HA Specialty Sands
The term “Specialty Sand” covers all industrial minerals (except quartz sand) commonly used in foundries as molding material for the manufacture of cores and molds.
Specialty sands include natural mineral sands, sintering and melting products produced in granular form or turned into granular form by breaking, grinding, and grading processes, or inorganic mineral sands produced by other physical-chemical methods.
Specialty sands differ from quartz sand, particularly as regards their significantly lower thermal expansion behavior within the temperature range of 20 – 600°C, their heat conductivity, refractoriness, and other physical characteristics.
Specialty sands are used instead of quartz sand for core making and mold making because they are characterized by better physical-chemical properties. The main difference between HA-International’s Specialty sands and silica sand is the significantly lower coefficient of linear expansion and significantly lower thermal expansion behavior during the casting process.
Many years of experience have shown that the use of Specialty sands depends on the complexity of the respective casting, the metal used for the casting, the susceptibility to veining, the casting temperature, and the binder system.
Strengths of HA Specialty Sands
In consideration of the casting properties to be achieved, the individual advantages of a Specialty sand can be used to:
- Avoid sand expansion defects, especially finning/veining
- Avoid the addition of gas-forming ingredients
- Avoid metal penetration
- Increase the flowability of the sand
- Avoid a mold-metal interface reaction
- Control the formation of microstructure
- Produce thin-walled castings