Finishing Process Extends Life Of Cutting Tools And Components

New materials and coating technologies have greatly increased the life and general performance of cutting tools. A new surface finishing technology that originated in the optics industry offers an alternate means for improving the durability of tools made of carbide, cobalt, HSS and PCBN. The Mikronite process, developed by Mikronite Technologies Inc. (Eatontown, New Jersey), is a dry mechanical process that combines compressive forces and abrasive media to polish and strain-harden the entire surface of a tool or workpiece. What this lapping-like process creates is a hardened surface with increased lubricity, smoothness, and corrosion and wear resistance properties. What it doesn’t do is apply a coating or plating to the surface.

Mikronite lends itself to complex geometries found on tools such as hobs, drills, taps and reamers, in addition to cutting tool inserts. The heart of the system is a reverse-centrifugal accelerating agitator. Tools (or workpieces) are placed in a container that is filled with an abrasive, non-caustic medium. The container installs on the agitator. The agitator spins the container clockwise, while at the same time, it rotates the spinning container in a counterclockwise circular path.

This motion subjects the workpieces to forces in excess of 30 Gs, but it does not allow them to contact the container wall. It also causes the abrasive medium to slide uniformly across the workpiece’s surface at an evenly distributed pressure. For metals, this compresses and weaves together surface fractures to a controlled depth without changing workpiece size, shape or metallurgy. This cold plastic deformation can yield a surface finish of less than 1 micron Ra while providing an optimal combination of outer surface hardness and inner ductile properties. It also allows steels, for example, to better resist corrosion.

The process is also used for automotive applications to improve durability of interacting components by reducing the coefficient of friction between mating surfaces. Performance racing companies are currently treating power transmission, valve train and various other engine components. In addition, the process is being used to polish medical and dental parts, as well as aerospace components such as engine turbine blades and bearings. Mikronite is appropriate for finishing steel, aluminum, titanium, bearing steels, tool steels, tungsten carbide, silicon nitride, brass and bronze, as well as ceramics and plastics.