American Machinist

CBN at high speeds. (electroplated cubic-boron-nitride grinding wheels) (includes related article)

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ELECTROPLATED CBN wheels have been used to successfully grind profiles in hardened-steel components for a number of years. In production grinding at Tooling & Production Systems Inc (Sussex, Wisc), for example, wheels made of Borazon-brand cubic boron nitride from GE Superabrasives (Worthington, Ohio) on Guhring machines operating at nearly 150 m/sec (nearly 30,000 surface ft/min) routinely gobble hardened alloy steel at very high rates of material removal and slash cycle time. AM-June'89, p75).

Yet for all their efficiency, they are limited by one factor: The superabrasive grain is embedded in a metal matrix-and not held in a strong chemical bond as in a conventional grinding wheel-so wheel performance at high metal-removal rates can be improved upon. Recently, tests done by wheelmaker Norton Co (Worcester, Mass) on a new bond system show promising results for even higher metal-removal rates than electroplated-CBN wheels for the same poweroutput.

Limits of electroplating

Electroplated-CBN wheels are made by attaching a single layer of cubic boron nitride abrasive to a metal core, usually through the electrodeposition of nickel. As the nickel is deposited, it entraps the CBN particles in a strong mechanical grip. Due to the high concentration of CBN and the nickel matrix, these single-layer wheels cannot be shaped with the normally accepted systems used for resin-, metal-, and vitrified-bond wheels. …

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