Question 1- Statistical quality control
A small manufacturer of metal rings seals for aircraft engines has been asked by its major customer to
implement SPC. One major type of ring requires cutting a one-eighth wide slot using a milling machine.
The following six samples of five observations each, taken every half hour, are the width of the slots (in
inch) made by the milling machine on the rings.
1
0.1261
0.1253
0.1245
0.1249
0.1248 2
0.1259
0.1263
0.1247
0.124
0.1251 3
0.1239
0.1265
0.126
0.1257
0.1243 4
0.1225
0.1249
0.1265
0.1248
0.1256 5
0.1259
0.1243
0.1242
0.1257
0.1251 6
0.1255
0.1273
0.1245
0.1268
0.1263 a.) Set up the sample mean and range control charts for this operation. Is the process in control?
b.) The seventh sample contains the following values: 0.124, 0.1252, 0.1295, 0.1262, and 0.1275.
Using the control charts from part a, is the process still in control?
Question 2- Given the following list of machines, the standard deviations for their output, and
specification half-width for the job that they may be processed on that machine, using C p determine which machines are capable of performing the given jobs.
Machine Standard Deviation (cm) 001
002
003
004
005 .02
.04
.10
.05
.01 Job half width specification
(±cm)
.05
.07
.18
.15
.04
