Manufacturing Techniques Flashcards

1
Q

Name 2 single use/disposable casting techniques

A

sand casting
investment casting

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2
Q

Name some casting defects

A

Liquid metals containing gas cause porous end products
metal can contain oxides
misruns/cold shuts - when metal solidifies before mould is full

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3
Q

Why is sand casting used

A

low cost
versatile
small upper limit in terms of size and weight
can cast complex shapes
short lead time
mould is cheap to make from wax, wood or plastic pattern

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4
Q

Common problems in sand casting

A

erosion - metal can be poured in too fast and sand can end up in the cast
penetrations - if molten material is too viscous it can flow into voids of the mould
rough surface and relatively high levels or porosity an low dimensional accuracy

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5
Q

applications of sand casting and main material used

A

cylinder heads
landing gear
mainly used with alloys

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6
Q

batch size of investment casting

A

10-10,000

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7
Q

benefits of investment casting

A

good surface finish
can produce complex shapes
no parting line
can be used with almost any metal

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8
Q

drawbacks of investment casting

A

expensive pattern and mould
high labour costs
size limitations
high lead time
single use
slurry build up in moulds

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9
Q

Name 4 permanent casting methods

A

pressure casting
slush casting
die casting
centrifuge casting

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10
Q

pressure casting advantages, drawbacks and minimum batch size

A

clean finish, no oxidation
expensive, long set up time
minimum batch size of 1000

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11
Q

slush casting benefits and drawbacks

A

hollow cast, good external detail
wall thickness can vary

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12
Q

what are the 2 types of die casting

A

hot chamber - lower melting point, non-corrosive metals
cold chamber - metal is melted separately, high melting point & corrosive alloys

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13
Q

die casting advantages, drawbacks and minimum batch size

A

fast cycle times, thin sections
expensive equipment, small components produced (under 10kg)
minimum batch size of 10,000

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14
Q

2 types of centrifugal casting

A

true centrifugal and semi centrifugal

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15
Q

continuous casting advantages and drawbacks

A

very high volume
very basic shapes
only uses steel
post processing required since shapes are so basic

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16
Q

continuous casting shapes

A

bloom
billet
rounds

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17
Q

why are fluxes added to moulds

A

protect steel from oxidation

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18
Q

defects of continuous casting

A

longitudinal crack
sub-surface cracks
thermal shrinking
sticker breakouts

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19
Q

common applications of powder metallurgy

A

oil impregnated bearings
cutting tools
metal filters

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20
Q

common powder metallurgy materials

A

iron, copper, tin, nickel, titanium

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21
Q

limitations of powder metallurgy

A

typically lower strength
restricted to relatively small, light parts
expensive equipment

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22
Q

what is extrusion used to manufacture

A

railings, sliding doors, window frames, tubing, brackets, gears, hangers

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23
Q

materials used for extrusion

A

copper, aluminium, steel and lead

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24
Q

defects of extrusion

A

cracking
centre cracking
piping

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25
Q

what is punching used for

A

improve edge quality or create holes in sheet metal

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26
Q

bending applications

A

car bodies, paper clips

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27
Q

what is spring back

A

the material trying to return to its original shape so will straighten a bit once it has been bent

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28
Q

what shapes are made with extrusion

A

pipes, rods, pellets

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29
Q

thermoplastic mould temperature

A

90

30
Q

thermoset mould temperature

A

200

31
Q

welding process

A

permanent joining of two materials, usually by coalescence - bonding of the molecules of both metals

32
Q

what are tac welds used for

A

small welds to hold the join at the same angle before a full weld is carried out

33
Q

what is the fusion zone

A

the area that has been melted and solidified

34
Q

what is the heat affected zone

A

next to the fusion zone where there are changes in the microstructure but doesn’t melt

35
Q

forms of flux

A

powder, paste, coated filler rod

36
Q

flux function

A

produces gas shield, chemically cleans base metal and removes oxides, removes slag

37
Q

advantages of welding

A

extremely strong joint
distributed force
light weight joint

38
Q

limitations of welding

A

high energy requirements
limited to certain metals
similar metals must be used
permanent joints
residual stresses and distorsion
HAZ
expensive

39
Q

most common resistance welding process

A

resistance spot welding

40
Q

resistance welding advantages and limitations

A

no electrons required, no flux, easy and fast
complex and expensive equipment, electrode wear

41
Q

resistance welding applications

A

sheet metal fabrications, automotive body assembly

42
Q

diffusion welding advantages and application

A

can join different metals
titanium welding in aerospace

43
Q

brazing filler metal melting point

A

> 450 degrees celcius

44
Q

does brazing require a flux

A

yes - to prevent oxidation and clean base metal

45
Q

how is filler metal drawn into gap

A

capillary action - uniform gap and clean surfaces

46
Q

why is a welding agent used

A

reduce surface tension of the molten filler metal
enables it to spread across the surface of the base metal

47
Q

what is the most common material used for sheet metal forming

A

low carbon steel

48
Q

brazing disadvantages

A

not suitable for high temperature operating conditions
not as strong as welding (but still strong)
more sustainable to corrosion
tighter part tolerance required to promote capillary action

49
Q

how can you improve brazing joint strength

A

increase the contact area

50
Q

what is the filler metal melting temperature

A

<450 degrees celcius

51
Q

advantages, disadvantages and applications of soldering

A

cheap, quick, no HAZ, no distortion
limited joint strength, low temp applications
electronics, plumbing, automotive radiators

52
Q

name mechanical fasteners

A

stapling
seaming
crimping
snap in fasteners

53
Q

advantages and considerations of mechanical fasteners

A

easy to manufacture, easy to assemble and disassemble, movable joints, low cost
temporary joint, what materials are being joined, weight limitations, cost, appearance, dimensions

54
Q

adhesives industries

A

aerospace, automotive, home appliances, building products

55
Q

adhesive advantages and limitations

A

strong sealed bonds, distributed loads, thin components, low temperatures >200, no distortion, corrosion resistant
limited range of temps, long bonding time, surface prep vital

56
Q

what is subtractive manufacturing

A

parts made by removing material by chipping away from a bulk

57
Q

additive manufacturing

A

parts made from small building blocks e.g. inkjet printing

58
Q

advantages and disadvantages of additive manufacturing

A

more efficient energy use, waste reduced, huge design freedom
slow production, expensive

59
Q

inkjet printing advantages and disadvantages

A

stencil can be reused, stencil defines final print
contamination from earlier prints, incomplete ink transfer, one ink at a time

60
Q

what is the rake angle

A

angle of the cutting tool to the vertical

61
Q

what is the relief angle

A

the angle of the cutting tool to the horizontal

62
Q

up milling description

A

feed direction is traveling in the opposite direction to the tool direction

63
Q

advantages and disadvantages of up milling

A

backlash isn’t an issue
surface finish is impared, suited for older machines

64
Q

down milling advantages

A

better surface finish, better for modern machines

65
Q

which teeth go into a material first when broaching

A

roughing teeth then finishing teeth

66
Q

abrasive machining advantages and applications

A

high dimensional accuracy, excellent surface finish, can be applied to hard, brittle materials
ball bearings, pistons, valves, gears

67
Q

most common abrasive machining process

A

grinding

68
Q

what material does honing use

A

abrasive stones

69
Q

what material does lapping use

A

leather

70
Q
A