Excellence Manufacturing Sdn Bhd is a plastic injection molding company that producing household plastic products. Steve, the Operation and Quality Director of the company plans to implement few quality control and improvement initiatives such as sampling inspection and statistical process control (SPC) at varies stage of the production line. You have been asked to give the advice of the following.

1. Steve intends to start sampling inspection on the plastic parts produced by the injection molding machine. The plastic parts are produced in the batch of 250. Propose a single sampling inspection plan for the company bases on ANSI Z1.4 standard. Assumed that the company willing to accept Type 1 error of 0.025.

2. The result of sampling inspection is not encouraging. 3 out of the 5 lots are rejected. As such, Steve would like to investigate the cause of failure by using Quality 7 tools. Explain to Steve the 7 quality tools that possibility he could applied and the objective of each tool.

3. To assess the stability of injection molding process, a sub group sample of 6 plastic parts are collected each day and length of the plastic parts are measured. Data collected for a period of 20 days is summarized in the Table 1.0

Table 1.0 Plastic Part Dimension (in mm)

Sample	X-bar	R		Sample	X-bar	R
1	103	4		11	105	4
2	102	5		12	103	2
3	104	2		13	102	3
4	105	6		14	105	4
5	104	4		15	104	5
6	105	3		16	105	3
7	102	7		17	104	5
8	105	2		18	102	2
9	104	4		19	105	4
10	104	3		20	103	2

1. Calculate the control limits for the X-bar and R chart.

2. Compare the control limits calculated in (i) versus data in Table 1.0, does the process seem to be in statistical control? Justify your answer.

Annex A: ANSI Z1.4 standard General Inspection levels Lot size Special inspection level S-1 5-25-3 S-4 1 II III 2 to 9 to 16 to 26 to 51 to 91 to 151 to 281 to 501 to 1201 to 3201 to 10 001 to 8 15 25 50 90 150 280 500 1 200 3 200 10 000 35 000 A A B B B B c A A A B B B c D D D B B c D D E E F A B D E E F G A A B D E F G H J K A B c D E F G H J K L M B D E F G H J K L M N F H Sample stre Sample Acceptance quality limit, AQL, in percent nonconforming items and 0,010 0,015 0,025 0,040 0,065 0,10 0,15 0,100,15 0,25 0,40 0,65 0,40 0,65 1,015 2,5 Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re A 2 1 B 5 01 D E 13 F 20 ! 01 1 12 1112 12 23 1 12 23 32 H SO . 01 f 1 J 80 01 1 12 23 34 56 Annex A: ANSI Z1.4 standard General Inspection levels Lot size Special inspection level S-1 5-25-3 S-4 1 II III 2 to 9 to 16 to 26 to 51 to 91 to 151 to 281 to 501 to 1201 to 3201 to 10 001 to 8 15 25 50 90 150 280 500 1 200 3 200 10 000 35 000 A A B B B B c A A A B B B c D D D B B c D D E E F A B D E E F G A A B D E F G H J K A B c D E F G H J K L M B D E F G H J K L M N F H Sample stre Sample Acceptance quality limit, AQL, in percent nonconforming items and 0,010 0,015 0,025 0,040 0,065 0,10 0,15 0,100,15 0,25 0,40 0,65 0,40 0,65 1,015 2,5 Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re A 2 1 B 5 01 D E 13 F 20 ! 01 1 12 1112 12 23 1 12 23 32 H SO . 01 f 1 J 80 01 1 12 23 34 56