Pattern 1.2

Pattern
 Replica of the desired product
 Has somehow different dimensions than the actual
part to be manufactured
 Used to form the mold cavity
1. Materials used
2. Types of patterns
3. Pattern Allowances

Pattern Materials
 Requirements:
1. Easily shaped, worked, machined and joined
2. Resistant to wear and corrosion
3. Resistant to chemical action
4. Dimensionally stable
5. Easily available and economical

Pattern Materials
2. Metal:
Used for large quantity production and for closer dimensional
tolerances
Longer life
Aluminum is mostly used.
Other metals: cast iron, brass etc.

Pattern Materials
3. Plastic:
Low weight, easier formability, smooth surfaces and durab
ility
Do not absorb moisture. So, dimensionally stable
Corrosion resistance

Pattern Materials
4. Polystyrene:
Changes to gaseous state on heating
Disposable Patterns. Hence, suitable for single casting.
When molten metal is poured into cavity, polystyrene transforms to
gaseous state.
Used mostly for small and complicated shaped castings.

Pattern Types
1.Single piece pattern:
Used for simple shaped & large castings.
Pattern and cavity produced by it are completely
in the lower flask (i.e. drag)
Causes difficulty in making the mold.

Pattern Types
2.Split pattern:
Split pattern models the part as
two separate pieces that meet along
the parting line of the mould
Two parts are aligned by Dowel pin.

Pattern Types
4. Match-plate pattern:
Similar to a split pattern, except that each half of the pattern is attached to
opposite sides of a single plate.
Match plate confirms the parting line
Ensures proper alignment of the mould cavities in the cope and drag and the
runner system can be included on the match plate.
Used for larger production quantities.
Ic Engines piston rings

Pattern Types
4. Cope-Drag pattern:
It is similar to split pattern
Each half of the pattern is attached to a separate plate and the mould halves
are made independently.
.Pattern is made in two halves and split along parting line
These two halves are known as cope and drag
There moulding done independently
After moulding they are assembled to form complete mould box
Often desirable for larger castings

Pattern Types
5. Gated pattern:
In this patters of gate and riser or runner are permanently attached to regular
pattern
They are used to manufacture multiple casting in on time
Each pattern is connected with common runner .
Suitable for pouring small castings and for mass production
It save labour and time

Pattern Types
1. As pre The name Pattern Contain One or more than one loose piece
2. Loose piece is used to make removal of pattern easy from mould box
3. loose pieces are attached to main body with the help of dowel pins or wire
4. First main pattern is drawn and then carefully loose pieces
5. Moulding with this pattern is expensive and require more skill
3.Loose Piece pattern

Pattern Types
• A sweep pattern is just a form made on a wooden board which sweeps the
shape of the casting into the sand all around the circumference. The sweep
pattern rotates about the post
• Once the mould is ready, sweeppatternand the post can beremoved
• Sweep pattern avoids the necessity of making a full, large circular and c
ostly3Dpattern
• Making sweep patterns save a lot of time and labour as compared to making a ful
l pattern
• A sweep pattern is preferred for producing large
• casting of circularsectionsand symmetricalshapes
Sweep pattern

Pattern 1.2

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Pattern 1.2