Types of Pattern Part - 2.

 

• In casting, a pattern is a model of the object that has to be cast — it’s used to form the mold cavity into which molten metal is poured.
• Different types of patterns are used depending on the shape, size, complexity, and quantity of the casting required.

6. Gated Pattern:

Description:

A gated pattern includes multiple patterns connected by a gating system (runner and gate). This allows multiple castings to be made in one mold.

Used for:

Mass production of small castings.

Advantages:

Saves time and material.

Uniformity in production.

Disadvantages:

Complex mold preparation.

Example:

Small mechanical parts like bolts, nuts, and valves.

Gated Pattern

7. Sweep Pattern:

Description:

A wooden board (sweep) of the required cross-section is rotated around a central axis to form the mold cavity — used for symmetrical shapes.

Used for:

Large symmetrical castings (like cylindrical shapes).

Advantages:

Economical for large parts.

Reduces pattern cost.

Disadvantages:

Only suitable for symmetrical shapes.

Example:

Columns, large pipes, bells.

Sweep Pattern

8. Skeleton Pattern:

Description:

A framework pattern that represents the outline of the casting. The mold is formed by filling and shaping sand within the frame.

Used for:

Large castings with simple shapes where solid pattern would be too heavy.

Advantages:

Light and cheap.

Suitable for large jobs.

Disadvantages:

Needs skilled labor.

Time-consuming.

Example:

Large tanks, pipe bends, etc.

Skeleton Pattern

9. Shell Pattern:

Description:

Made in two halves of thin metal shell, used for shell molding process.

Used for:

Precision casting.

Advantages:

Smooth surface finish.

High accuracy.

Disadvantages:

Expensive.

Example:

Automobile engine parts, turbine blades.

Shell Pattern

10. Segmental Pattern:

Description:

A part of a pattern (segment) is used repeatedly to form the entire mold cavity.

Used for:

Large circular castings.

Advantages:

Reduces cost of making large full patterns.

Simple and efficient for large round shapes.

Example:

Wheels, large pulleys.

Segmental Pattern