These stainless steel surgical implants were broached on a machine which allowed for the varying lengths. In the two-pass operation, serrations and one end radius were broached on the first pass. Then the part was rotated 180°, and the remaining serrations and radii broached to finish the part.
Teeth and Serrations
As shown by these three examples, teeth and serrations of any size are easily created using broaching. The large gear teeth formed on the round rack of a tractor power steering unit were cut in one pass. The intricate serrations on the face and edge of the large tank motor mount were cut first by broaching the face serrations, then tipping the part 30° to do the edge. Approximately 3/4 of the circumference area of the two small telephone dialing mechanism parts was surface-broached in one pass.
Special slots, such as these "T" shapes, can be created in one or two passes. For a two-pass cut, the first pass generates the slot and the second pass forms the top of the "T". Most any metal can be broached this way. Brass, steel and copper parts are shown here.
The teeth on these pocket knife saw blades were cut in one pass using "on the fly" broaching. Starting with a solid edge, a cut was made at a 45° angle. Then, during a gap in the tooling, the fixture was indexed 86° in order to make the final cut and give the teeth their triangular form.
Hexes and Squares
A gap between the tools can allow parts needing forms like these to be indexed for complete broaching in one pass. This is referred to as broaching "on the fly". Multiple surfaces can be cut in one cycle.
A variety of slots, angles, keyways and radii can be successfully broached on most any material. M-2 tool steel, 4340 steel and 1018 low carbon steel are some of the materials represented. The secondary and final operations of these parts were completed by broaching. They were formed in just one or two passes.
The slots in these transmission shafts were broached in multiple in-feed passes on a patented shuttle in-feed table. Each 1/4" wide x 1/4" deep x 8-1/8" long slot received two successive roughing passes, followed by a final pass to eliminate tool marks and maintain close tolerances and surface finish specifications.
These cast ductile-iron motor mounts were both one-pass broaching operations. Working off of the cast surfaces, one part was surface-broached and the other broached internally. The pieces were completed maintaining SPC quality standards.
Referred to as "traditional" broaching, internal broach tools create keyways, involute splines, grooves, squares, and a vast array of generated forms. It is the most cost-effective way to mass-produce irregular or custom internal forms. A variety of metals are represented, including brass, copper, alloy steel, stainless steel and aluminum.
Hand tools are commonly broached items. Wrenches, medical hemostats and pliers are a few examples. Surface broaching was used on the jaws of the pliers, as well as on the open end of the wrench. Internal broaching was used for the box end of the wrench. The joint area of the hemostat was straddle-broached.