Question

Unit6: OPTIMIZING AND CONTROLLING PROCESSES THROUGH STATISTICAL PROCESS CONTROL

1. Define the concept of statistical process control SPC?

2. What is SPC key element?

3. Solving the following problem (Using x -charts and R –charts)?

1 Sample 1 Measured values 2 3 26 24 48 51 4 34 44 2 50 43 3 32 28 26 22 4 52 55 44 ол 16 36 16 36 56 21 35 26 31 7 21 22 18 21 22 8 29 21 23 9 26 44 14 46 22 10 24 22 44

a. Using this data to solve the problem by using X bar chart and R chart?

b. What is the difference between X bar chart and R chart?

c. Draw the control chart for both X bar chart and R chart?

d. Explain the result? 4. Solving the following problem (C -charts)?

e. Using this data to solve the problem by using C chart?

f. What is the difference between C chart and P chart?

g. Draw the control chart for C chart? h. Explain the result?

Answer 1

a) Formula for X-chasto CL= Ua= ☆ + A2 La= T - AZŘ formula for R- chasto CLER UCL= RD4 LOLE R D3

b) X-chart is the mean of values f R- chart is the Largest-smallest values. Both are different

c) control chart for Mean & range chart,

Xbar chart 60 50 40 xbar xbar, ucl,cl,lcl A 30 ucl 소 20 Ich 10 0 1 2 3 4 5 6 7 8 9 10

Conclusion:- The process is out off control.

Range chart 35 30 25 Range 20 Range, ucl, cl, lel ucl 15 cl 10 Ich 5 0 1 2 3 4 5 6 7 8 9 10

Conclusion:- The process is out off control.

d) let, the data as given below, Day Detective 1 2 12 3 10 5 6 6 7 12 9 10 12 9 14 16 13 21 20 16 12 6 18 19 lo to 20

The control chast to be used is thee-chat ēI EC UCL = c +3 to Lal= Ĉ - 3 Control limits for c-chast" - K220, Ec= = 224. X224 īz 11,2 VA- 11.2 +3 x 11,2 Ucuz 17.132 Lela 11,2 - 3 X J 11.2 Ler=5,2682 & c-chart is the no. of detects p- chart for fraction detective, p = d e = I Ec N

g) control chart for c-chart

c-chart 25 20 15 Defectiv defectives, ucl, cl, Icl Uc 10 Cl W Lel 5 0 1 2 3 4 5 6 7 8 9 101112131415161718 19 20

Conclusion:- The process is out off control.