20 Green Sand Casting Defects and Their Suggested Remedies

S.no

Name of Casting Defect

Probable Causes

Suggested Remedies

1

Blow holes

• Excessive moisture content in molding sand.

• Rust and moisture on chills

• Cores not sufficiently baked.

• Excessive use of organic binders.

• Molds not adequately vented.

• Molds not adequately vented.

• Molds rammed very hard.

• Control of moisture content.

• Use of rust free chills, chaplet and clean inserts.

• Bake cores properly.

• Ram the mold less hard.

• Provide adequate venting in mold and cores.

2

​Shrinkage

• ​Faulty gating and risering system.

• Improper chilling.

• ​Ensure proper directional solidification by modifying gating, risering and chilling.

3

​Porosity

• ​High pouring temperatures.

• Gas dissolved in metal charge.

• Less flux used.

• Molten metal not properly degassed.

• Slow solidification of casting.

• High moisture and low permeability.

• ​Regulate pouring temperature.

• Control metal composition.

• Increase flux proportions.

• Ensure effective degassing.

• Modify gating and risering.

• Reduce moisture and increase the permeability of mold.

4

​Misruns

• ​Lack of fluidity ill molten metal.

• Faulty design.

• Faulty gating.

• ​Adjust proper pouring temperature.

• Modify design.

• Modify gating system.

5

​Hot Tears

• ​Lack of collapsibility of core.

• Lack of collapsibility of mold.

• Faulty design.

• Hard ramming of mold.

• ​Improves collapsibility of core and mold.

• Modify casting design.

6

​Mental penetration

• ​Large grain size and used.

• Soft ramming of mold.

• Molding sand or core has low strength.

• ​Use sand having finer grain size.

• Provide hard ramming.

• Suitably adjust pouring temperature.

7

​Cold shuts

• ​Lack of fluidity in molten metal.

• Faulty design.

• Faulty gating.

• ​Adjust proper pouring metal.

• Modify design.

• Modify gating system.

8

Cuts and washes

• ​Low strength of mold and core.

• Lack of binders in facing and core stand.

• Faulty gating.

• Improve mold and core strength.

• Add more binders to facing and core sand.

• Improve gating.

9

Inclusions

• ​Faulty gating.

• Faulty pouring.

• Inferior molding or core sand.

• Soft ramming of mold.

• Rough handling of mold and core.

• Modify gating system.

• Improve pouring to minimize turbulence.

• Use of superior sand of good strength. Provide hard, ramming.

10

Fusion

• ​Low refractoriness in molding sand.

• Faulty gating.

• Too high pouring temperature of the metal.

• Pouring facing sand.

• ​Improve refractoriness of sand.

• Modify gating system.

• Use Lower pouring temperature.

• Improve the quality of facing sand.