- Question 2 A Firm Produces Screws That Have To Fit Into A Slot In An Assembly Following Are The Length Of Screw In Mil 1 (40.36 KiB) Viewed 12 times
- Question 2 A Firm Produces Screws That Have To Fit Into A Slot In An Assembly Following Are The Length Of Screw In Mil 2 (36.6 KiB) Viewed 12 times
Question 2 A firm produces screws that have to fit into a slot in an assembly. Following are the length of screw (in millimeter): Sample S1 S2 S3 S4 S5 X R Day 1 46 33 54 46 64 48.6 31 Day 2 52 45 54 75 64 58 30 Day 3 34 64 36 46 63 48.6 30 Day 4 34 45 47 37 62 45 28 Day 5 46 64 75 55 16 51.2 59 a) Using the data in the table, compute the center line, the upper control limit, and lower control limit for the and R charts. (10 Marks) (Note: Refer to Appendix 1 for the formula) b) Is the process in control? Interpret the charts. (6 Marks) c) If the specification is 50.25± 5.0 compute the index process capability Cp and Cpk. Interpret the result. (4 Marks)
Appendix 1 Factor for Control Limit A2 D4 d2 1.88 3.268 1.128 1.023 0 2.574 1.693 0.729 0 2.282 2.059 0.577 0 2.114 2.326 0.483 0 2.004 2.534 0.419 0.076 1.924 0.373 0.136 1.864 0.337 0.184 1.816 n 2 3 4 5 6 7 8 9 Formula for control limit UCL = D. R R LCL = D, R R UCL = x + 4₂ R D3 0 LCL. = X-A₂ R X 2.704 2.847 2.97 Formula for Process Capability Cpk min b USL - LSL 60 11 USL-xx-LSL 30 30