The abrasive grains in a grinding wheel are its cutting points.
These grains come in many materials, shapes and sizes.
Most grains come in a variety of shapes which govern their
specific gravity and their cutting performance.
Typical types of grit:
| Aluminium Oxide
- Regular Brown:
- Tough form of aluminium oxide.
- 96% pure. Hardness around 18.5 GPa.
- Toughness imparted by metal oxides.
- For grinding high tensile strength materials, as well
as rough grinding, deburring, snagging, cutting and fettling
of low-alloy, ferrous materials.
- High friability.
- 99% pure. Hardness around 19.5 GPa.
- Friability imparts high speed and cool cutting grinding
characteristics, making it suitable for grinding hardened
and high alloy steels up to 62 Rc.
- Slightly less friable than white but a little tougher
- pink in colour due to the addition of metal oxides.
- 99% pure. Hardness around 19.0 GPa Knoop.
- Can be used in similar applications to WA and in particular
highly alloyed tool steels
| Silicon Carbide
- Harder than aluminium oxide at 24 GPa but more brittle.
- Used when grinding low tensile materials like cast iron,
non-ferrous and non-metallic.
- preferred by carbide tool grinders.
- Zirconia complex.
- 16 GPa.
- A tough abrasive which has good thermal stability at grinding
- Tends to be used in steel mills and foundries.
- A unique microstructure imparts good durability and high stock-removal
- The combination of hardness and toughness endows this type
of grain with the ability to cut both ferrous and non-ferrous