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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 1 Examinations 2009/
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_Y4, EPPTN_8_Y4, EAMTN_8_Y
Module Title: Quality Engineering
Module Code: MANU
External Examiner(s): Internal Examiner(s): Micheal P O’Mahony , Sally Bryan
Instructions: Answer THREE questions
Duration: 2 Hours
Sitting: Winter 2009
Requirements for this examination: None
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you are attempting the correct exaination. If in doubt please contact an Invigilator.
Q. 1
A hospital processes insurance forms. Errors and missing information on insurance forms lead to confusion and delays. As a result, every claim form has to be checked and corrected before being sent out to the insurance company. The number of defects (mistakes or omissions) were documented for four weeks. The data is presented below. Day Sample size
Defects Average Defects/form (^1 53 101) 1. (^2 64 80) 1. (^3 59 115) 1. (^4 52 127) 2. (^5 65 99) 1. (^6 60 57) 1. (^7 56 99) 1. (^8 49 109) 2. (^9 53 100) 1. (^10 59 121) 2. (^11 66 113) 1. (^12 65 156) 2. (^13 58 142) 2. (^14 55 114) 2. (^15 57 147) 2. (^16 55 113) 2. (^17 61 109) 1. (^18 60 115) 1. (^19 68 98) 1. (^20 65 92) 1. Σ 1180 2207 Figure Q1 – U-chart data
a) Is this an example of variable or attribute data? Explain the reasoning behind your answer. (3 marks) b) Explain why a u-chart is the most suitable control chart for this data. (4 marks) c) Construct the control chart (on graph paper in centre of your answer book) include centreline and control limits. (20 marks) d) Briefly analyse the data and discuss the role of control charts in process improvement. (6 marks)
Q. 4
a) Stakeholder analysis is undertaken by the project leader of a Six Sigma project in the define phase. What does stakeholder analysis identify and why might it be useful? (6 marks) b) Process capability is a central tool in the Six Sigma approach. Explain what is meant by process capability. Define the “Sigma score” of a process. Draw a diagram showing a “5 Sigma” process. (9 marks) c) A product has an nominal length of 11cm. The tolerance associated with this dimension is ±0.5cm. Inspection is carried out on the length and it is found that the mean length is 10.9cm with a standard deviation of 0.47cm. i. Calculate the natural process limits (control limits) (4 marks) ii. State the specification limits (2 marks) iii. Draw the process showing all four limits. In addition shade the proportion of the product that is out side specification. (4 marks) iv. Calculate both capability indices (6 marks) v. Comment on the capability (2 marks)
DATA SHEET
Attribute Chart Formulas
Defectives (Binominal Distributio
p-chart (% Defectives)
n p = np (for fraction) p = npn × 100 (for %)
n LCL p p p
n UCL p p p
3 (^1 )
3 (^1 )
= −^ −
k n =Σ n
n p np 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 u c
k n n
n LCL u u
n UCL u u
n u c
SAMPLE SIZE VARIES
c-Chart (Number of Defects)
LCL c c
UCL c c
k c c
k = number of samples
SAMPLE SIZE FIXED
