Measurement variation study. A study was done to evaluate the measurement of the flushness of a fitted assembly. The measurement process simulated the assembly by clamping the key part into a fixture constructed for the purpose. Then a micrometer was used to measure the flushness (the gap at a critical location between the part and the fixture). Measurements were in fractions of a millimeter.

Ten parts were selected from the process during a period when the process was stable. Each part was placed in the fixture (a setup)

two different times, and the micrometer measurement was performed twice after each setup. The 20 setups were done in a random order. The following data were obtained.

Analyze these data as a three-factor nested design. Prepare a run chart and a dot-frequency diagram. What is the biggest contributor to variation of the measurement procedure?

Transcribed Image Text:

Measurement Run order Part Setup First Second 123 6 1 0.75 0.80 2 2 1 0.50 0.55 10 1 0.65 0.70 4 3 1 0.40 0.50 5 6 2 0.60 0.60 6 9 1 1.95 1.80 7 1.80 1.90 8 9 2 1.90 1.75 9 1 1 1.70 1.70 10 1 1.65 1.75 11 5 1 1.50 1.40 12 7 1 1.30 1.40 13 2 1.15 0.95 14 4 2 0.95 1.00 15 5 2 1.00 0.90 16 10 2 0.85 1.80 17 7 2 0.70 0.85 18 8 1 0.70 0.65 120 19 1 20 8 22 2 0.65 0.65 2 0.50 0.55