Internal Knurl from Rotary Broaching

Nov. 7, 2010 - PRLog -- The most common knurls are found on the outside diameter of a part. Knurls are raised grooves or serrations. However, there may be a need for straight internal knurling features; to provide a better grip on the surface, increase the  size of the diameter, or simply alter the appearance of the part. Whatever the case, one option for machining such an internal form inside a diameter is by rotary broaching.

   Rotary Broach tooling requires a tool holder and a rotary broach. The broach appears to look much like a punch. The broach is precision ground and held in the tool holder at a slight one degree angle. For most machinists, the angle is so slight that when measuring the finished product, the hole size appears to match the broach form exactly. First, a pre-drilled hole is put into the part, then the broach is indexed through the hole while the part is rotating. The broach rotates with the part, but the slight angle means it is only cutting one serration at a time. A drill or end mill can be used to clean out any chips that may remain.

   The knurling form is limited in size. Rotary knurl broaching should only be used in small forms with a .010 inch to .030 inch serration height per side, depending on the depth and material. The depth and diameter of the form is also limited to a maximum of about an inch. However, the knurl is not limited in shape. Nearly any shape desired can be accomplished by rotary broaching, including straight knurls, serrations, splines, involute splines, star shapes and irregular forms. The end result is also very precise, as most rotary broach tools are custom made to suit each application.

   Rotary broaching of internal knurl forms is a fast and easy way to accomplish serrations during production on your CNC machine or lathe. So the next time you consider adding serrated edges to the inside diameter of your part, get out the rotary broaching tool holder and ask for a quote on a custom rotary broach. You'll save time, money, and end up with a very precise knurl.

Polygon Solutions would be glad to quote your custom serration, spline or special rotary broach tool.

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Polygon Solutions specializes in rotary or wobble broaching tools for lathes and CNC machines. Our continuous effort is to develop cutting edge products and technical support for our customers. Our commitment to quality comes first in everything we do.
http://www.polygonsolutions.com
http://www.buybroaches.com