Question

A process is making plastic water bottles for bicycles, and four defects can occur in the course of production: missing cap, scratches, flow lines, and excess flash. Data are collected on these defects in hopes that it will reveal opportunities for improvement. The results from the first 25 samples of size n 100 are shown in the accompanying table. Sample Missi"X Cap Scratches Flow Lines Excess Flash 10 12 13 14 15 16 17 19 10 12 12 21 24 25 2 (a) Construct a c chart from these data. Show all calculations (b) Analyze this chart and comment on any statistical signals. (c) Construct individual c charts for each of the four defects. Comment on the similarities and differences among the four charts. (d) Make a Pareto diagram of the four defects and comment on where problem-solving efforts should be concentrated, taking into consid- eration both the charting results and the Pareto diagram. Explain your reasoning. The final inspection for a truck engine is used to check for visual defects The three defects that occur on this product most frequently are pain runs, improper label alignment, and misstamped serial number. An inves tigation into the reason behind the high defect rate is begun, with sample collected every day for 25 days. The results are shown in the table below Number of Engines Examined Misstamped Serial No Label Misaligned 2 Paint Runs Sample 105 101 102 95 100 98 102 101 97 100 106 101 103 2 7 3 2 5 2 3 2 8 9 10 2 4 12 13 14 15 96 101 Misstamped Serial No Number of Engines Examine Label Misaligned Paint Runs 8 Sample 101 98 103 104 100 100 16 17 18 19 20 9 21 2 6 102 23 2 105 102 24 25 10 (a) Construct four u charts from these data. Show all calculations. Analyze these charts and comment on any statistical signals that appear (c) Make a Pareto diagram of the three defects and indicate which is oc- curring most frequently. Where should quality improvement efforts be focused?

Answer 1

SampleCLUCL LCL In Control TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE 6 4.4 10.6 0.0 3 4.4 10.6 0.0 8 4.4 10.6 0.0 3 4.4 10.6 0.0 9 4.4 10.6 0.0 3 4.4 10.6 0.0 4 4.4 10.6 0.0 5 4.4 10.6 0.0 4 4.4 10.6 0.0 6 4.4 10.6 0.0 4 4.4 10.6 0.0 3 4.4 10.6 0.0 2 4.4 10.6 0.0 3 4.4 10.6 0.0 5 4.4 10.6 0.0 5 4.4 10.6 0.0 5 4.4 10.6 0.0 4 4.4 10.6 0.0 6 4.4 10.6 0.0 2 4.4 10.6 0.0 4 4.4 10.6 0.0 6 4.4 10.6 0.0 5 4.4 10.6 0.0 2 4.4 10.6 0.0 2 4.4 10.6 0.0 10 13 14 15 16 17 20 21 23 24 25 c-ba 4.36

2c 109 n 25 c' = Lc / n = 4.36 Z-value = 3.00 3o control limis are following

12 10 _UCL LCL 1 3 5 7 9 11 13 15 17 19 21 23 25 Sample 5