Manufacturing 2

Question 1

a) Which of the following statements is correct?
(i) In slab milling the axis of rotation of the tool is normal to the surface machined.
(ii) In face milling the axis of rotation of the tool is normal to the principal surface machined.
(iii) Slot milling is considered as a slab milling process.
(iv) None of the above.

Answer 1

(ii) In face milling the axis of rotation of the tool is normal to the principal surface machined.

Question 2

b) Assume the following scenario: Face milling operation using a tool of diameter 20 mm and a workpiece width of 15 mm. Which of the following statements is correct?
(i) Moving the tool’s centre along the centre line of the workpiece results in the up and down milling section of the cut to be of equal length.
(ii) Moving the tool to the right will increase the up milling section of the cut.
(iii) Moving the tool to the left will increase the down milling section of the path.
(iv) All of the above.

Answer 2

(iv) All of the above.

Question 3

c) Why do fixed-bridge coordinate measuring machines (CMMs) in general exhibit a higher measuring accuracy than moving-bridge CMMs?
(i) Because of their design, fixed-bridge CMMs exhibit a higher stiffness. As a result, the deformation of the bridge as a result of the weight of the ram is reduced.
(ii) The x-axis movement is placed on the workpiece side, and not on the probe side. Hence, fixed-bridge CMMs exhibit a smaller pre-travel.
(iii) Fixed-bridge CMMs are predominantly made of aluminium. Therefore, their structure is less prone to vibrations.
(iv) All of the above.

Answer 3

(i) Because of their design, fixed-bridge CMMs exhibit a higher stiffness. As a result, the deformation of the bridge as a result of the weight of the ram is reduced.

Question 4

d) With how many measurement points can a CMM determine the radius of a semi-sphere?
(i) Four.
(ii) Five.
(iii) Six.
(iv) All of the above.

Answer 4

(iv) All of the above.

Question 5

e) Which of the following statements is correct?
(i) In down milling, the motion of the cutting tool pushes the workpiece down onto the machine tool’s table.
(ii) In down milling, the tool’s cutting edges enter the workpiece more gently than in up milling.
(iii) In up milling, the thickness of the chip at tool entry is at its maximum.
(iv) None of the above.

Answer 5

(i) In down milling, the motion of the cutting tool pushes the workpiece down onto the machine tool’s table.

Question 6

f) Which of the following cutting parameters has the greatest effect on the cutting temperature?
(i) Feed rate.
(ii) Depth of cut.
(iii) Cutting speed.
(iv) All three parameters affect the cutting temperature to the same extent.

Answer 6

(iii) Cutting speed.

Question 7

g) Which of the following statements is correct?
(i) Cutting inserts for turning tool holders with a negative inclination angle exhibit a stronger cutting edge compared to inserts for turning tool holders with a positive inclination angle.
(ii) Cutting inserts for turning tool holders with a negative inclination angle can have up to eight usable cutting edges.
(iii) Cutting inserts for turning tool holders with a positive inclination angle require a positive flank angle.
(iv) All of the above.

Answer 7

(iv) All of the above.

Question 8

h) In the context of surface metrology, what is meant with positive skewness?
(i) The surface profile exhibits a number of peaks amongst larger areas of plateau-like flat areas.
(ii) The surface profile exhibits a number of deep valleys amongst larger areas of plateau-like flat areas.
(iii) The peaks are inclined in a certain direction, similar to a saw-tooth profile.
(iv) The scanned surface was inclined to the scan direction, i.e. it was not parallel to the movement of the stylus holder.

Answer 8

(i) The surface profile exhibits a number of peaks amongst larger areas of plateau-like flat areas.

Question 9

i) How does a scanning electron microscope (SEM) determine the colour of a target surface?
(i) Different colours emit different quantities of electrons when being hit by the SEM’s electron beam. The colour is identified by mapping a certain quantity of electrons against a reference chart.
(ii) Depending on the colour, surfaces reflect the SEM electron beam differently. This difference in reflection is used by the SEM to determine the colour of the target surface.
(iii) The impact energy of the electrons emitted by the SEM hitting the target surface results in X-rays of different wave lengths, depending on the colour of the target surface. This X-ray wave length is mapped against a colour chart.
(iv) An SEM cannot determine the colour of the target surface.

Answer 9

(iv) An SEM cannot determine the colour of the target surface.

Question 10

j) In the context of scanning electron microscopy, which of the following statements is correct?
(i) Secondary electrons originate from the top-most surface region of the target material.
(ii) Back-scattered electrons originate from the SEM’s electron beam and are reflected by the target material.
(iii) The interaction between target material and SEM electron beam can reach up to several hundreds of nanometres below the target surface.
(iv) All of the above.

Answer 10

(iv) All of the above.

Question 11

k) What is the main reason for the Rockwell method requiring significantly less time for determining the surface hardness of a material than the Vickers method?
(i) Because the load is applied over a much shorter period of time.
(ii) Because the indenter is immediately withdrawn once the maximum load has been applied.
(iii) Because the size of the indentation does not have to be measured in order to calculate the surface hardness. Instead the hardness value is related to the penetration depth and can be directly read from the Rockwell hardness tester.
(iv) Because the surface of the material does not require any special preparation prior to being tested.

Answer 11

(iii) Because the size of the indentation does not have to be measured in order to calculate the surface hardness. Instead the hardness value is related to the penetration depth and can be directly read from the Rockwell hardness tester.

Question 12

l) Which of the following statements is correct?
(i) When trying to determine the surface hardness of a material, any knowledge of the thickness of this material is unnecessary, because, as the name suggests, one only intends to determine the hardness of the surface and not the material underneath.
(ii) The Rockwell B hardness scale is best suited for very soft materials, such as rubber.
(iii) The Vickers test procedure uses a diamond cone in order to reduce the deformation of the indenter.
(iv) Energy dispersive X-ray spectroscopy can be used to very precisely determine the thickness of a thin layer applied to the surface of a component.

Answer 12

(iv) Energy dispersive X-ray spectroscopy can be used to very precisely determine the thickness of a thin layer applied to the surface of a component.

Question 13

m) Which of the following statements is correct?
(i) Diffusion and oxidation wear require higher temperatures to occur. They are less significant at lower cutting temperatures.
(ii) Abrasion wear becomes more pronounced with increasing temperatures.
(iii) Adhesion wear diminishes at higher temperatures.
(iv) All of the above.

Answer 13

(iv) All of the above.

Question 14

n) In the context of tool coating processes, which of the following statements is correct?
(i) Physical vapour deposition (PVD) is a process that requires a high vacuum.
(ii) Chemical vapour deposition (CVD) is a process that can be carried out at room temperature (i.e. 20 degree Celsius).
(iii) PVD allows tools with very complex geometries to be coated uniformly very easily.
(iv) In CVD the coating constituents are provided by either evaporating or sputtering different billets of target materials, such as titanium or chromium.

Answer 14

(i) Physical vapour deposition (PVD) is a process that requires a high vacuum.

Question 15

o) In the context of tool substrates, which of the following statements is correct?
(i) Cemented tungsten carbides are a mix of cobalt grains bonded together by tungsten.
(ii) In order to increase the hot-hardness of cemented tungsten carbides, the tungsten-cobalt substrate is alloyed with tantalum carbides and titanium carbides.
(iii) In order to reduce the brittleness of cemented tungsten carbide, more advanced grades exhibit larger grain sizes and reduced cobalt content.
(iv) A larger grain size allows cemented tungsten carbides to exhibit a higher wear resistance and hardness.

Answer 15

(ii) In order to increase the hot-hardness of cemented tungsten carbides, the tungsten-cobalt substrate is alloyed with tantalum carbides and titanium carbides.

Question 16

p) Which of the following statements is correct?
(i) Crater wear is formed on the rake face of a cutting tool.
(ii) Adhesion wear is the result of atomic bonding of chips and tool substrate and the subsequent fracturing.
(iii) Notch wear is formed on the flank face in areas where there is less intimate contact between tool, chips and workpiece.
(iv) All of the above.

Answer 16

(iv) All of the above.

Question 17

q) In the context of machine tool controls, what is the purpose of the look-ahead function?
(i) It allows the machine tool to look ahead of the path of the cutting tool in order to avoid collisions between tool and workpiece or tool and clamping fixtures.
(ii) It allows the controller to look ahead in the part program in order to determine whether the machine tool’s main spindle is able to provide enough power and torque for the next tool to be operated using the cutting parameters as specified in the part program.
(iii) It allows the controller to look ahead in the part program, so that the controller is aware of the movements the tool is supposed to make after the movement currently being executed.
(iv) It predicts tool wear so that in combination with cutter radius compensation the machine can automatically adjust the theoretical tool diameter by the predicted one.

Answer 17

(iii) It allows the controller to look ahead in the part program, so that the controller is aware of the movements the tool is supposed to make after the movement currently being executed.

Question 18

r) Which of the following statements is correct?
(i) In turning, the cutting speed is determined by considering the workpiece surface to be machined by the tool.
(ii) In turning, the cutting speed is determined by considering the workpiece surface generated by the previous cut.
(iii) In milling, the cutting speed is the velocity with which the tool is advanced over the workpiece surface.
(iv) In turning, the depth of cut is equivalent to the feed rate.

Answer 18

(i) In turning, the cutting speed is determined by considering the workpiece surface to be machined by the tool.

Question 19

s) Whilst carrying out a milling process on a machining centre using an inserted milling tool with double-negative inserts, you observe that the main spindle is struggling to keep the tool rotating. The customer demands that you do not change the tool diameter or the cutting parameters. What could you recommend instead to avoid the problem?
(i) Use a milling tool with more teeth, so that the material removal is distributed over more cutting edges.
(ii) Operate the machining process with a water-based coolant, as this will reduce the cutting temperature.
(iii) Use a cutting tool with double positive inserts.
(iv) None of the above suggestions is going to have any noticeable effect.

Answer 19

(iii) Use a cutting tool with double positive inserts.

Question 20

t) When switching from dry machining to machining using flood cooling, which shear zone will see the smallest effect on the heat generated?
(i) Primary shear zone.
(ii) Secondary shear zone.
(iii) Tertiary shear zone.
(iv) Because all three shear zones are going to get exposed to the presence of the cutting fluid, all three are going to see the same effect on the amount of heat being generated.

Answer 20

(i) Primary shear zone.

Question 21

a) A machine tool is equipped with a CNC controller that does not have look-ahead capability. Which of the following functions can this machine tool not execute?
(i) Canned cycles.
(ii) Cutter radius compensation.
(iii) Tool length compensation.
(iv) Any of the above functions.

Answer 21

(ii) Cutter radius compensation.

Question 22

b) In the context of machine tool controllers, what does point-to-point axis control mean?
(i) The machine tool controller will ensure that each contour point defined in the part programme is reached with sub-micron accuracy.
(ii) The machine tool controller does not control the path of the cutting tool, but only the end points of each movement.
(iii) The machine tool controller controls the path between start and end point of each tool movement.
(iv) The machine tool controller only executes a block once the end point programmed in the previous block has been reached.

Answer 22

(ii) The machine tool controller does not control the path of the cutting tool, but only the end points of each movement.

Question 23

c) What makes a machining centre different to a CNC machine tool?
(i) A machining centre comprises a number of CNC machine tools that are linked together, so that they together can machine parts that a single machine tool on its own is not capable of machining.
(ii) A machining centre can be controlled remotely, whereas a CNC machine tool requires an operator to be present at the machine during its operation.
(iii) A machining centre is equipped with an automatic tool changer.
(iv) There is no difference; both terms refer to the same type of machine.

Answer 23

(iii) A machining centre is equipped with an automatic tool changer.

Question 24

d) When labelling the axes of a machine tool, how do you determine the Z-axis?
(i) It is the longest axis of motion.
(ii) It is the axis that runs parallel to the machine’s main spindle.
(iii) It is always the vertical axis.
(iv) It is always the axis that points towards the front of the machine, towards the operator.

Answer 24

(ii) It is the axis that runs parallel to the machine’s main spindle.

Question 25

e) Which of the following processes is not considered a machining process?
(i) Milling.
(ii) Laser cutting.
(iii) Sawing.
(iv) 3D printing.

Answer 25

(iv) 3D printing.

Question 26

f) In which of the following machining processes is the main cutting motion carried out by the workpiece?
(i) Turning.
(ii) Milling.
(iii) Tapping.
(iv) Drilling.

Answer 26

(i) Turning.

Question 27

g) Increasing the number of teeth on a milling tool whilst maintaining cutting speed and feed rate per tooth allows for what?
(i) Increase in feed velocity.
(ii) Increase in axial depth of cut.
(iii) Increase in spindle speed (i.e. spindle revolutions per minute).
(iv) Use of a less powerful main spindle to drive the tool as each tooth requires less force to remove material.

Answer 27

(i) Increase in feed velocity.

Question 28

h) Which is the dominant wear type when machining with very high cutting speeds?
(i) Abrasion wear.
(ii) Diffusion wear.
(iii) Oxidation wear.
(iv) None of these is dominant, they all occur to the same extent.

Answer 28

(ii) Diffusion wear.

Question 29

i) What is the main cause for crater wear?
(i) Oxidation of the tool substrate as a result of the cutting temperatures.
(ii) Erosion of tool substrate by chip flow in combination with high cutting temperatures.
(iii) The formation and subsequent break-off of built-up edges.
(iv) Diffusion of elements between tool substrate and workpiece material.

Answer 29

(iv) Diffusion of elements between tool substrate and workpiece material.

Question 30

j) Which type of tool wear is most affected by the tertiary shear zone?
(i) Crater wear.
(ii) Flank wear.
(iii) Both crater and flank wear are affected to the same extent.
(iv) Neither crater nor flank wear are affected.

Answer 30

(ii) Flank wear.

Question 31

k) Comparing physical vapour deposition (PVD) with chemical vapour deposition (CVD), which of the following statements is correct?
(i) CVD requires significantly higher process temperatures.
(ii) PVD requires a vacuum within the coating chamber, whereas CVD is an atmosphere controlled process.
(iii) Both PVD and CVD processes can be used to coat tools made of tungsten carbide.
(iv) All of the above.

Answer 31

(iv) All of the above.

Question 32

l) In the context of turning, which of the following statements is correct?
(i) Cutting inserts for tool holders with a positive inclination angle exhibit a stronger cutting edge compared to inserts for tool holders with a negative inclination angle.
(ii) Cutting inserts for tool holders with a negative inclination angle can have up to eight usable cutting edges.
(iii) Cutting inserts for tool holders with a negative inclination angle require a positive clearance angle.
(iv) All of the above.

Answer 32

(ii) Cutting inserts for tool holders with a negative inclination angle can have up to eight usable cutting edges.

Question 33

m) In the context of ceramic cutting tools, which statement is NOT correct?
(i) Ceramics exhibit a high hot hardness and wear resistance.
(ii) Ceramics should not be used in combination with flood cooling.
(iii) Ceramic tools are very suitable for rough machining, where the tool is exposed to strong vibrations.
(iv) Ceramics are suitable for the machining with high cutting speeds.

Answer 33

(iii) Ceramic tools are very suitable for rough machining, where the tool is exposed to strong vibrations.

Question 34

n) In the context of tool coating processes, which of the following statements is correct?
(i) In chemical vapour deposition (CVD) the coating constituents are provided in liquid form.
(ii) CVD only allows tools with very simple geometries to be coated uniformly very easily.
(iii) In physical vapour deposition (PVD) the coating constituents are provided by evaporating billets of target materials.
(iv) All of the above statements are correct.

Answer 34

(iii) In physical vapour deposition (PVD) the coating constituents are provided by evaporating billets of target materials.

Question 35

o) In the context of tool substrates, which of the following statements is correct?
(i) In order to reduce diffusion wear of cemented tungsten carbides, the tungsten-cobalt substrate is alloyed with tantalum carbides and titanium carbides.
(ii) In order to reduce the brittleness of cemented tungsten carbide, substrates exhibit larger grain sizes and reduced cobalt content.
(iii) In order to increase the overall wear resistance, the percentage of cobalt within the substrate is increased.
(iv) All of the above statements are correct.

Answer 35

(i) In order to reduce diffusion wear of cemented tungsten carbides, the tungsten-cobalt substrate is alloyed with tantalum carbides and titanium carbides.

Question 36

p) In the context of tool wear, which of the following statements is correct?
(i) Adhesion wear can cause chunks of the tool substrate to be ripped out from the tool’s rake face by the chips.
(ii) Oxidation wear is responsible for the formation of a wear crater on a tool’s rake face.
(iii) Diffusion wear is responsible for the formation of notches on the flank face.
(iv) None of the above.

Answer 36

(i) Adhesion wear can cause chunks of the tool substrate to be ripped out from the tool’s rake face by the chips.

Question 37

q) In the context of milling, which of the following statements is correct?
(i) In the case of up milling, the workpiece is pushed onto the workpiece holding table, thereby allowing rather thin parts to be machined safely.
(ii) In the case of up milling, cutting tools with negative rake angle and zero clearance angle can be employed.
(iii) In the case of down milling, cutting tools with negative rake angle and zero clearance angle can be employed.
(iv) None of the above statements is correct.

Answer 37

(iv) None of the above statements is correct.

Question 38

r) What does the chip thickness ratio describe?
(i) The ratio between the thickness of the chip at the tool’s rake face and the feed rate.
(ii) The ratio between the thickness of the chip at the tool’s rake face and the thickness of the material layer the tool removes in a pass.
(iii) The ratio between undeformed and deformed chip thickness.
(iv) All of the above.

Answer 38

(iv) All of the above.

Question 39

s) When machining cast iron, which chip type is the most likely to occur?
(i) Continuous chip.
(ii) Continuous chip with build-up edge.
(iii) Discontinuous chip.
(iv) Segmented chip.

Answer 39

(iii) Discontinuous chip.

Question 40

t) In the case that a machining process results in a continuous chip with built-up edge, which of the following statements is correct?
(i) The built-up edge is formed as a result of diffusion of workpiece material atoms into the tool substrate.
(ii) The built-up edge protects the tool’s actual cutting edge, thereby reducing abrasion wear.
(iii) The presence of the built-up edge sharpens the tool’s cutting edge, thereby increasing the machined surface’s finish.
(iv) None of the above statements is correct.

Answer 40

(iv) None of the above statements is correct.

Question 41

u) Which surface quality parameter is affected the strongest by the presence of a single deep scratch on the surface to be inspected?
(i) Maximum peak to valley height.
(ii) Mean peak to valley height.
(iii) Arithmetic mean roughness.
(iv) All three parameters are affected to the same degree.

Answer 41

(i) Maximum peak to valley height.

Question 42

v) How can the trueness of a set of measurements be improved?
(i) By taking a large number of measurements.
(ii) By reducing random errors.
(iii) By compensating for systematic errors.
(iv) By applying all of the above measures/precautions.

Answer 42

(iv) By applying all of the above measures/precautions.

Question 43

w) In the context of scanning electron microscopy, which of the following statements is correct?
(i) Back-scattered electrons originate from the top-most surface region of the target material.
(ii) Secondary electrons originate from the SEM’s electron beam and are reflected by the target material.
(iii) The X-rays emitted from the material can be used to determine the chemical composition of the target material’s outer layer.
(iv) All of the above statements are correct.

Answer 43

(iii) The X-rays emitted from the material can be used to determine the chemical composition of the target material’s outer layer.

Question 44

x) In the context of geometric inspection using a co-ordinate measuring machine (CMM) equipped with a kinematic resistive touch trigger probe, which touch probe property has an impact on the accuracy of a measurement?
(i) Length of the touch probe’s stem.
(ii) Hardness of the stylus ball.
(iii) Velocity with which the touch probe approaches the part to be measured.
(iv) All of the above.

Answer 44

(iv) All of the above.

Question 45

The following results are given in the format:
440 HV 20 / 30
x HV y / z

What does each letter represent?

Answer 45

x = Hardness Number
HV = Hardness Scale
y = Load applied in kg
z = Time the load was applied

Question 46

Two Rockwell hardness tests are conducted giving the following results:

65 HRC
85 HRB

What do they mean?

Answer 46

HRC = Rockwell Cone Scale
HRB = Rockwell Ball Scale

Question 47

Brinell, Rockwell and Vickers hardness testing. What do each measure and how do they measure it?

Answer 47

Brinell: Measures the size of the indentation which is made by a ball that is pressed in with x force for x time

Vickers: Measures the size of the indentation which is made by a pyramid pressed in with x force for x time

Rockwell: Measures the depth of the indentation which is made by a diamond cone (or sometimes ball)

Question 48

An electron beam is fired at the sample. What are the two interactions that will happen?

An image can be formed as a result. Which surfaces will appear brighter and why? And where in relation to the detector will these surfaces be?

Answer 48

Secondary electrons will be ejected from the sample due to in-elastic scattering. They will be low energy.

Back-scattered electrons originate from the beam and are reflected from the sample due to elastic scattering. They will be high energy.

Surface’s that are more inclined (towards the detector) will have more electrons that reach the detector. This in-turn creates a brighter surface on the image.

Just as a note: If you use multiple detectors then you can find that some surfaces are opposite each other as one detector detects loads of electrons, whilst the detector on the other side doesn’t.

Question 49

Explain how each of the following are obtained?

Maximum peak-to-valley height Rt
Mean peak-to-valley height Rz
Arithmetic mean roughness Ra

Answer 49

Rt is the difference between the highest peak and the lowest valley. I.e. the range.

Rz you split the data into 5 equal segments. Find the Rt in each segment (i.e. highest peak - lowest valley). Then add them all together and divide by 5 giving you the mean peak to valley height.

Ra you find the area underneath the curve (integrate between value and 0) and the value will = the arithmetic mean which can be plotted as a straight line (green rectangle).