Emery is also called brown fused alumina [BFA] or brown artificial corundum. It is made by melting refractory bauxite, iron filings, and carbon materials in an electric arc furnace. There are three smelting methods used –
- Fixed or stable furnace
- Dumping or tilting furnace
The third method needs large investment, so the first two are used at large. In comparison to a stable furnace, the dumping process has high Al2O3 content along with high TiO2 and low SiO2. Bisley is one of the most reliable industrial chemical suppliers for high-grade BFA material using either tilt or static furnace smelting methods. Buyers can achieve a range of sizing alternatives suitable in abrasive and refractory sectors.
How to distinguish brown fused alumina qualities?
BFA is a popular abrasive material that reveals the moderate hardness. It is applied widely and has a vast market share, so it becomes challenging to distinguish the BFA’s abrasive quality. You can distinguish BFA’s quality –
Check the particle size. If they are regular and uniform with hexagonal shape then the quality is good. Check the color. If the fixed furnace method is used in smelting, then the color is reddish-brown and will turn translucent when exposed to the sun. The BFA shows red and black color if the tilting method is used.
By its magnetic content
BFA contains magnetic materials. Good quality contains small amounts. Use a magnet and if more grains get attached then the magnetic compound is more, which can gravely impact its hardness. Few magnetic impurities mean alumina quality is better.
By ash content
The BFA production process uses water but many manufacturers ignore this to decrease the operation cost. Therefore, there is plenty of dust in the produced brown alumina oxide grits, which can badly impact sandblasting effect. Put some BFA samples in clear water. If the product contains plenty of ash there will be a white substance layer floating on the water surface. If the BFA is not polluted then the water will be clear, which means the quality is good.
By pressing and rubbing
Good quality BFA reveals the high hardness. Place a handful of BFA grit on white paper. Press and wipe with bare hands. If you see crushed particles then the hardness is insufficient and the quality is not good. Remember, a more wear-resistant BFA grit is better in hardness.
Understand BFA grit sizes & grades
F grains – The particle size is between 4 to 240 meshes. It is commonly applied for grinding as well as polishing workpieces and castings.
P grains – It needs different processing methods like water washing, pickling, air selection, etc. The size of the particle is 8 to 220 meshes. Generally, P grains are applied in the grinding of a high-precision workpiece.
W grains – It is a series of finely powdered BFA geniuses. The numbers from W1 to W63 are very fine particle sizes.
First grade BFA has 94.5% to 97% aluminum content, while secondary grade has 85% to 90%. Low aluminum content is equivalent to low hardness.
First grade BFA is used for water filtrations, sandblasting abrasives, and more, while the secondary grade is applied in grinding, sandblasting, polishing, rust-removal, anti-corrosion, emery cloth material, stone carving, and more.