Ceramic Fused Alumina (CFA) for Lost Foam Casting is a premium, high-performance molding aggregate, often referred to by its common trade names like “Cerabeads” or “Spherical Ceramic Sand.”
What is Ceramic Fused Alumina (CFA)?
It is a synthetic, man-made spherical sand produced by melting high-purity alumina (Al₂O₃) in an electric arc furnace at temperatures above 2000°C and then blowing or spinning the molten material to form near-perfect spherical grains. It is then screened to specific grain size distributions (AFS grades).
| Chemical Analysis[%] | |
| Al2O3 | 70-73 |
| SiO2 | 8-20 |
| Fe2O3 | ≤3 |
| TiO2 | ≤3.5 |
| CaO | ≤0.45 |
| MgO | ≤0.35 |
| K2O | ≤0.33 |
| Na2O | ≤0.08 |
| Physical Properties | |
| Grain shape | Spherical Ball |
| Roundness | 90% |
| Refractoriness: | ＞1790℃ |
| Shape Coefficient | ≤1.1 |
| Thermal Expansion Ratio | 0.13%（Heated up for 10 min at 1000℃） |
| Thermal expansion coefficient | 6×10-6 /℃(20-1000℃) |
| Thermal conductivity | 0.698W/M.K(1200℃) |
| Specific Gravity:: | 1.95-2.05g/cm3 |
| Bulk density(LPD): | 3.4 g/cm3 |
| Color: | Black |
| AVAILABLE SIZES | |
| AFS25-35,AFS35-45,AFS45-55,AFS55-65,AFS60-70,AFS70-80,AFS95-110 | |
How Does Lost-Foam Casting Work?
Here is a look at the step-by-step process for lost-foam casting.
- First, the foam molds are prepared. These are in the shape of the intended finished product and they get filled through a gating system with passages that allow for precise design specs.
- Next, you bond the foam pattern or mold to the gating mechanism to make sure the alignment is spot on.
- Then you’ll apply dip paint, which, when dry, creates a ceramic coating on your mold, boosting its toughness, heat resistance, and ability to handle the high temperatures of the metal.
- Once this is done, you’ll place the mold and gating mechanism (which are now one piece) into a bucket, container, or vessel of dry sand. This holds your piece in place and keeps it in the right position during casting.
- After filling with sand, the container will go through vibration to make sure that the sand fully encompasses the module.
- This is when the molten metal gets poured into the mold. The heat of this makes the mold vaporize (sorcery!), leaving room for the metal to fill in and form.
- Finally, after the molds have cooled, they’ll go through cleaning and finishing. You can also recycle the sand.
Ceramic Fused Sand Applications Lost-Foam Casting
High-Value Ferrous Castings: Ductile iron, alloy iron, carbon steel, stainless steel, and high-alloy steel castings.
Complex & Thick-Sectioned Castings: Where gas evolution is massive and mold stability is critical.
Castings Prone to Expansion Defects: Where silica sand would cause veining.
High-Volume Production Lines: Where sand reclamation and consistency are economically vital.
Ceramic Fused Alumina is a premium, engineered sand that addresses the core challenges of Lost Foam Casting:
It provides exceptional permeability for gas venting.
It ensures dimensional accuracy through low expansion and high stability.
It offers long-term economic efficiency through superior reusability.