casting

details casting types and their advantages and disadvantages

casting

metal solidifies in the mould

sand casting

disposable casting

investment casting

disposable casting - master die required to make wax pattern

pressure casting

permanent casting - molten metal forced upwards by pressure increase/vacuum

slush casting

permanent casting - metal into mould where shells forms on inside to desired thickness

die casting

permanent casting - molten metal injected into metal die under high pressure (hot chamber or cold chamber)

true centrifugal casting

molten metal poured into rotating mould - axis of rotation can be horizontal/vertical

semi-centrifugal casting

molten metal poured into rotating mould at central reservoir - MUST have rotational symmetry

centrifuging

molten metal poured into rotating mould but shape is offset from axis of rotation

sand casting advantages

cheap

variety of metals

no limit on size

complex shapes

short lead time

sand casting limitations

low dimensional accuracy

rough surface finish

holes

slow

sand casting applications

train wheels

engine crankshafts

turbine impellers

investment casting advantages

excellent surface finish

high dimensional accuracy

complex shapes

fast

investment casting limitations

expensive

size limited

significant lead time

holes

investment casting applications

gears

valves

aircraft engine components

knee replacements

porosity

tiny holes within a material.

pressure casting advantages

no oxidation

good mechanical properties

high dimensional accuracy

good surface finish

high material yield

pressure casting limitations

long

expensive

shape + size complexity is limited

pressure casting applications

high quality automotive items

slush casting advantages

hollow casts

efficient material use

good external detail

slush casting limitations

hollow casts ONLY

variable wall thickness throughout mould

slush casting applications

ornaments e.g.

candlesticks

latex

silicon props

die casting - hot chamber

gooseneck submerged in heated reservoir - low melting point

die casting - cold chamber

molten metal transferred to unheated chamber - high melting point

die casting advantages

fast

high dimensional accuracy

good surface finish

thin sections

good mechanical properties

die casting limitations

expensive

requires high quantity

small components only

die casting applications

wide variety of non-ferrous castings

true centrifugal casting advantages

no oxidation

high dimensional accuracy

strong exterior

large parts

true centrifugal casting limitations

inner surface MUST be cylindrical

MUST have rotational symmetry

expensive

true centrifugal casting applications

pipes

pressure vessels

bake drums

bushings and bearings

semi centrifugal casting advantages

stacks several moulds

complex shapes - more than true

semi centrifugal casting limitations

MUST have rotational symmetry

semi centrifugal casting applications

gear blanks

pulley sheaves

wheels

rotors for electric motors

centrifuging advantages

variety of intricate + thin walled shapes

no oxidation

strong parts

centrifuging limitations

small parts only

centrifuging applications

investment casting patterns