Gear tooth honing for precision

Gear honing is a finishing process that can be applied to external and internal spur or helical gears. Honing can improve the sound quality of shaved, hardened gears by removing nicks and burrs. Also, the process can improve involute, lead, tooth spacing, pitch diameter, run out and surface finish. Typically, shaved gears have a tooth surface finish ranging from 0.6 to 1 micron while honed gears are in the 0.2 to 0.35 micron range. Honing always improves the characteristics of shaved, hardened gears.

Honing can also be used to prolong the wear life and increase the load carrying capacity of hardened ground gears by improving surface finish to a point where upto 80% surface contact can be achieved.

General-purpose honing tools are made in variety of resin and abrasive mixes for gears that have been shaved and heat-treated. They are available in eight grit sizes ranging from 50 to 600 grit. In order to obtain extra critical surface finishes around 0.15 micron and maximize the total tooth contact area on ground or shaved gear teeth that have been honed, use a poli tool. This tool is flexible, porous polyurethane polishing tool that uses an abrasive liquid compound (about 500 grit) during the finishing process.

Honing tools are made in diameters from 85 to 320mm with 25,40,50mm face widths. Most gear hones are made with approximately 225mm diameter.

Honing tools are mounted on special machines in a crossed axes, controlled mesh relationship with the gear to be honed. During the honing cycle, the work gear is run with the honing tool at about 180 rpm. The honing tool is traversed back and forth across the gear face and the direction of rotation of the honing tool is reversed at the end of each stroke. Particles removed by the honing process are flushed away with conventional honing oil.