Known for its wear resistance, stellite is a cobalt-chromium alloy that has recently become a popular substitution for carbide in woodworking tools. As stellite becomes more common, many manufacturers are finding that it is a particularly difficult material to grind. Attempts at grinding stellite with a general-purpose CBN wheel result in the material being pushed along the surface, rather than cut away. This causes large burrs to form during the grinding process and reveals an uneven surface finish.
Many wheel consumers will already have a CBN wheel in their arsenal, but as previously discussed, not every CBN wheel is designed to cut stellite. If you’re a return reader you may recall the many times we have discussed the importance of considering what material is to be cut when choosing the grit size, shape, and bond structure of your grinding wheel. General-purpose CBN wheels are designed to grind hardened carbon steels using a blockier-shaped grit. In contrast to carbon steel, stellite is a much more ductile material. Blockier CBN particles can easily shear off bits of hardened steel but fail to completely remove stellite from the grinding surface, pushing it along and creating large burrs.