UNIVERSITY OF SUNDERLAND
FACULTY OF ENGINEERING AND ADVANCED MANUFACTURING
MODULE CODE:  EAT104
MODULE TITLE:  Materials & Manufacturing
MODULE ASSESSOR:  Alan Wheatley
ASSESSMENT:      Two of Two
TITLE OF ASSESSMENT:  Manufacturing Systems and Quality
MODERATED:  KR
PLEASE READ ALL INSTRUCTIONS AND INFORMATION CAREFULLY.
This assignment contributes 50% to your final module mark.
Please  ensure  that  you  retain  a  duplicate  of your  assignment.  We are  required  to
send samples of student work to the external examiners for moderation purposes.  It
will also safeguard in the unlikely event of your work going astray.
THE FOLLOWING LEARNING OUTCOMES WILL BE ASSESSED:
Knowledge
an understanding of:
3.  Modern manufacturing economics, systems and organisation
Skills
and the ability to:
5.  Undertake a costing analysis for a range of product types.
6.  Apply the basic principles of quality control
IMPORTANT INFORMATION
You are required to submit your work within the bounds of the University Infringement
of Assessment Regulations (see your Programme Guide). Plagiarism, paraphrasing
and  downloading  large  amounts  of  information  from  external  sources,  will  not  be
tolerated and will be dealt with severely.  Although you should make full use of any
source material, which would normally be an occasional sentence and/or paragraph
(referenced)  followed  by  your  own   critical  analysis/evaluation.  You  will  receive  no
marks  for  work  that  is  not  your  own.  Your  work  may  be  subject  to  checks  for
originality which can include use of an electronic plagiarism detection service.
Where you are asked to submit an individual piece of work, the work must be entirely
your own. The safety of your assessments is your responsibility. You must not permit
another  student  access  to  your  work.  Where  referencing  is  required,  unless
otherwise  stated,  the  Harvard  referencing  system  must  be  used  (see  your
Programme Guide).
Submission Date and Time  4
th
May 2017
Submission Location  Online
EAT104: Coursework 2: 2016/2017 Session
Manufacturing: Economics, Quality and Organisation
This work contributes 50% of the marks allocated to the module.
This  work  covers  Learning  Outcomes  3,  5  and  6.   Learning  Outcomes  1,  2  and  4  were
covered by the elements within “Coursework 1”.
The  tasks  comprising  this  assessment  are  given  below.  Part  A  comprises  a  series  of
quantitative  questions  relating  to  manufacturing  economics  and  quality  control.  Part  B
comprises CES exercises which relate to manufacturing economics and some environmental
impacts associated with manufacturing.
PART A: Quantitative Analysis
A1.    A company  wishes to introduce a new product. In order to do this, it must invest in
some  new  manufacturing  equipment.   The  choice  is  between  Machine  A  and  Machine  B.
Costs and income associated with each machine are as follows.
Costs / Income  Machine A  Machine B
Fixed Costs  £75,000  £87,000
Variable Cost per Product Produced  £13  £10.50
Selling Price for each Product  £25  £25
Plot  separate  break-even  graphs  (Costs/Income  -v-  No  of  Products)  for  Machine  A  and
Machine B. Which machine would you recommend for purchase? Why?
(15 marks)
A2.  A batch of 2500 components is manufactured by an operator. Each of these components
takes 4 minutes to make. The direct materials costs are £2 per  component. The operator is
paid £15 per hour  (direct labour costs). If the total overheads in this company are calculated
at 350% of direct labour costs, what is the true cost of manufacturing each component?
(10 marks)
A3.   (a)  A  potential  6-year manufacturing  project  requires  the  purchase  of  a  new  piece  of
machinery.   You  are  the  project  manager  and  you  must  choose  between  two  potential
machines (Machine A and Machine B), either of which would be suitable. The cost of each
machine is identical at £80,000. However, they differ in performance such that the projected
future cash flows are different for each machine. Projected cash flows over the 6 years of the
project are as follows in Table QA3:
Table QA3: Six year cash flow figures for Machine A and Machine B.
Year  Cash Flow: Machine A  Cash Flow: Machine B
0  -£80,000  -£80,000
1  £5,000  £35,000
2  £8,000  £25,000
3  £12,000  £18,000
4  £20,000  £10,000
5  £25,000  £7,000
6  £30,000  £5,000
(i)   By  simple  inspection  of  the  cash  flow  figures,  estimate  the  payback  period  for  each
machine and thereby state which machine you would choose and justify your choice.
(ii)   Your  colleague  disagrees  with  your  choice.   Suggest  one  valid  reason  why  your
colleague’s choice may be justified?
(10 marks)
(b)  Calculate the total NPV for  each  machine after 6 years assuming a discount (inflation)
rate of 7% for each year of the project. Table B3b provides a list of discount factors  for a
range of discount/inflation rates.
(10 marks)
(c)  Calculate the total NPV for Machine A only assuming a discount (inflation) rate of 4% for
each year of the project. Hence calculate the Internal Rate of Return (IRR)  for Machine A
over the 6 year period by a graphical method.
(10 marks)
Table B3b. Discount Factors over 6 years for various inflation/discount rates.
A4.  A PVC pipe for water transport is manufactured by  Company A. This extruded pipe has
a  nominal  outer  diameter  of  25  cm  and  the  drawing  specifications  state  that  this  diameter
should be 25cm ± 0.4cm. As part of a Quality Control regime, the pipe is regularly inspected
for compliance to this requirement. Inspections involve diameter measurements on sample
batches of 10 pipes. For each sample batch, the  average  diameter and range  of diameters
are to be found.
Table QA4 gives details of the measurements for 8 successive sample batches.
Sample
Batch  10 x DIAMETER (cm)
1  24.7  25  24.7  24.9  24.9  24.8  24.9  24.9  24.6  24.9
2  25  24.9  24.9  25  25  25.1  25  24.9  24.8  24.7
3  24.6  24.6  24.7  25  24.9  24.9  25  24.7  25  25.1
4  25  24.6  24.8  25  25  24.7  24.8  25  25  24.9
5  25.4  25.5  25.4  25.5  25.6  25.5  25.7  25.7  25.6  25.4
6  25.3  25.4  25.5  25.6  25.6  25.5  25.6  25.6  25.4  25.4
7  25.6  25.7  25.6  25.7  25.6  25.6  25.4  25.3  25.2  25.6
8  25.5  25.6  25.3  25.5  25.5  25.5  25.4  25.5  25.6  25.6
Table QA4. QC data for extruded pipe.
Discount Factors for given discount (inflation) rates over a 6-year project
Years  1%  2%  3%  4%  5%  6%  7%  8%  9%  10%
1  0.9901  0.9804  0.9709  0.9615  0.9524  0.9434  0.9346  0.9259  0.9174  0.9091
2  0.9803  0.9612  0.9426  0.9246  0.9070  0.8900  0.8734  0.8573  0.8417  0.8264
3  0.9706  0.9423  0.9151  0.8890  0.8638  0.8396  0.8163  0.7938  0.7722  0.7513
4  0.9610  0.9238  0.8885  0.8548  0.8227  0.7921  0.7629  0.7350  0.7084  0.6830
5  0.9515  0.9057  0.8626  0.8219  0.7835  0.7473  0.7130  0.6806  0.6499  0.6209
6  0.9420  0.8880  0.8375  0.7903  0.7462  0.7050  0.6663  0.6302  0.5963  0.5645
For the “Average Control Chart”, the Control Limits are 25cm ± 0.2cm and the Drawing Limits
are 25cm ± 0.4cm.
For the “Range Control Chart”, the Control Limit is 5mm and the Action Limit is 8mm.
(a) Calculate (i) the average and (ii) the range for each sample batch.
(10 marks)
(b) Plot the average and range control charts showing the appropriate limits on each.
(10 marks)
(c) Comment on the Quality implications of the data you have analysed.
(10 marks)
A5  The “Economies of Scale” equation may be written as:
C2  = C1 x (Q
2 / Q
1
)
n
where C1 is the known cost of a previous project, C2 is the cost of a new (larger) project, Q1 is
the SIZE of the first project and Q2  is the SIZE of the new project. The index, n,  is a term
which governs how economies of scale apply.
If your original manufacturing project cost  £1,034,564, how much would a new manufacturing
project 3 times the size cost if n = 0.6?
(15 marks)
PART B: CES Exercises on Manufacturing
B1.   Compare  the  manufacturing  processes  of  (i)  manual  green  sand  casting  and  (ii)
gravity  die  casting  in  terms  of  their  respective  economics.  The  component  to  be
manufactured is 20cm in length and possesses a mass of 500g. It is to be manufactured from
a cast aluminium alloy of price £1.75 per kg.
Use  CES  (Edu  Level  3)  to  generate  plots  of  Cost  per  Unit  (£)  – v-  Batch  size  (No  of  units
produced) for each process similar to that shown below:
Use the UPPER
bound as your line for
the basis of
comparison. This
helps avoid ambiguity
in data analysis and
interpretation.
The full set of assumptions on which you should base your plots is as follows:
Economic Factor  Value
Capital Write-Off Time (yr)  5
Component Length (m)  0.2
Component Mass (kg)  0.5
Discount Rate (%)  5
Load Factor  0.5
Materials Price (£/kg)  1.75
Overhead Rate (£/hr)  75
Tasks:
(i)  Manually extract sufficient data points from your CES-generated plots (remember to use
the UPPER line of each plot for your own data set to avoid ambiguity).
(ii) Enter the data into Excel in the following format, or similar:
Batch Size  Cost per Unit (£)
Die Casting  Sand Casting
1  ?  ?
10  ?  ?
100  ?  ?
1000  ?  ?
10000  ?  ?
100000  ?  ?
1000000  ?  ?
10000000  ?  ?
(iii)  Using Excel, plot Cost per Unit (y-axis)  -v-  Batch Size (x-axis) showing both die casting
and sand casting on the same graph.  Use LOG scales for both sets of axes. Label and title
all graphs appropriately.
(iv)  Report  on  your  results.   Discuss  the  comparative  economics  of  the  two  competing
processes in terms of:
(a) the SHAPE of the graph (i.e. why is it this shape?)
(b)  Determine  the  batch  size  at  which  the  cost  per  unit  is  identical  for  both
processes.
(c) Explain why the unit component cost is cheaper for one process at low batch
sizes while cheaper for the other process at larger batch sizes.  Use as many of
the economic factors used (in the assumption table above) as necessary to help
your explanation.
(50 marks)
B2. Two alternative methods of producing  shafts for automotive applications are (i) hot metal
extrusion (for metal shafts) and (ii) filament winding (for fibre composite shafts).
Hot Metal Extrusion
In  HOT  EXTRUSION,  a  compressive  force  is  applied  to  a  metal  billet  to  force  it  to  flow
through a shaped die.
There are two methods: direct extrusion, in  which the die is stationary and the metal is forced
through it by a moving ram. In indirect extrusion, the die itself compresses the stationary billet.
The advantage of indirect extrusion is the lower friction between the billet and the container,
resulting in lower extrusion forces, but the equipment is more complex and the product length
is restricted.
Hot extrusion is limited to ductile metals with room temperature hardness below 6 GPa and
melting points below 2000K. A variant of the process  –  hydrostatic extrusion  –  may be used
with brittle materials. The process is frequently subject to lower tolerances due to effects of
heat and die wear.
Better tolerances can be achieved by cold drawing as a secondary process. Steels usually
require a molten glass lubricant (Sejournet process).
Rolling is frequently more economical for suitable, simple shapes and large production runs.
Process schematic
_
Filament Winding
In FILAMENT WINDING, axisymmetric parts are produced by winding the resin-impregnated
reinforcement (rovings or tape) on a rotating mandrel. The winding pattern could be helical,
hoop or polar depending on the application.
A  multi-axis  winding  spindle  could  be  used  for  winding  more  complex  shapes.  Winding  is
continued until the desired material thickness has been achieved.
The component is pulled off the mandrel as soon as it has hardened. The high reinforcement
content of the process results in products with high strengths. The mandrel is made of either
steel or plaster.
Process schematic
Background
Two candidate materials for the shaft are competing here. The metal shaft will be made using
a  wrought  aluminium  alloy.   The  composite  shaft  will  be  prepared  using  a  glass  fibre  /
polyester resin combination.  The choice of material will determine the manufacturing process
employed (i.e. one of the above two processes).
Tasks
(i) The process economics for hot metal extrusion and filament winding have been calculated
as follows:
Batch Size (n)  Unit Cost (£)  Unit Cost (£)
Hot Metal Extrusion  Filament Winding
1  10021.6  1021.7
10  1021.6  121.7
100  121.6  31.7
1000  31.6  22.7
10000  22.6  21.8
100000  21.7  21.7
1000000  21.6  21.7
10000000  21.6  21.7
Plot these data on a single set of axes (use log axes) of Unit Cost  (y-axis) -v-  Batch size (xaxis).
Which process would you choose for small (<1000 shafts) production runs? Which process would you choose for large (>10,000 shafts) production runs?  Comment on your choices.
(ii)   Your  planned  production  run  is  ≥  10,000  shafts.   You  have  been  instructed  to  take
environmental impact issues of your choice into account as well as the process economics.
Use the “Eco-Audit” tool in CES to  compare the  energy  and CO
2  impacts of  the 2  possible
material / process choices.
Base your environmental impact assessments on the following data.
Materials
i)  A  wrought  aluminium  alloy  (Al  6061  in  T4  condition).  Find  the  alloy  in  CES  via  the
“Material  Universe”  route,  Metals  and  Alloys  /  Non-ferrous  /  Aluminium  /  Wrought  /  6000
series / 6061 / T4)
ii)  A  glass fibre / polyester resin composite  of 75/25 w/w respective composition (find in
CES via the “Material Universe” route, Hybrids…../ Composites / Polymer Matrix / Polyester /
Unidirectional fibre / Filament wound ± 60⁰).
Eco-Variable Inputs
Use inputs to the eco-audit tool as per the following screenshots:
  Generate plots of energy and CO2 impacts for each stage of the shaft life cycle.
  Which shaft material/process would you select if you were seeking to minimise overall
environmental impact (HINT: look at the environmental impact situation both with and
without consideration of “End-of-Life Potential”)?
  Justify your answers.
(50 marks)

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