Characteristics of Silicon Carbide Abrasive
Silicon carbide is a synthetic mineral known for its extreme hardness and sharpness.
High Hardness: On the Mohs scale, it has a hardness of 9.5. This is harder than aluminum oxide (the other major abrasive) and second only to diamonds, CBN, and a few other exotic materials.
Extreme Brittleness (Friability): The crystals are very brittle and fracture easily. This might sound like a weakness, but it’s a key advantage. As the abrasive grains wear, they fracture to reveal new, sharp cutting edges. This property is called self-sharpening.
Excellent Thermal Conductivity: It conducts heat well, which helps dissipate the heat generated during grinding.
Primary Applications of Silicon Carbide Grinding Discs
| Material Category | Specific Examples | Why Silicon Carbide is a Good Choice |
|---|---|---|
| Non-Metallic, Hard & Brittle Materials | Glass, Ceramics, Porcelain Tiles, Stone, Marble, Granite | Its extreme hardness and sharpness are perfect for cutting and grinding these difficult materials. It cleanly shears the material rather than deforming it. |
| Soft Non-Ferrous Metals | Aluminum, Copper, Brass, Bronze, Lead | The sharp grains cut these soft, gummy metals efficiently without loading (clogging) the disc. Using a disc designed for steel on aluminum can be dangerous due to loading. |
| Rubber, Leather, Plastics | – | Used for deburring and smoothing these softer materials. |
| Titanium Alloys | – | Its sharpness and thermal conductivity help reduce the risk of “grinding burns” on heat-sensitive metals like titanium. |
| Hardened Steel & Cast Iron | Finishing welds on cast iron |
Why is Silicon Carbide Ideal for Certain Grinding Discs?
Because of its brittleness and sharpness, silicon carbide is not suitable for grinding high-tensile strength materials like steel. Instead, it excels at grinding materials that are:
Hard but with Low Tensile Strength (Hard and Brittle Materials): The sharp grains can easily penetrate and micro-chip these materials.
Soft and Ductile (but can clog other discs): Its sharpness and self-sharpening action help prevent the disc from becoming clogged.