Types of Casting Pattern

Pattern 

In casting, a pattern is a replica of the object to be cast, used to prepare the cavity into which molten material will be poured during the casting process. Patterns used in sand casting may be of wood, plastics, or other materials.

Different types of patterns.

1. Single piece pattern -

It is the simplest type of pattern of all the other types. For making a mold, the pattern is accommodated either in cope or drag. 

2. Split Pattern -

 In this type, the patterns are divided into two parts along a parting plane to facilitate the extraction of the pattern out of the mold before the pouring of operation. For more complex operations the pattern is split into more parts.

3. Loose piece pattern -

 When a one-piece solid pattern has projections or backdrafts which lie above or below the parting plane, it is impossible to withdraw it from the mold. With such patterns, the projections are made with the help of loose pieces. One drawback of loose feces is that their shifting is possible during ramming.

4. Gated pattern - 

A gated pattern is simply one or more loose patterns having attached gates and runners. Because of their higher cost, these patterns are used for producing small castings in mass production systems and on molding machines.

5. Match plate Pattern - A match plate pattern is a split pattern having the cope and drags portions mounted on opposite sides of a plate (usually metallic), called the "match plate" that conforms to the contour of the parting surface.

The gates and runners are also mounted on the match plate, so that very little handwork is required. This results in higher productivity. This type of pattern is used for a large number of castings. Piston rings of I.C. engines are produced by this process.

6. Sweep Pattern - A sweep is a section or board (wooden) of proper contour that is rotated about one edge to shape mold cavities having shapes of rotational symmetry. This type of pattern is used when a casting of large size is to be produced in a short time. Large kettles of C.I. are made by sweep patterns.

7. Cope and Drag pattern - A cope and drag pattern is a split pattern having the cope and drag portions each mounted on separate match plates. These patterns  are used when in the production of large castings; the complete molds are  too heavy and unwieldy to be handled by a single worker.

8. Skeleton Pattern - For large castings having simple geometrical shapes, skeleton patterns are used. Just like sweep patterns, these are simple wooden frames that outline the shape of the part to be cast and are also used as guides by the molder in the hand shaping of the mold.
This type of pattern is also used in-pit or floor molding process.

9. Follow Board Pattern - A follow board is not a pattern but is a device (wooden board) used for various purposes.