TYPES OF PATTERNS

TYPES OF PATTERNS:-
Various types of patterns depends on - Complexity of the job
- No of castings required
- Moulding procedure adopted
(a) 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 (Figure 3)
(b) 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
(c) Gated pattern – Gating and runner system are integrated with the pattern
Improves productivity
(d) 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
(e) 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
(f) Loose piece pattern – Withdrawing of the pattern from the mould is difficult
Useful for highly skilled job
Expensive
(g) Follow board pattern – Used for structurally weak portions
Bottom board is modified as follow board
(h) Sweep pattern – Useful for axi-symmetrical and prismatic shape
Suitable for large scale production
(i) Skeleton pattern – Stripes of wood are used for building final pattern
Suitable for large casting