Pay attention to abrasives: Turning Performance

A few years ago, one of our local industrial sales representatives was giving his best pitch. He told me we should use his brand of coated abrasives, and I joked that he was trying to sell sandpaper to me.

“We sell a million dollars’ worth of sandpaper in a year,” he replied, “so we refer to them as coated abrasives.”

This lighthearted conversation made me think about the significance of abrasives in metalworking and how the application of abrasive products often is not given the same considerations as other metalworking processes.

Metalworking professionals use abrasives to clean parts, shape geometries, prepare surfaces, improve appearances, size features and cut parts. Today’s metalworking would not be possible without modern abrasives.

The grinding attachment for the 200 metric ton (220 ton) lathe at Mitsubishi Hitachi Power Systems Americas uses a large aluminum oxide wheel. Image courtesy of C. Tate

Abrasive grains like pumice, calcite, walnut shells and garnet, which is the most common grain in sandpaper, occur naturally and have been used by humankind for thousands of years. Technological advances have resulted in human-made materials, such as silicon carbide, synthetic diamond and aluminum oxide, which is the most frequent of these in modern metalworking. Human-made abrasive grains are the most prevalent material in contemporary manufacturing.

Types of Abrasives

Abrasive products are manufactured in various forms and presented to a workpiece in numerous ways to achieve the desired results.

Bonded abrasives are made by combining abrasive material with a bonding agent. The mixture then can be formed into many different shapes, creating grinding wheels, cutoff wheels, grinding points, dressing sticks and many other formed abrasive products.

Welding superalloys requires a lot of cleaning with abrasives to ensure weld quality. Image courtesy of C. Tate

Coated abrasives are probably the most typical abrasive product as this is the group of goods we generically refer to as sandpaper. As my salesman friend pointed out, this family of abrasive materials is far more significant than we sometimes realize. Coated abrasives are constructed by applying a binding agent like glue or resin to a backing material, such as paper, cloth or something similar. The abrasive grains are applied to the binding agent and coated again to create a flexible product that has a single layer of abrasive material.