Statistical Quality Controls/Stats (MINITAB ONLY)

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IE 672 Industrial Quality Control

Case Study Scenarios - Session #2 Spring 2014

MUST USE MINITAB… NO SUBSTITUTES/NO EXCEL. SHOW ALL

WORK. SUBMIT BY 12:00 PM – MARCH 25, 2014

1. The following data was collected randomly from a production process of medical pouches. The following Burst Strength (in H2O) data were recorded.

26.7 24 25.8 29.2 28.6 23.1 27.7 26.6 28.9 30.7 29 27.2 24.6 28.5 27.8 28 24 30.9 31.7 24.2 23.1 29.8 30.3 22.2 27.1

A. Display the data graphically by constructing i. Stem and Leaf Plot (2 points)

ii. Boxplot (2 points)

iii. Histogram of the data (2 points)

2. Data was collected from a textile finishing process. Samples were collected daily and the number of nonconformities were recorded. (recall more than one

nonconformity can be present on each unit)

Day Number of units

produced

Number of

Nonconformities

1 13 60

2 12 43

3 19 55

4 14 44

5 18 55

6 13 40

7 24 61

8 15 49

9 16 66

10 11 41

a. Construct an appropriate control chart for the above data. (8 points) b. Do any of the points exceed the 3 sigma control limits? (2 points)

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3. The following data was collected from a manufacturing line. Five samples are

taken at random periodically and tested for a particular quality characteristic.

X1 X2 X3 X4 X5

20.3 22.4 23.0 22.3 21.6

19.9 21.6 20.5 20.1 19.3

23.6 21.3 22.7 22.4 20.7

21.1 20.0 18.9 21.0 19.4

23.5 18.0 22.8 20.1 20.7

17.9 20.0 19.2 20.8 21.4

22.7 23.8 23.1 22.0 21.8

21.9 22.7 21.7 22.5 20.4

19.5 20.6 22.0 20.5 19.5

20.5 22.3 23.6 22.4 21.5

20.9 18.6 17.9 18.1 19.7

20.2 21.0 21.2 20.6 21.2

20.1 20.1 21.4 22.6 20.1

20.9 19.4 17.0 22.4 21.0

19.0 22.0 15.9 21.3 21.6

a. Construct either an X-bar and R chart or an X-bar and S chart on the process. (5 points)

b. Estimate the process standard deviation. (2 points) c. Plot the charts. Applying the western electric rules, is the process in Statistical Control? (3 points)

4. A particular manufacturing process is monitored by sampling one at a time

(subgroup size = 1). The individual data from the last 30 points are given below:

Sample X Sample X

1 43.5 16 38.0 2 38.1 17 34.0 3 38.7 18 41.0 4 42.0 19 39.1

5 39.3 20 41.5 6 38.8 21 39.7 7 38.3 22 40.5 8 41.8 23 39.8 9 41.9 24 41.6 10 39.0 25 42.9 11 38.3 26 43.0 12 40.1 27 41.3

13 41.0 28 37.0 14 34.4 29 39.5

15 36.5 30 41.4

a. Construct an Individuals chart (3) b. Construct a MA Chart (3) c. Construct either a Cusum or EWMA chart(3)