Topic A: Concurrent engineering, interchangeability and tolerances and Limits and Fits [12]

Figure 1. Map of concurrent engineering.

Q1. Figure 1 shows amap of the concurrent engineering philosophy, identify the missing function in Figure 1.

a. Primary manufacture process

b. Sales

c. Product testing

d. Secondary manufacture process

e. Product design [ 1]

Q2. Which of the following is not a general principal or guideline in ‘design for manufacture and assembly’?

a. Maximise the number of flexible components

b. Use common parts across production lines

c. Design with tolerances that are within process capability

d. Shape parts and products for ease of packaging

e. Minimise the number of components [ 1]

Figure 2. Normal distribution of part sizes produced by a given manufacture process.

Q3. Figure 2 shows the distribution of part sizes produced by a given manufacture process.

State to within 1 decimal place, what percentage of parts will lie between plus and minus two standard deviations from the average part size?

a. 67.3

b. 95.5

c. 75.1

d. 87.3

e. 99.7 [ 1]

Q4. Using the BS4500 standard, a design engineer specifies the following code for the fit   between a hole and a shaft: 30C11h9. If any, which of the following answers in relation to this code is incorrect?

a. the basic size of both the hole and shaft is 30mm

b. the hole has a tolerance grade of 11

c. the fundamental deviation of the shaft is zero

d. the fundamental deviation of the hole is given by the letter ‘C’

e. the fundamental deviation of the shaft is given by the letter ‘h’ [ 1]

Referring to the BS4500 Table of selected fits for holes and shafts (find the tables at the end of this exam paper):

Q5. Choose the correct sizes of the maximum and minimum diameters for the code 18H11 in mm

a. 17.905 & 17.795

b. 18.130 & 18.000

c. 18.052 & 18.000

d. 18.110 & 18.000

e. 18.011 & 18.000[ 1]

Q6. Determine the upper deviation of the code 180F8 and also decide whether this code relates to a hole or a shaft, then choose the correct option from the choices below:

a. 0.122 mm / hole

b. 0.043 mm / hole

c. 120.106  / shaft

d. 0.106 mm / hole

e. 120.106 mm / hole [ 1]

Q7. Choose the correct sizes of the maximum and minimum diameters for the code 245f7 in mm

a. 244.880 & 244.560

b. 244.970 & 244.940

c. 244.988 & 244.965

d. 245.095 & 245.050

e. 244.950 & 244.904 [ 1]

Figure 3. A clutch hub connected to a shaft.

Q8. Figure 3 shows a cast iron clutch hub connected to an aluminium shaft using a 40h6P7

fit. Calculate the allowance of this fit at the maximum material condition, in microns, then choose the correct value from the choices below:

a. -2

b. -42

c. -60

d. 47

e. -24 [2]

Q9. The cast iron clutch hub an aluminium shaft shown in Figure 3 are cooled from room

temperature (20oC) to -80oC. The coefficients of linear thermal expansion of cast iron and

aluminium are 11.8x10-6 and 23.0x10-6 oC- 1 respectively. Calculate the allowance between the two parts at -80oC for the maximum material condition, to the nearest micron.

a. 47

b. - 12

c. 23

d. -8

e. 3

f. None of the above [3]

Topic B: Dimensional Measurement and Surface Texture [10]

Q10. State which of the following dimensional measurement systems is contact-based a. structured light scanner

b. lidar laser

c. scanner

d. co-ordinate measurement machine

e. photogrammetry [ 1]

Figure 4. Setup of a basic laser interferometer.

Q11. A basic  laser  interferometer  that uses  light  of 660  nm  wavelength  is  employed  to investigate the surface of a manufactured part. The interferometer records full brightness when reflected from the bottom of an asperity shown in Figure 4. Use Equation (1) to determine the value of n and state whether the upper surface of the asperity will be light or dark.

diff = nλ/2 Eq (1)

a. 3 & dark

b. 6 & dark

c. 4 & light

d. 4 & dark

e. 5 & light [2]

Figure 5. Closeup of a micrometerscrew gauge.

Q12. You are asked to measure the diameter of a shaft using the micrometer screw gauge

shown in Figure 5. The digital display has malfunctioned so read the gauge manually. Note

that each division on the upper horizontal scale represents 1 mm. Choose the correct measurement from the choices below (given in mm):

a. 5.18

b. 0.56

c. 8.52

d. 5.68

e. 4.58 [ 1]

Figure 6. Measurement produced by a surface profilometer.

Q13. Figure 6 shows a profilometer measurement taken from the surface of a machined part. Calculate the approximate position of the datum line (or centreline) from this measurement. Give your, answer in microns, correct to 1 decimal place.

a. - 1.3

b. 1.5

c. 1.2

d. 2.8

e. 1.8 [3]

Figure 7. Another measurement produced by a surface profilometer!

Q14. In reference to Figure 7, start with your first measurement point located at 0 on the x-

axis, assume the centreline of this profile lies exactly at 0 microns on they-axis and calculate the Rq value of this surface profile. Use a value of n=9 in your calculation. You may find

Equation (2) useful. Calculate your answer in microns correct to 1 decimal place.

R q  =

a. 3.0

b. 4.7

c. 3.3

d. 3.2

e. 2.9

f. None of the above are correct

Eq (2)

[3]

Topic C: Sheet Cutting, Bending and Forming [16]

Figure 8. A burr shown at over 100x magnification, produced along the edge of a sheet metal

after cutting.

Q15. Figure 8 shows atypical burr. If any, which of the following is not a recognised factor that can influence the shape of the burr?

a. the shape of the punch

b. the shape of the die

c. use of lubrication

d. the clearance between the punch and the die

e. the surface roughness of the sheet [ 1]

You are asked to consider the use of a hardened titanium alloy in a sheet forming operation. You are given Equation (10) and asked to perform a test to help evaluate the bendability of  the titanium alloy.

r = × 100                                                                            Eq (3)

Q16. State the name of the required test and state the meaning of ‘r ’ in Equation (3).

a. a Jominy end quench test, r is the hardenability of the alloy

b. a tensile test, r is the reduction in area of the tensile specimen

c. a compression test, r is the Poisson’s ratio of the alloy

d. a Vickers hardness test, r is the indentation depth in the specimen

e. a sheartest, r is the shear modulus of the alloy [ 1]

R = T

Eq (4)

Q17. After some testing, you determine the magnitude of r to be  15. Using Equation (4), determine the maximum thickness of the titanium alloy sheet that you can use if you are to bend the sheet around a geometry with a radius of curvature of 0.4 cm without tearing the sheet. Calculate your answer in mm correct to 1 decimal place.

a. 0.1

b. 1.2

c. 1.7

d. 5.0

e. 22.1 [2]

Figure 9. Schematic showing the initial radius of curvature of titanium alloy sheet, Ri, when a

bending force is applied, and final radius of curvature of the sheet, Rf, after the bending force

has been removed and spring-back has occurred.

= 4 3 − 3 + 1                                                            Eq (5)

Q18. Figure 9 shows the titanium alloy sheet during the bending process. Use Equation (5) to predict the final radius of curvature of the sheet once the bending force has been removed, after bending the sheet to radius of curvature of 0.4 cm. Assume the Young’s modulus of the titanium alloy is 100 GPa and its yield stress is 1000 MPa. Use your answer to Q17 for the thickness of the sheet in the calculation. Give your answer in mm and choose the closest value below.

a. 132

b. 35

c. 72

d. 115

e. 4.9 [2]

Figure 10. Forming limit diagram for a sheet of titanium alloy.

Q19. Figure 10 shows the forming limit diagram of a titanium alloy sheet. At which of the following strains you would expect the sheet to tear?

a. major strain = 50%,minor strain = -20%

b. major strain = 50%,minor strain = 20%

c. major strain = 30%,minor strain = 30%

d. major strain = 40%,minor strain = -20%

e. major strain = 80%,minor strain = -40% [ 1]

Figure 11. Different views of a sheet being formed over a hemispherical shape, you should

recognise this image from your lecture notes.

Q20. Figure 11 shows different idealised perspective views of a sheet being formed over a hemisphere. Imagine the sheet is ‘somehow’ formed over the hemisphere with no stretching in the radial direction and without buckling the sheet. Use trigonometry to calculate the angle 。. Choose the closest answer, given in degrees.

a. 40.2

b. 57.6

c. 62.6

d. 53.2

e. 32.7 [2]

Q21. Use your answer from Q20 to determine the strain in the circumferential direction

acting along the perimeter of the formed sheet. Do not convert your answer to percentage strain and give your answer correct to 2 significant figures.

a. - 16

b. 12

c. -0.16

d. -0.12

e. -0.14 [2]

Q22. There are many different types of sheet forming processes, which of the following is not a recognised sheet forming process?

a. Hydroforming

b. Rubber forming

c. Explosive forming

d. Spin forming

e. Deep drawing [ 1]

Figure 12. A test used to examine the formability of sheet metal.

Q23. Which, if any, is the generally recognised name for the test apparatus shown in Figure 12?

a. Vickers test

b. Rockwell test

c. Flexural test

d. Cupping test

e. Jominy test [ 1]

Read the following text on a particular sheet forming process and then select the most appropriate word or equation to correctly complete the text.

The main determinant on whether a given metal alloy forms well using the (i)

forming process is its strain (ii) coefficient, n. Strain (ii) behaviour   is expressed in terms of true stress and strain (rather than engineering stress and strain) . True  stress is defined as F/A, where Fis force and A is current (hence true) area of specimen (in    contrast engineering stress is F/Ao where Ao the original area before deformation). True strain is defined as (iii) where lo is original length and lis current length

Q24.

a. (i) lubricated

b. (i) large

c. (i) deep

d. (i) stretch

e. (i) flexural [ 1]

Q25.

a. (ii) hardening

b. (ii) softening

c. (ii) reduction

d. (ii) avoidance

e. (ii) drawing [ 1]

Q26.

a. (iii) ε  = (l2 ⁄lo )

b. (iii) ε = (l⁄lo )

c. (iii) ε  = (∆ l⁄lo )

d. (iii) ε  = (l − lo )⁄l

e. (iii) ε  = l − (l⁄lo )

f. (iii) ε = ln(l⁄lo ) [1]

Topic D: Materials & Process Selection and Costing [17]

Selection Problem 1

You are asked to select the best material to manufacture the lightest possible piston connection rod  for  an  internal  combustion   engine.  The  connection  rod  is   designed  to  transmit  a compressive load from the piston to the engine. It must not buckle due to the compressive load or fail due to fatigue. A diagram of the rod, showing symbols indicating the force and the main dimensions of the connection rod is given in Figure 13. Note the rod has a rectangular cross- section.

Figure 13. Schematic of a piston connection rod showing force, F, and the main dimensions of

the rod.

Q27. According to the systematic selection procedure discussed in this course, what are the free variables in Selection Problem 1?

a. material and cross-sectional area

b. density and cross-sectional area

c. cross-sectional area and mass

d. material and density

e. mass and material [ 1]

Q28. Still referring to Selection Problem 1, you are asked to write down the mass, m, of the connection rodin terms of the; cross-sectional area, A = b × w, density, P and length,L.

Choose the correct equation and the meaning of the symbol, β .

a. m = where β is a factor to account for the stress concentration in the bearing houses

b. m = A2βPL where β is a factor to account for the stress concentration in the bearing houses

c. m = AβPL2  where β is a factor to account for the extra mass of the bearing houses

d. m = A2βPL where β is a factor to account for the extra mass of the bearing houses

e. m = AβPL where β is a factor to account for the stress concentration in the bearing houses [ 1]

Q29. Selection Problem 1 suggests that the rod should be designed to resist failure due to

fatigue. Given that the endurance limit of the material is given as σe , choose the equation that correctly embodies this requirement.

a. ≤ σe

b. F ∙ A ≥ σe

c. ≤ σe(2)

d. ≥ σe

e. ≥ σe(2)

f. F ∙ A ≤ σe [1]

Q30. Using the equations you chose in Questions 28 & 29, eliminate the cross-sectional area, A, in order to find an equation for the lightest connection rod, of mass, m1 , that will not fail    due to fatigue. Arrange the resulting equation such that it contains a material index enclosed   in a bracket. Select the resulting, correctly formatted equation, from the list given below:

a. m1  = βFL2

b. m1  = βFL2

c. m1  = βFP

d. m1  = βFL

e. m1  = βFL

f. m1  = βFP [2]

Q31. Selection Problem 1 also states that the rod should be designed to resist failure due to

compressive buckling. From structural mechanics we know that, in order to prevent buckling the compressive force must not exceed the Euler buckling load, i.e.,

F ≤

where I = b3 w⁄12. In order to include the cross-sectional area, A, in this equation we can write the beam thickness in terms of its width as b  = aw, where a is a dimensionless

constant. Using this information, derive an expression for the cross-sectional area of the

connection rod in terms of the compressive force, F, the rod length,L, the Young’smodulus, E and a, next choose the correct expression from the following choices:

a. A ≥

b. A ≤

c. A ≤

d. A ≥

e. A ≤ L

f. A ≥ [3]

Figure 14 shows the classification system used to identify product geometry in the Cambridge

Engineering Selector (CES) software.

Figure 14. CES shape classification scheme.

Q32. Referring to Figure 14, correctly identify the ‘shape class’ of these extruded aluminium

parts (shown below):

a. Dished sheet

b. Flat sheet

c. Hollow

d. Non-circular prismatic

e. Solid [ 1]

Q33. Referring to Figure 14, correctly identify the ‘shape class’ of this perforated sheet (shown below):

a. Dished sheet

b. Flat sheet

c. Hollow

d. Non-circular prismatic

e. Solid [ 1]

Figure 15. A titanium component.

Cpp  = + Int + 0.51)} + + C(̇)oℎ)                 Eq (6)

Q34. Equation (6) shows a simple cost model. Given the mass of the titanium alloy

component shown in Figure 15 is 0.5 kg and the cost per kilogram of the titanium alloy is

£20, if 20% of the raw material is wasted during the production process, calculate the cost per part due to materials costs.

a. £50.00

b. £31.20

c. £15.00

d. £12.50

e. £13.00 [2]

Q35. Assume the capital costs associated with the sheet forming press are £50,000, and that    the press is used to produce parts like that shown in Figure 13 for 20% of the time. If the loan used to buy the press is repaid over 5 years and the overhead costs are £20 per day, use

Equation (6) to calculate the non-dedicated cost per part if the press produces 30 parts per hour. Give your answer correct to 2 significant figures.

a. £0.22

b. £1600

c. £0.86

d. £220

e. £0.51 [3]

Q36. Use your answers from Questions 34 and 35 and Equation (6) to state the factor by

which the production rate would need to change if the material and non-dedicated production costs were to become equal.

a. about 23 times slower

b. about 57 times faster

c. about 72 times slower

d. about 23 times faster

e. about 57 times slower [2]

Topic E: Iron Production [7]

Read the following text on the production of ferrous alloys and then select the most appropriate words to correctly complete the text.

One of the main purposes of the blast furnace is to strip away oxygen atoms in theiron ore from theiron atoms, by creating (i) , this reacts with the iron oxide in the blast

furnace and a chemical reaction ensues that produces carbon dioxide as a by-product. (ii)

iron is subsequently created in the blast furnace. Because the fuel, (iii) , is in intimate contact with the molten iron, the carbon content of the (ii) iron is very   high, usually between 3 and 4.5 percent. This high carbon content makes (ii) iron   too brittle for most practical engineering purposes and so it has to be further refined. Mass    production of steel from (ii) iron began in 1856 with the introduction of the (iv)

process. This was later replaced by the open hearth furnace, which was superseded later still by the (v) process; the latter remains the predominant steel refinement

process in use today.

Q37.

a. (i) = methane

b. (i) = carbon monoxide

c. (i) = carbon dioxide

d. (i) = nitrogen

e. (i) = hydrogen [ 1]

Q38.

a. (ii) = wrought

b. (ii) = white

c. (ii) = puddle

d. (ii) = cast

e. (ii) = pig [ 1]

Q39.

a. (iii) = carbon

b. (iii) = coal

c. (iii) = charcoal

d. (iii) = petrol

e. (iii) = wood [ 1]

Q40.

a. (iv) = Basic oxygen

b. (iv) = Puddling

c. (iv) = Bloomery

d. (iv) = Bessemer

e. (iv) = Open hearth [ 1]

Q41.

a. (v) = Basic oxygen

b. (v) = Puddling

c. (v) = Bloomery

d. (v) = Bessemer

e. (v) = Open hearth [ 1]

Q42. Figure 16 show the stress versus strain curves of various types of ferrous alloy. Identify [ 1]