Attention all grinding shops: When was the last time you evaluated the performance of your grinding discs?

You may have had years of acceptable results using the same types of wheels. But did you know that new technologies produce wheels that last longer and deliver better results? Maybe it is time to put your old reliables to a performance test against newer products.

In this article, Weiler Abrasives, an industry-leading manufacturer of surface conditioning solutions and BlackHawk supplier partner, offers these tips for measuring the performance of different grinding products. You can view a complete Weiler test demonstration in this video.

Think Performance, Not Price
Price is often the driving factor behind wheel selection. But price is just one factor in your total operating cost. A cheap wheel might prove more expensive over time due to replacement costs. Similarly, a premium wheel may not deliver measurably better results than a less expensive but equally effective product. Depending on your criteria, wheel life may not be as important as speed or removal rate. Operator efficiency, ergonomics, and especially performance are important considerations. An empirical test gives you the means to measure that performance.

Test Objectives
When setting up a grinding wheel test, these are the primary factors to measure:

• Wheel life
• Wear patterns
• Removal rates
• G-Ratio

Weiler recommends testing multiple wheels over their expected lifespan. If a 4-inch diameter grinding disc has an average useful life of 30 minutes, Weiler advises six test-and-measure increments of five minutes each. In the video, Weiler experts show how to prepare, test and measure the results. They also present a simple spreadsheet for recording and graphing the data.

Note the G-ratio, which is the Amount of Material Removed divided by the Amount of Disc Loss. While not a “magic” number, G-ratio is a useful measure of a disc’s life cycle state. The higher the G-ratio, the newer the disc. Therefore, you want to test over the entire predicted life of a disc.

As the tests progress, the sample discs go through four life cycle stages:

• New — Most aggressive cutting, no visible disc wear
• Second — Wheel is “broken in” and delivers consistent results with even wear.
• Third — Results remain consistent, but the G-ratio starts to fluctuate
• Final — G-ratio falls considerably, and disc is harder to control, indicating end of life.

Feel vs. Fact: Off Hand or Automated Testing?
Machinists often ask which is better — manual testing by an individual, or a machine test with specialized equipment. The “correct” answer is both.

Each method has advantages. Off-hand testing allows testers to get a feel for the disc in their own hands with their own equipment and simulate “real” situations. Results, though, will vary by the individual tester, and the human factor introduces a consistency variable.

Automated testing requires special machinery, which is an added up-front cost. The benefits are consistent, reproducible results because pressures, angles and speeds can be precisely controlled. You lose the ability to feel the tool work in your hands.

For this reason, Weiler believes the most accurate testing program incorporates both methods.

General Tips

• Always wear appropriate PPE — safety glasses, shield, gloves, coveralls and earmuffs — before performing any grinding process.
• Unplug tools before changing or cleaning discs.
• Use an appropriate industrial-grade power cord or air supply.
• Remember: Pushing harder will NOT cut faster.
• Attack angles impact results! Aggressive angles allow more pressure for more surface removal while flatter angles allow more disc control.
• Use even, consistent strokes and let the wheel do the work.
• Perform off-hand tests at times during the day when your tester would normally be doing actual grinding work; this makes the test environment as close to reality as possible.

Summary
Testing helps you to find the right grinding wheel for your specific application, allowing you to improve performance and profitability while saving time and money. Give it a try. Do not be surprised if newer technology discs deliver better results.

Got a question about grinding products or techniques? Practical “at the spindle” knowledge is the BlackHawk difference. Our tool specialists are ready to help. Our team is backed by the expertise of industry leaders like Weiler Abrasives. When you need us, give us a call at 855-510-1001 (toll free).

Shop the complete line of Weiler products available online from BlackHawk here, or view our catalogs.