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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Autumn Examinations 2008/
Module Title: Quality Engineering
Module Code: MANU
School: Mechanical & Process Engineering
Programme Title: Bachelor of Engineering (Hons) in Biomedical Engineering
Bachelor of Science (Hons) in Process Plant Technology
Bachelor of Science (Hons) in Advanced Manufacturing
Technology
Programme Code: EBIOM_8_Y3, EPPTE_8_Y4, EAMTE_8_Y
External Examiner(s): Mr. Murtagh Murphy, Dr. David Fitzpatrick
Mr. Neil Kingston, Mr. Joe Phelan
Internal Examiner(s): Sally Bryan
Instructions: Answer THREE questions
Duration: 2 Hours
Sitting: Autumn 2009
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you are attempting
the correct examination.
If in doubt please contact an Invigilator.
Q1. a) Give four situations in which Acceptance Sampling may be appropriate method in a
quality management system. (8 marks)
b) Interpret the ASN (average sample number) curve shown in figure Q1. (9 marks)
c) Obtain a single sampling plan using ANSI/ASQC Z1.4 tables. The lot size submitted
for inspection is 2000, and it is agreed that the AQL should be 1.0%. The normal
inspection level will be adopted. (12 marks)
d) How would the plan in part c) change if you were to find 2 out of 5 consecutive lots
rejected? (4 marks)
Figure Q1 – ASN Curve
Q2. (a) In the context of a six sigma project, what should a problem statement include?
(6 marks)
(b) The following is a list of improvement tools used in six sigma projects. Describe
how each one is used and detail what they contribute to a Six Sigma project. Use
diagrams where appropriate.
i. Gauge R&R
ii. Process Mapping
iii. FMEA (27 marks)
Q3. (a) Explain the difference between variable and attribute data. (7 marks)
(b) Each car produced on an assembly line is examined for paint blemishes on the left
front door. Although these blemishes are not obvious to the naked eye a trained
inspector with a special light source and magnifying glass can spot them. The
results of the inspection are given in table Q3.
(i) CuSum Chart (4 marks)
0
5
10
15
0 10 20 30 40 50
Sam ple Num ber
Cumulative Sum Score
(ii) Mean Chart (4 marks)
0
2
4
6
0 5 10 15 20
Sample Number
Mean of Samples
(iii) Range chart (4 marks)
0
2
4
6
8
10
12
0 5 10 15 20 25 30 Sample Number
Range of Sample
(c) After performing a process capability study the analyzer has the following choice of
actions,
i. Do Nothing
ii. Change the specification
iii. Centre the process
iv. Reduce variability
v. Accept the losses
Briefly describe each approach, using diagrams where appropriate. (15 marks)
UCL
LCL
UCL
LCL
DATA SHEETS
Attribute Chart Formulas
Defectives (Binominal Distribution )
p-chart
(% Defectives)
n
np p = (for fraction)
= × 100
n
np p (for %)
n
p p LCL p
n
p p UCL p
k
n n
n
np p Σ
SAMPLE SIZE VARIES
np-Chart
(Defectives)
LCL np np p
UCL np np p
k
np np
k = number of samples
SAMPLE SIZE FIXED
Defects (Poisson Distribution)
u-Chart
(Average number of defects)
n
c u
k
n n
n
u LCL u
n
u UCL u
n
c u
SAMPLE SIZE VARIES
c-Chart
(Number of Defects)
LCL c c
UCL c c
k
c c
k = number of samples
SAMPLE SIZE FIXED
