Types of Patterns in Casting Process
- Single piece pattern – Inexpensive and simplest one Single piece, Simple job, Useful for Small scale production Pattern will be entirely in the drag One surface is flat and at the parting line, Used for very small scale production.
- Split or two piece pattern – Used for intricate casting, Split along the parting line, Used where depth of job is too high, Aligned with dowel pins fitted to cope.
- Gated pattern – Gating and runner system are integrated with the pattern
- Cope and drag pattern – Similar to split pattern, For cope and drag, separately attached gating system to metal plate, Heavy and inconvenient for handling, Useful for Continuous production.
- Match plate pattern – Similar to cope and drag patterns with gating and risering system mounted on a single matching plate, Pattern and match plate are made up of metal (Al), Useful for small casting with high dimensional accuracy, Suitable for large scale production, Gating system is attached to the match plate, Expensive.
- Loose piece pattern – Withdrawing of the pattern from the mould is difficult, Useful for highly skilled job, Expensive.
- Follow board pattern – Used for structurally weak portions
Bottom board is modified as follow board.
- Sweep pattern – Useful for Axi-symmetrical and prismatic shape, Suitable for large scale production.
- Skeleton pattern – Stripes of wood are used for building final pattern, Suitable for large casting.
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