(3*0.05) = .67 and (6.1 - 5.8)/(3∗0.02) = 2.00; therefore, .67. The process is capable based upon the C p . However, the process is not centered (based upon its C pk ) and based upon its current center is not producing parts that are of an acceptable quality.

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