Safety

Blotters - A Lasting Impression

21 Jun 2023

Experienced grinding operators know the importance of blotters. Blotters are compressible washers that are placed between abrasive wheels and flanges to prevent the flanges from slipping and protect them from wear. They are also important for wheel safety and are required by the safety code ANSI B7.1.

However, even experienced operators may not realize that blotters are useful for checking the condition of grinding wheel flanges. (The importance of flange condition is discussed in other articles, such as “Flanges: A Critical Link in Grinding Wheel Safety.”)

Since blotters are compressible by design, when mounted they take on impressions from the surfaces of the wheel and flanges. These impressions provide insights into the flange condition and mounting procedures. So next time you perform a wheel change, check for the following:

Evidence of Movement

The blotter should display NO signs of slipping or other movement of the grinding wheel inside its flanges. Scratches, tears, or other wear marks (as in Figure 1) may indicate that there has been movement.

Scratches, tears, and other wear marks on a grinding wheel

Concentrated Pressure

The blotter impressions should be even and NOT indicate concentrated flange pressure. Figure 2 shows a segment blotter with a sharp indentation on the bottom side. This condition actually caused the segment to crack.

Segment blotter with a sharp indentation on the bottom side

Complete Contact

The blotter should show evidence of complete flange contact over the entire bearing surface. Figure 3 is an example of partial flange contact; notice the top section where no flange impressions are visible.

Regularly examining blotters after use is an easy and valuable way to check for potential mounting problems. Add it to your preventive safety plan alongside periodic flange inspections and good mounting procedures.

For additional information on this topic or if you need any other abrasive safety information, please review the Norton Product Safety page, ANSI, OSHA and all literature provided by the abrasive wheel and machine manufacturer. You may contact the Saint-Gobain Product Safety Department at (508) 795-2317, or contact your Saint-Gobain Abrasives representative with any safety related questions.