Learning about Grinding Wheels

Grinding wheels can be confusing. There are a lot of symbols and numbers and it is not always the easiest to remember what they all mean.
Using one of our Ernö branded grinding wheels we will break down the major components listed on our wheels in the sections below.

  1. These are the dimensions of the wheel
    a. 4-1/2” is the diameter
    b. ¼” is the thickness of the grinding wheel
    c. 7/8 is the arbor size of the grinding wheel                                                                                                                                                                                                                                                                                                                                      
  2. This section displays the maximum RPMS (revolutions per minute).
    a. This specific wheel has a maximum of 13,300 RPMS                                                                                                                                                                                                                                                                                                                  
  3. This is the main identifier to indicate what type of grinding wheel it is.
    a. “A” is the main grain component of wheel. In this case, aluminum oxide.
    b. “24” is the size of the abrasives grain contained in the grinding wheel
    c. “R” is the hardness of the wheels bond. Hardness ranges from A-Z (soft-hard). So for this wheel, R is medium hardness.                                                                                                                                                                                     
  4. Various safety symbols to advise safe practices in the use of the grinding wheel                                                                                                                                                                                                                                                                   
  5. This is indicate the material that the wheel is intended for use on. In this case, steel.                                                                                                                                                                                                                                                             
  6. This is the symbol for The Organization for the Safety of Abrasives, otherwise known as OSA. To qualify to apply this mark to products, members commit to certified quality management with documented processes and internal testing facilities of the highest competence.

          a. To learn more about the OSA and how they are helping keep our industry safe, please visit: https://www.osa-                                                                                                                                                                                           

      7. Ernö Abrasives is our in-house brand of products here at Rapid Abrasives.
          a. Ernö’s motto is built on strength, known for reliability.

To browse our Ernö line of products please visit the Rapid Abrasives Shop

We hope these tips help if you have more questions about grinding wheels, feel free to check out our FAQ.

And if you’re looking for sandpaper, stop by our Shop for our standard sizes, or check out our online calculator for custom sanding belts.