| Core Sand Additives | Antrapex 


Developments in core-making technology and binding agents have resulted in an increase in specific strength.
Aside from a low content (i.e. consumption level) of binding composition in the core moulding material, there has
also been a raft of technological and economic advantages leading to the cost-effective achievement of the
required strength levels – such as improved shake-out and reclamation performance and a reduction in emissions
and gas-induced defects.

The attainment of smooth and defect-free component surfaces in the as-cast condition is a challenge that
foundrymen and their suppliers jointly face on a daily basis. Defect susceptibility is directly associated with the
alloying method, the casting parameters, i.e. temperature and speed, the complexity and structure of the casting,
the cores used and also the core and process-specific characteristics (hot strength, mouldability).

Veining (aka finning) constitutes a very frequent type of defect that occurs particularly in association with core-making
using chemically bonded moulding sands. Veining arises as a result of penetration of the molten metal into cracks on
the mould or core surface. The cracks are caused by the thermal stressing of the moulding material and progressive
quartz sand expansion with the associated step-change shifts that arise during the casting and solidification processes.