Perhaps the best way to describe Extrude Honing is to start with a view to conventional honing, where a cylindrical part, or workpiece has small amounts of material removed to achieve a desired size and/or surface finish.  Examples of this would be the cylinders in an engine or the wheel cylinders in a car’s brake system.
This is done by passing rotating stones or cutters to remove material.  While this works really well as far as it goes, it is limited in application to a cylindrical work piece. 
But what if other shapes could be addressed, like squares, rectangles, spider shapes, or go around corners to remove material?  Extrude Hone does this.
In the Extrude Hone process, two vertically opposed cylinders extrude abrasive media back and forth through the passages formed by the workpiece and the tooling.  Abrasive action occurs wherever the media enters and passes through the most restrictive passages.
The basic elements in the process include:

  • the Tooling, which confines and directs the media flow to the desired areas of the workpiece
  • the Machine, which holds and dispenses the media, and controls the media extrusion pressure, along with flow volume
  • the Media, which determines the pattern and aggressiveness of the abrasive action that takes place in the workpiece.

By selectively permitting and blocking flow into, out of, and through the passages in the workpiece, the tooling can be designed to provide media flow paths through the workpiece that restrict flow at the areas where deburring, radiusing, and polishing are desired.  Frequently, multiple passages and/or parts can be processed simultaneously.
The consistent media slug length through all the cross holes in the cylinder pictured to the right demonstrates the uniformity of the Extrude Hone process.  Normally, tooling also contains the flow of the abrasive media to direct it between the extrusion cylinders of the machine.
A typical Extrude Hone machine has two vertically opposed media cylinders that extrude the media back and forth through the passages formed by the workpiece and the tooling.  The cylinders separate, for insertion or removal of the workpiece/fixture and clamp together to seal during processing.