Sand Casting Defect And Causes Analysis-Mold Material Factor

May. 10,2022

Matson Metal supplies a lot casting parts, like pump parts, valve parts, impellers etc. 
We have a lot experience in OEM Casting Service, including sand casting, investment casting etc. 
we meet quite a lot of problems and solved them more. 
Now let's continue our Casting sharing. and exchange experience between foundries.

1.Run out
Run out is when liquid metal leaks out of the mold, leading to an incomplete or missing casting.
A faulty mold or flask is responsible for run out.
Prevention of run out and incomplete castings
To prevent this casting defect, design the casting mold with precision. Inspect and replace any defective molds before casting.
High temperatures can lead to excess wear and tear of the mold. Use quality raw materials for your mold that can resist high temperatures.

2. Swells
Swells are an enlargement of the casting. Swells typically take on the shape of a slight, smooth bulge on the vertical face of castings.
Causes and prevention of swells
Swell is usually caused by improper or soft ramming of the mold or a low strength mold.
Molds should be built to withstand liquid metal pressure. Otherwise, the mold wall may give way or move back, causing swelling.
Using a strong, properly rammed mold prevents swells.

3. Drops
Drops occur when pieces of sand fall into metal casting when it’s still liquid. Drops appear as an irregularly shaped projection on the cope (top) surface of a casting.
Causes and prevention of drops
Four potential causes for drops and their preventions include:
  • Low sand strength: Use sand of a higher strength if this your culprit
  • Soft ramming: Provide harder ramming
  • Insufficient fluxing of molten metal: Properly fluxing molten metal removes impurities
  • Insufficient reinforcement of sand projections in the cope: Reinforce sand projections using nails or gaggers to fix this issue.