Honing provides benefits for all types of tools

Honing the edge of a cutting tool has benefits, including improved tool life, improved workpiece surface finish, reduced spindle load and reduced overall manufacturing cost.

Mutschler Edge Technologies LLC, which builds edge-prep machines, defines honing as the creation of a controlled radius and surface finish improvement at the intersection of two surfaces that form the cutting edge. Honed edges can be full radii, waterfall or reverse waterfall.

A machine preps the cutting edges of carbide inserts. Image courtesy of Mutschler Edge Technologies

Honing provides benefits for all types of tools, including HSS and carbide ones. The major benefits occur on a carbide tool prior to coating it. The radius edge allows the coating to better adhere to the tool surface because no dead-sharp corners or burrs are present. A coating reduces friction, increases the contact area of the cutting edge to the workpiece and strengthens the tool. If not honed prior to coating, the edge can fracture and expose the substrate, shortening the life and effectiveness of the coating and the tool. The surface finish of the edge is also improved, reducing friction and allowing for improved chip evacuation.

Tools that are not coated can also benefit from the controlled radius applied to the cutting edge.

Honing is a dry process achieved by applying a nylon-abrasive-filament brush to the edges of the cutting tool. The brush filaments are constructed from a nylon carrier that is co-extruded with an abrasive grain. This means that as the brush wears, new abrasive grains are constantly being exposed to the workpiece. These flexible brush filaments act as “flexible files,” wrapping and wiping across all edges evenly.

There are two separate dynamics to using these brushes: the cut that the abrasive creates and the force of the filaments as they contact the surface. Many factors determine the result, such as speed, direction, cycle time, depth of engagement and centerline placement.