Engineering Materials and
Manufacturing Processes
Lesson 3C
,Patterns and Cores
Sand casting
the most widely used casting process
one of the few processes that can be used for
alloys with high melting temperatures
steels, nickel alloys, titanium alloys
versatile – huge range of size and volume of
production
Sand casting - pour molten metal into a sand mould,
allow the metal to solidify
break up the mould
remove the casting.
,The cavity in the sand mould
formed by packing sand around a pattern
a duplicate of the part to be cast
remove the pattern by
separate the mould into two halves.
The mould also contains the gating and riser system.
If the casting is to have internal surfaces
hollow parts or parts with holes
a core must be included in the mould.
, Patterns and Cores
Pattern—a full-sized model of the part
enlarged to compensate for shrinkage
and machining allowances in the
final casting.
Materials for making patterns
wood, plastics, metals.
Wood is a common pattern material
it is easily shaped.
Its drawbacks
tendency to warp
abrasion by the sand compacted around it
limiting the number of times it can be reused.
Manufacturing Processes
Lesson 3C
,Patterns and Cores
Sand casting
the most widely used casting process
one of the few processes that can be used for
alloys with high melting temperatures
steels, nickel alloys, titanium alloys
versatile – huge range of size and volume of
production
Sand casting - pour molten metal into a sand mould,
allow the metal to solidify
break up the mould
remove the casting.
,The cavity in the sand mould
formed by packing sand around a pattern
a duplicate of the part to be cast
remove the pattern by
separate the mould into two halves.
The mould also contains the gating and riser system.
If the casting is to have internal surfaces
hollow parts or parts with holes
a core must be included in the mould.
, Patterns and Cores
Pattern—a full-sized model of the part
enlarged to compensate for shrinkage
and machining allowances in the
final casting.
Materials for making patterns
wood, plastics, metals.
Wood is a common pattern material
it is easily shaped.
Its drawbacks
tendency to warp
abrasion by the sand compacted around it
limiting the number of times it can be reused.
