Tag Archives: grinding

The DNA of a Grinding Wheel

A grinding wheel is a resin bonded abrasive composed of abrasive grains which are held tightly together by a bonding agent and reinforced with a woven material. The main function of a grinding wheel is to remove material from a workpiece in an abrasive action with each grain acting as a cutting tool.

Abrasive grains are particles of man-made abrasive compounds. Most manufacturers use recycled grains, United Abrasives uses high quality virgin grains that are made to exacting specifications. The chemical structure of the grains determines the shape, sharpness, hardness and friability of the abrasive. Typical grains are:

Aluminum Oxide

  • A tough grain used for cutting metals and without excessive fracturing

Silicon Carbide

  • A hard and sharp abrasive used on concrete


  • A fine, dense crystalline grain that is used for rugged stock removal

Ceramic Aluminum Oxide

  • Two times tougher than standard aluminum oxide

The resinoid bonding agent that holds the grains together determines the
resistance of the wheel.

United Abrasives uses multiple layers of long stranded fiberglass as the woven material to form a strong reinforcement layer that allows the wheel to be used at maximum RPM and withstand lateral pressure applied during use.

These three components are measured and combined and then pressed using an automated process during manufacture to form a grinding wheel.

United Abrasives’ labels are incorporated into the process and remain intact throughout the life of the wheel. For a quick overview on labeling, check out our post on How to Read a Grinding Wheel Label.

How to Read a Grinding Wheel Label

Below is an example of a label that is found on United Abrasive grinding wheels with all pertinent information a user needs to operate the wheel.

Section A:

  • “A24R-BF”
  • This is the marking system used to identify wheel type.
  • “A” – primary grain used to make the wheel, A= Aluminum Oxide
  • “24” – size of the abrasive grain
  • “R”- hardness of the bond, R is medium
  • “BF”- type of bond used, BF is Resinoid Reinforced

Section B:

  • “General Purpose Grinding On All Ferrous Metal”
  • This is a general description of the wheel.

Section C:

  • “4-1/2 x 1/4”
  • This is simply the size of the wheel in inches.
  • “4-1/2” is the diameter
  • “1/4” is the thickness of the grinding wheel.

Section D:

  • Type 27- wheel configuration
  • 7/8 – arbor size
  • #20063- part number

Section E:

  • Grind- short application description

Section F:

  • Each wheel will display a tool icon for easy selection

Section G:

  • 13,300- Maximum RPM

Bar code and Safety Information is included on every wheel in the lower left hand corner.

Want even more information on grinding wheels and how they work? Check out our article on The DNA of a Grinding Wheel.

Why is it important to use a backing pad with sanding discs?

Using a backing pad with sanding discs properly allows for airflow behind the sanding disc which substantially increases the life of the disc from 30% to 50%. This increased airflow additionally allows for debris to flow out improving contact and sanding effectiveness.

Backing Pad
United Abrasive Backing Pad
Fiber Discs
We recommend United Abrasives, 3A Aluminum Oxide Fiber Discs