The synthetic, spherical sand ‘MinSand’ is used to improve the standard mould material for cores and moulds and is a cost-effective alternative to zircon sand.
For a long time, the industry uses Bauxite in the production of shaped and unshaped products for the refractory industry. More recently companies developed an additional application; Bauxite in the foundry industry. The industry uses MinSand, produced from Bauxite, with all types of castings.
Production of beads
To obtain the spherical shaped grains/beads of MinSand, we blow air into a jet of liquid bauxite after fusing and super-cooling in an electric arc furnace. We classify the beads into different particle sizes by screening, some examples shown in table 1.
|Sieve||AFS 50||AFS 65||AFS 90|
Table 1: Typical weight percentage of several particle sizes of MinSand, other sizes available on request
Flowability, thermal & dimensional stability and core strength
The spherical shape of the sand-binder mixture produced with MinSand significantly improves the flowability compared with other mould materials available on the market. In addition, the rounded grain shape also creates strong binder bridges which result in the need for reduced binder additions when utilising MinSand. On top of that, you can reduce the binder additions for core and mould production with MinSand by about 40% compared to silica sand. We have several studies to prove this. Because of the low addition of binder resin, our customers utilise MinSand with any coating systems.
The heat resistance of a core and moulding sand plays a major role in the stainless steel and cast steel industry. These are particularly the industries where they achieve the highest casting temperatures. MinSand is suitable as a mould material for these types of casting. Mainly because it:
- is not prone to mould material-metal reactions
- has high refractoriness (sintering temperature > 1,950 °C)
- is resistant to metal penetration even in highly thermally stressed castings.
The heat resistance of MinSand is attributed to its high alumina content.
Benefits for MinSand in applications
Due to the very small linear expansion of MinSand, castings can be produced with a high level of accuracy. This is also a special advantage for the non-ferrous light metal castings in which intricate cores are produced. For example, our customers use a lattice consisting of MinSand in the production of water jacket cores for cylinder heads. They avoid tension cracks in the core due to the high strength. On top of that, the mould material is even suitable for thin-walled castings.
In the casting of grey and ductile iron, veining can often arise if using quartz sand, which often succumbs to quartz inversion. Therefore, to avoid this, you can use MinSand. MinSand is extremely stable and allows the casting of complex shapes without casting defects. Moreover, the moulding sand is an alternative to cold-box mixes with gas-forming additives which helps produce heavy metal castings without any metal penetration.
Conclusion MinSand use
The spherical shape of the sand-binder mixture produced with MinSand significantly improves the flowability compared with other moulded materials available on the market. Because of this MinSand is an excellent addition to special moulding sands for the foundry industry.
In addition, it also has:
- excellent refractoriness
- low linear thermal expansion
- high dimensional stability
- good gas permeability
- reduction in binder additions required
Finally, check our MinSand product page to reach the sales manager in your region.