Question

Explain any four defects in casting and give remedies of it.

Answer 1

Casting Defects	Remedies
Shifts	By ensuring proper alignment of the pattern or die part, moulding boxes, correct mounting of patterns on pattern plates, and checking of flasks, locating pins, etc. before use.
Warpage	Is to produce large areas with wavy, corrugated construction, or add sufficient ribs or rib-like shapes, to provide equal cooling rates in all areas; a proper casting design can go a long way in reducing the warpage of the casting.
Swell	To avoid swells, the sand should be rammed properly and evenly.
Blowholes	To prevent blowholes, the moisture content in sand must be well adjusted, sand of proper grain size should be used, ramming should not be too hard and venting should be adequate.
Drop	The given factors are eliminated to avoid drop.
Porosity	Increase flux proportion, Ensure effective degassing, Reduce moisture and increase permeability
Shrinkage	Ensure proper directional solidification by modifying risering and chilling.
Misruns and cold shuts	Adjust proper pouring temperature, Modify design, Modify gating system.
Inclusions	Improve or modify gating and pouring, Use a superior sand, Provide harder ramming, Use proper flux
Hot Tears	Improve collapsibility, Modify design, Provide soft ramming
Cuts and Washes	Improve collapsibility, Modify design, Provided soft ramming
Metal Penetration	Use sand having finer grain size, Provide harder ramming, Increase the strength of sand, Adjust the proper pouring temperature,
Fusion	Improve refractoriness, Modify refractoriness, Use lower pouring temperature, Improve quality of facing sand
Shot metal	Use higher pouring temperature, Reduce sulphur content, Modify gating system.
Rat Tails or Buckles	Reduce mould hardness, Break continuity of large surface by grooving or depressions.
Hard Spots	Suitable change in the metal composition, Modify the casting design
Run outs	Improve moulding technique,Change the defective moulding boxes.
Crushes	Repairs or replace core boxes, Repairs or replace core prints, Proper setting of cores.