Grinding Wheels – Types, Purposes and Uses

Grinding wheels are discs that contain abrasive particles and grains that have been bonded together to form a wheel shape. Although the disc format is the most common shape, they can also be made in the shape of cones or cups.

Grinding wheels are attached to grinders or saws and rotated at high speeds for a variety of tasks. The abrasive grit and grains in the wheel are able to grind or cut through hard materials such as metal or steel. The abrasive grains are bonded together by either organic or inorganic substances.

Inorganic grinding wheels are fitted in a furnace and have a hard yet brittle structure that holds its form during precision cutting. These wheels usually require dressing before use to straighten the wheel or to form it into a desired shape.

Organic grinding wheels are cured at low temperatures, are shock resistant and do not require dressing. They are commonly used for cutting or grinding work that does not need to be precise.

They are categorised according to characteristics such as grit size, the bonding used, the abrasive material, the grade of the grinding wheel and the wheel's structure.

 In general, six of them are commonly used:

Type 1 – Straight

Type 2 – Cylinder

Type 4 – Tapered

Type 6 – Straight cup

Type 12 – Dish

Type 13 – Saucer

Straight grinding wheels are usually used in bench grinders

Cylinder grinding wheels are used in horizontal or vertical spindle grinders to make flat surfaces

Tapered grinding wheels are wider in the centre with a surface that tapers outwards. These wheels are used to grind gear teeth or threads

Straight cup grinding wheels are fitted to cutter machines and used to sharpen tools or to make flat surfaces

Dish grinding wheels are thin with a flat centre that is raised outwards on the edge. These wheels are commonly used to cut openings such as slots

Saucer grinding wheels have a straight edge section and are used for twist mills and grinding cutters

Handheld tools and standalone machinery typically use abrasive wheels. They include:

Angle grinders – also known as disc grinders or side grinders, – used to cut or polish hard materials

Belt grinders – mounted table top grinders with two different types of grinding wheels on each side, which can sharpen tools and are used for roughing or finishing

Cylindrical grinders – used to shape the exterior of rods, tubes or bearing races

Jig grinders – heavy machines used for complex grinding and cutting work

Table saws – sometimes called bench saws – are used for cutting wood

Chop saws – handheld tools used to make straight cuts in wood

Petrol cut-off saws – handheld tools used to cut concrete, steel, stone, asphalt and other materials

When choosing a grinding wheel there are a range of factors that need to be taken into consideration.

Operators must take the following points into account:

The nature of the material being ground

How involved the task is

What the required finish is

The level of accuracy required

The contact area

The speed of the wheel

If coolant is to be used

The power of the machine or spindle to be used

Severe injuries or even death can occur if the wrong wheel is used for a task. Not only is the operator at risk but so are any persons in the near vicinity.

Injuries can be caused as a result of flying debris caused by abrasive particles, metal or wood fragments or broken pieces of the wheel. Loose clothing or long hair can be caught up the wheel to cause what is known as drawing-in injuries.

The dust, fumes and particles emitted by the work itself can be hazardous to the lungs and respiratory system. Over time, the vibrations and the noise that they emit can cause both nerve damage and hearing loss.