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What is draft allowance? How is it provided for patterns?It the
vertical faces of pattern are perpendicular to parting line, the
edges
of mould may damaged when the pattern is removed from the
sand.Hence the vertical faces are mode taper for easy removal of
pattern. Thisslight taper given on the vertical sides of pattern in
caused draftallowance.What are the common allowances provided on
pattern?
The various types of pattern allowances normally given
areShrinkage allowanceMachining or nish allowanceDraft or taper
allowanceDistortion or cam er allowance!apping or shake
allowanceWhat are the functions or riser?
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The main function of the riser is to supply e"cess molten metal
to thesolidifying casting ,It allows the escape of air.How pattern
di er from casting?#attern is slightly larger in si$e as compared
to the casting.#attern may e in two or three pieces where as a
casting is in one piece.What are the tests carried out to determine
the quality ofcasting?Destructive test%Tensile, Impact, Hardness
etc.&on Destructive%'isual, sound, magnetic particles, dye
penetration,ultrasonic etc.De ne foundry:( plant where the castings
are made is called a foundry.De ne casting:
The #rocess of producing metal parts y pouring molten metal in
to themould cavity of the re)uired shape and allowing the metal to
solidify. Thesolidi ed metal piece is called as casting.De ne
mould:Mould is the cavity of the re)uired casting made in wood,
metal orplastics.De ne pattern%
The Model of the re)uired casting made in wood, metal or
plastics.Name the various pattern materials:*ood + Teak wood, white
pine etc.Metal + cast iron, rass, aluminium etc.#laster#lastic
*a"What are the di erent types of patterns used in
foundries.Solid or single piece pattern, match plate pattern, split
pattern, sweeppattern, skeleton pattern, segmental pattern, loose
piece pattern, shellpattern.When do you made core or! what is
function of core in mouldingsand?
To provide a hollow surface or recess on the casting, the core
is made.What is core print and what is its purpose?( core print is
an e"tra pro ection on the pattern. It supports the core.What do
you understand "y core setting -
aring or heating the cores to o tain enough hardness is called
as coresetting.What are requirements of core sand#ermea ility,
refractoriness, strength collapsi ility, sta ility.#ention the
speci c advantages of $%& process/ive strength and hardness to
core#rocess cost is lessIt saves time on heatingIt can e stored for
long useWhat are the properties good moulding sand?
#orosity or permea ility, plasticity or 0owa ility, strength or
cohesiveness,adhesiveness,
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refractoriness, collapsi ility./reen sand, Dry sand, What are
the di erent types of moulding sand?Synthetic sand, 1oam sand,
Special sand, parting sand.Write the composition of good moulding
sand ./reen sand%It contains 2 to 34 water and 52 to 674 clay.1oam
Sand%1oam sand is a mi"ture of ne sands, ne refractoriness, clay,
graphite
er andwater. It contains more clay 82749What are the uses of
runner and riser?'unner:It is used to make a sprue a hole in the
cope.It receives the molten metal from the pouring asin and passes
to thecavity.'iser:It supplies e"cess molten metal to the
solidifying casting.It allows the escape of air.What are
chaplets?Some times it is not possi le to provide su:cient support
for a core in themould eing poured, if the cores are igger in si$e.
In such cases the coreis supported with rigid metal pieces called
chaplets.What are the di erent types of furnaces used for
casting?
upola furnace, open hearth furnace, cruci le furnace, pot
furnace,;lectric furnace.
What is need for providing chills in casting? The chills are
used to provide directional solidi cation or to increase therate of
solidi cation where the higher hardness re)uired.Name four di erent
casting defects.Shifts < Two halves mismatching or castingHot
tear < Internal or e"ternal cracks=ins < Thin pro ection of
parting lineInclusions < =oreign material present in casting
