CHAPTER 6 TECHNICAL CASE #6

TWELVE SAMPLES, EACH CONTAINING FIVE PARTS IN A SUBGROUP, WERE TAKEN FROM A PROCESS THAT PRODUCES STEEL RODS AT KODZIS FACTORY. THE LENGTH OF EACH ROD IN THE SAMPLE WAS DETERMINED. THE RESULTS WERE TABULATED AND THE SAMPLE AVERAGES / MEANS AND RANGES WERE COMPUTED FOR EACH SUBGROUP. THESE ARE THE RESULTS:

SAMPLE

SAMPLE AVERAGE / MEAN

(inches)

RANGE

(inches)

1

10.002

0.011

2

10.002

0.014

3

9.991

0.007

4

10.006

0.022

5

9.997

0.013

6

9.999

0.012

7

10.001

0.008

8

10.005

0.013

9

9.995

0.004

10

10.001

0.011

11

10.001

0.014

12

10.006

0.009

YOU, AS THE PROCESS ENGINEER, MUST WRITE UP THE ANSWERS TO THE FOLLOWING IN A ONE PAGE SUMMARY AND ON THE SECOND PAGE DRAW BOTH THE X-BAR AND R CHARTS TO HELP ANSWER THE QUESTIONS SHOWN BELOW:

What type of chart is being used and why.

Determine the upper and lower control limits and the overall means (center lines) for both X-Charts and R-Charts

Draw the charts and plot the values of the sample averages and ranges

Does the data indicate a process that is in or out of control?

Why or why not?

BE SURE TO SHOW ALL YOUR WORK (MATH!) FOR YOUR CALCULATIONS!

HINT: The information needed to complete the charts is in the Power Point for Chapter 6 and the Supplement 6 in the text.