Question

Patterns are usually coated with a parting agent to:

1. Increase strength of pattern
2. project pattern
3. Facilitate their removal from the moulds
4. Increase strength of mould

Answer 1

Correct Answer - Option 3 : Facilitate their removal from the moulds

Explanation:

Parting sand:

• The sand employed on the faces of the pattern before molding.
• Parting sand is used without the binder and moisture to keep the green sand not to stick to the pattern allow the parting surface the cope and drag to separate without clinging.
• Parting sand is clean clay free of silica.

Green sand:

• Green sand is a prepared mixture of silica sand with 18 to 30% clay and moisture content from 6 to 8%.
• Also known as tempered or natural sand.

Dry sand:

• Green sand that has been dried or baked in a suitable oven after making mold and cores is called dry sand
• It possesses more strength, rigidity, and thermal stability.

Loam sand:

• Loam sand is a mixture of sand and clay with water to a thin plastic paste.
• Patterns are not used for loam molding and shape is given to mold by sweeps.
• Loam sand consists of 50% silica and 50% clay.