This document discusses casting patterns. It begins by defining foundry or casting processes and the basic steps, which include pattern forming, core forming, mould preparation, pouring molten metal, cooling and solidification, and cleaning. Patterns are replicas of the part to be cast and prepare the mould cavity. Common pattern materials include wood, metal, and plastic. Pattern types include single piece, split, loose piece, match-plate, sweep, and gated patterns. Patterns include allowances for shrinkage, draft, machining, distortion, and rapping. Patterns are color coded to indicate surfaces and features like core prints and parting lines.

1. Casting Patterns
by
Dr. Saurabh Sangal
Assistant Professor
Mechanical Engineering
SRMS CET,Bareilly

2. Content
•Foundary or Casting Process
•Basic steps of casting
•Pattern
•Pattern materials
•Pattern types
•Pattern allowances
•Colour coding of patterns

3. Foundary or Casting Process
• Foundary is a collection of the necessary materials, tools
equipments to produce casting.
• Casting is a manufacturing process in which a liquid material is
usually poured into a mould, which contains a hollow cavity of
the desired shape, and then allowed to solidify.
• Casting is most often used for making complex shapes.
• Heavy equipment like machine tool beds, ships' propellers, etc.
can be cast easily in the required size

4. General terms
• Pattern: Replica of the desired part
• Mould- Container with a cavity within. Divided in two
halves: Cope and Drag.
• Gating system- Network of channels that deliver molten
metal to the cavity.

5. Basic steps in Casting
• Pattern forming
• Core Forming
• Mould preparation
• Melting of metal and pouring
• Cooling and solidification of metal
• Cleaning of casting and inspection

6. Pattern
• Pattern is the principal tool, a replica of the product to be
casted.
• A pattern preapres a mould cavity in which molten metal is
poured.
• Properly constructed patterns have finished and smooth
surface that reduces the casting defects and overall cost of
casting.

7. Pattern Materials
 Wood, Metal, Plastic, Polystyrene etc.
 Requirements:
 Easily shaped, worked, machined and joined
 Resistant to wear and corrosion
 Resistant to chemical action
 Dimensionally stable
 Easily available and economical

8. Pattern Types
 Single piece pattern
 Split pattern
 Loose Piece pattern
 Match-plate pattern
 Sweep pattern
 Gated pattern
 Shell pattern

9. Pattern Allowances
 When the cast solidifies, it shrinks at some limit due to metal shrinkage
property at the time of cooling. So to compensate for this, a pattern is made a
little bigger.
 These slight changes in the pattern dimensions are known as pattern
allowance.
 Shrinkage allowance
 Draft or taper allowance
 Machining or finish allowance
 Distortion or camber allowance
 Rapping allowance

10. Colour coding of pattern
Colour Indication
Black  Unfinished surface on casting
Red  Finished surface on casting
Yellow  Core prints
Black  Parting surface
yellow strips  Seats for loose piece

11. Thank You....