The ceremsite sand is made from calcined bauxite by smelting and blowing process. So it’s also called fused bauxite beads. The crushing resistance of Fused Bauxite Beads sand directly affects the strength and durability of foundry sand.
The raw foundry sand is easily broken during the process of mixing, molding, pouring, falling sand cleaning, and recycling. That would make particles smaller than the origin and out of shape. It leads to a decline in the performance of the molding sand.
Commonly, the effect on sand performance including:
Lower strength caused by a finer particle (even powder)
Consumption of binder increasing.
Gas generation increasing.
Lower air permeability.
In addition, the broken and thinned raw sand causes dust pollution in the production environment. At the same time causes more raw sand consumption after dust removal and discharge. So it’s important to control the crushing rate of raw sand in the casting process. And it’s a good way to adopting raw sand with high particle strength and low crushing rate. The anti-crushing ability become a key factor to check core sand quality. Fused Bauxite beads have the advantage to meet that requirement.
The detection of crushing resistance of raw sand often adopts static pressure method and impact, pressurized friction, etc. However, most of the result evaluation methods are to detect the change of the raw sand particles before and after the comparison test (such as the average fineness) to form a reference comparison result.
In Haixu’s laboratory, we conducted strength comparison tests on several common raw foundry sands in ceramic grinding equipment. The raw foundry sands participating in the test include Fused bauxite beads, sintered ceramic sand, silica sand, chromite sand, and Japanese CB sand. The tested product specification is 50 mesh.
The test selects the particle size after 3 grinding time periods as the basis for comparison:
| Sand Type | Remaining Ratio after passing 50 mesh Sieve (%) | ||
| 1st test（15 min）after grinding | 2nd test（15 min） after grinding | 3rd test（15 min） after grinding | |
| Ceramsite sand (Fused Bauxite Sand) | 86.15 | 67.74 | 48.83 |
| Sintered Ceramic Sand | 80.10 | 64.20 | 47.08 |
| Silica Sand | 24.81 | 3.90 | 0.13 |
| Chromite Sand | 8.06 | 0.15 | 0.02 |
| CB Sand(Cerabeads From Japan) | 77.36 | 51.67 | 32.05 |
The results show that the crushing resistance of various foundry sands is not the same. Among them, the strength of Fused bauxite beads, sintered ceramic sand, and CB sand is much higher than that of silica sand and chromite sand. Fused bauxite beads has the strongest resistance to crushing. Therefore, it has obvious advantages as durable foundry sand.