Selecting the Right Tool for Flex-Honing

From firearms to valve guides, flexible honing can be used to remove loose, torn, and folded metal from the internal surfaces of bores and cylinders. Selecting the right honing tool for your deburring, edge blending, cylinder honing, or chamfer radiusing project is a straightforward process - if you can answer a few questions. Is the internal diameter (ID) of the workpiece smooth or threaded? Then there’s a basic application requirement to consider. Do you need a flexible hone for surface finish improvement, deglazing, scale removal or cross-hole deburring?

By answering a few easy questions the best Flex-Hone can be selected for your use. The Flex-Hone comes in different types of abrasives, different grits and a huge range of sizes, a BRM exclusive feature not available with other brands of flexible hones or flexible honing tools. Abrasive globules are laminated onto the ends of flexible nylon filaments, where they form so-called “balls” or “dingle berries”. A big choice of abrasives are available to finish a variety of materials. Aluminum oxide is great for abrading softer metals like aluminum, brass and bronze. Silicon carbide is the workhorse and finishes cast iron, mild steel and most stainless steels. Boron carbide and diamond are better for heat-treated steels, carbide and ceramic. The base material determines the abrasive to choose and these are only a few of the abrasives available. Abrasive type isn’t the only consideration. Choosing the right honing tool also involves selecting the right grit size – the size of the particles in the abrasive itself. Typically, grit sizes are based on ANSI, FEPA, JIS, or proprietary grading system standards and have a numeric value.

For Flex-Hone® users, grit selection just means determining the amount of work to perform and the degree of surface finish improvement that’s required. Depending on the starting finish, each grit size produces a surface finish that corresponds to a roughness average (Ra), a measurement that represents the average of all the peaks and valleys in a sample section. Ra is measured in micrometers or microinches. As a rule, a higher grit number is finer, produces a lower RA and provides a smoother finish. A lower grit number is coarser and produces higher RA values. These are general ranges, but provide a solid starting point for proper grit selection.