Defect Prevention

Penetrations occur in all cast parts that are produced with the sand molding method, regardless of the material. A number of measures have proven effective in the prevention of penetration and the most important ones are listed below:

  • Using finer sands or refining the grain size of the sand in the return sand through the inflow of fine-grained (core) sands. Adding additives to core sands
  • Increasing the additions that form lustrous carbon. The carbon softens under the effect of the casting heat and forms a protective film; the wettability is reduced
  • Increasing the proportions of binder and sediment, reducing the compactibility of the mold material system, which causes an increase of the sand's flowability and enables better compaction
  • Coating at least the mold and core components that are at risk; this significantly reduces the porous space immediately at the surface of the mold/core
  • Avoiding surface-active elements in the chemical composition of the material as far as possible, for example phosphorous and lead
  • Reducing the metallostatic pressure and improving the gating system to the effect that casting bursts and strong overheating of the mold and core components are prevented
  • Reducing the casting temperature
  • Using suitable coatings