How a Grinding Wheel Works
Grinding wheels for portable power tools belong the ‘resin bonded’ family of bonded abrasives. Below is a brief description of the raw materials used in their manufacture, and an explanation of how the wheel actually works.
Abrasive Grains
The four main types of abrasive grains used in Resin Bonded Wheels are:
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Aluminum Oxide
- Tough, blocky, wedge shaped grain.
- Performs well on carbon steel, stainless steel and aluminum.
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Silicon Carbide
- Extremely hard and sharp, but fractures more easily than aluminum oxide.
- Performs well on cast iron, nonferrous metals (aluminum) and non-metallic materials including concrete, brick, marble and glass.
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Zirconia Alumina
- Very tough, sharp and dense.
- Lends itself to higher temperatures and heavier pressures present in high-stock removal applications.
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Ceramic
- Sharp mircocrystalline grain – cuts aggressively under light to moderate pressure.
- Its quick cutting capability makes it suitable for grind-ing stainless steel, titanium, and high-nickel alloys.
Determining Grit Size
Abrasive grains are sized by passing them over screens having a certain number of openings per linear inch. The number of openings per linear inch in the screen through which the particles just pass determines the grit size. Resin bonded wheels typically use relatively coarse grits such as 24 and 36.
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Coarse Grit Size (30 Grit)
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Fine Grit Size (108 Grit)
Components
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Abrasive Grains
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Resin Bonds
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Fiberglass Reinforcing
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Arbor Ring
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Spin-On Hub
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Wheel Label
The Cutting Tool Principle
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Abrasive grain begins to cut chips from the workpiece’s surface. As it does, the grain begins to wear down. It fractures, presenting a new sharp edge.
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Other abrasive grains are revealed as the wheel bond wears from contact with the workpiece.
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Before the edges of the abrasive grain become too dull, they are torn away from the wheel bond, allowing other abrasive grains to come into play.
