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Types of Abrasive Grains | Aluminum Oxide, Silicon Carbide and Diamond Explained
About Abrasive Grains
Abrasive grains are high-hardness granular or powdered materials that serve as the main cutting edges during the grinding of workpieces.
When mixed with a bonding agent, shaped, and sintered, they become a "grinding stone."
Abrasives are classified into three types: 1) Alumina-based (Aluminum Oxide), 2) Silicon-based (Silicon Carbide), and 3) Superabrasive (Diamond).
| Element | Conventional Grinding Stone | Rubber Grinding Stone |
|---|---|---|
| Abrasive grains | A, WA, C, GC, Ceramic, Diamond, etc. | |
| Bonding agent | Resinoid, Vitrified, Electroplated, Metal, etc. | Rubber |
| Pores | Yes | No (self-sharpening action removes swarf) |
Main Types of Abrasive Grains
| Category | Symbol | Type | Characteristics |
|---|---|---|---|
| Alumina-based | A | Brown Alumina Abrasive | Mainly composed of corundum crystals with titanium oxide in solid solution, giving it a brown color. Slightly softer than other abrasives but very tough, suitable for free grinding (double-ended grinders) and general copper grinding. |
| WA | White Alumina Abrasive | White in color with over 99% alumina purity and minimal impurities. Harder than A but less tough, so the grains micro-fracture during use, maintaining sharpness, making it suitable for grinding relatively hard materials such as alloyed, tool, or hardened copper. | |
| PA | Pink Alumina Abrasive | Refined by the Bayer process with added chromium oxide and, if necessary, titanium oxide, melted in an electric furnace, solidified, crushed, and granulated. Tougher and harder than WA, with excellent shape retention, long dressing cycles, and low grinding heat, suitable for hardened and tempered copper. | |
| HA | Fused Alumina Abrasive | Made from bauxite or Bayer-processed alumina, melted and solidified in an electric furnace, crushed and granulated. Mainly composed of single-crystal corundum. | |
| AE | Artificial Emery Abrasive | Alumina material from bauxite, melted and reduced in an electric furnace, solidified, crushed, and granulated. Composed mainly of corundum and mullite crystals, gray-black overall, high hardness with moderate toughness, with a unique crystalline structure providing self-sharpening. | |
| Z | Alumina-Zirconia Abrasive | Premium abrasive made by melting high-purity zirconia and alumina above 2500°C. Suitable for polishing copper, cast iron, heat-resistant copper, titanium, nickel alloys, aluminum alloys, titanium alloys, tungsten, etc. High hardness and toughness. | |
| Silicon-based | C | Alumina-Zirconia Abrasive | Black in color with over 95% silicon carbide purity. Harder than A or WA but less tough. Unsuitable for steel grinding due to rapid wear and dull finish, but suitable for aluminum alloys, copper alloys, non-ferrous metals, cast iron, hard brittle materials, and carbide grinding. |
| GC | Green Silicon Carbide Abrasive | Made from silica and coke reacted in an electric resistance furnace, crushed and granulated. Over 99% pure silicon carbide, high hardness but low toughness, suitable for grinding extremely hard materials such as carbide and special cast iron. | |
| Diamond-based | D | Carbon |
*WA-CM: Abrasive grains specially processed by our company
