Insert Broaching on a CNC Lathe


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In our debut issue of this e-newsletter in July 2008, I wrote about rotary broaching, which is only one type of broaching. Now I’m here to explain broaching without rotary, or simply put, “insert broaching.”

Insert broaching technology is designed to produce keyways, grooves and slots on a CNC lathe. The tool is mounted on the machine’s tool turret with the other turning and rotary tools. It is fed into the workpiece with a reciprocating motion and is continuously adjusted by the machine’s CNC in the X and Y axes, as required, to produce the necessary slot width and depth. A C axis is required to index a part with several grooves spaced at regular intervals around the bore circumference.

The insert-type broaching tools have a round shank with broad, flat clamping surfaces that are 90 degrees apart to permit mounting the tool on any type of CNC lathe. Tools with brazed or replaceable carbide inserts are commonly used for broaching operations, because doing so makes it unnecessary to re-zero the tool after a new insert is installed. The tool body remains installed in the lathe’s turret during insert replacement. To read more about this technology, visit “Broaching on a Lathe.”

A twist on the replaceable insert concept, developed by Razorform Tools, is a tool system designed with two cutting edges per TiN-coated, micro grain carbide insert. Once one insert edge becomes worn, a machine operator removes two screws securing the sizeable insert to the tool body and flips the insert around to the second cutting edge. The company says this technology not only decreases tooling cost, but also increases tool life and performance. Read “Indexable-Insert Broaching Tool Technology for Lathes” to learn more about this concept.

For a more specific application such as medical, read, “Forming Hex Holes for Bone Screws,” which explains the indexing-broach process using four-point or two-point punch broaches.



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