If you need to machine small polygon or similar shaped holes smaller than one-quarter of an inch, micro rotary broaching may be for you. Rotary broaching tools can be used with Swiss machine tools and other rotating spindle equipment designed for making small parts. The rotary broaching tool holder is capable of holding 8mm shank broaches, which come in standard hexagon forms as small as .051". Custom made hexagon broaches smaller than .051" are also available. T10 six lobe broaches with the 8mm shank are stock items. Even though they are very small, many of the broaches in this size range are available with standard pressure relief holes.
In addition to standard hex, square and six lobe forms, custom rotary broaching tools can also be manufactured by Polygon Solutions. These would include double hex, double square, spline and serration forms. Rotary broaching does have some depth limitations, typically limited to about one to two times the diameter. Polygon Solution's rotary broaches are designed to reach two times the depth if possible. The rotary broaches also have some manufacturing limitations. The inside radius on a form cannot be smaller than .003" - .005", and the major diameter of an 8mm shank broach should not exceed .50".
Various materials can be machined when micro broaching. Soft steels, brass and aluminum are ideal. However, stronger materials like stainless steel and titanium can also be broached. The resulting finish can sometimes be adjusted by optimizing the speed and feed of the tooling. Tool life can also be optimized through various options available from Polygon Solutions, such as coatings, premium broach materials, and custom flat to flat dimensions.
The best way to get started is to send a print or drawing to Polygon Solutions along with any questions you may have. We will get back with you with our tooling suggestions, and do our best to answer your questions.