The specifications for a manifold gasket that installs between two engine parts calls for a thickness of 2.500 mm ± .020 mm. The standard deviation of the process is estimated to be 0.004 mm. What are the upper and lower specification limits for this product? The process is currently operating at a mean thickness of 2.50 mm. (a) What is the C p for this process? (b) The purchaser of these parts requires a capability index of 1.50. Is this process capable? Is this process good enough for the supplier? (c) If the process mean were to drift from its setting of 2.500 mm to a new mean of 2.497, would the process still be good enough for the supplier's needs?

Question

The specifications for a manifold gasket that installs between two engine parts calls for a thickness of 2.500 mm ± .020 mm. The standard deviation of the process is estimated to be 0.004 mm. What are the upper and lower specification limits for this product? The process is currently operating at a mean thickness of 2.50 mm. (a) What is the C p  for this process? (b) The purchaser of these parts requires a capability index of 1.50. Is this process capable? Is this process good enough for the supplier? (c) If the process mean were to drift from its setting of 2.500 mm to a new mean of 2.497, would the process still be good enough for the supplier's needs?

Karneeka Golash · Accepted Answer

Final Answer : (a) LSL = 2.48 mm., USL = 2.52 mm. C p  = (2.52 - 2.48)/(6∗0.004) = 1.67. (b) Yes to both parts of the question. (c) The C pk   index is now relevant, and its value is the lesser of 1.917 and 1.417. The process is still capable, but not to the supplier's needs.

Definitions

Learning Objectives

Learning Objectives

Related questions