How does a rotary broach make a hexagonal hole?

Answer 1

You can find great videos on how the rotary broaching process works at Polygon Solutions website.

Rotary Broaching, also known as Wobble Broaching, is unlike the conventional broaching method. The conventional method has a sequence of polygon forms that increase in size and are pushed through a hole until the desired form size is achieved. Rotary Broaching can achieve this in one pass by cutting the full form, one corner at a time, without the need for a secondary operation. This works exceptionally well on Horizontal or Vertical Spindle Machines such as Lathes, Mills, etc.

Rotary Broaching is a precision method for producing internal polygon forms at an extremely fast rate. The entire operation can be completed within seconds and can produce forms to 0.0005" accuracy or better. This advanced engineering has caused Rotary Broaching to become increasingly popular; especially in the medical, automotive, aerospace and Plumbing industries.

There are only two necessary components that achieve the Rotary Broaching process: 1) A Rotary Broach Tool Holder 2) Rotary Broach. The principle that makes this process work is the 1° angle of the cutting tool to the centerline of the work piece. This causes the Rotary Broach to shear into the work piece, with a chisel or scalloping effect, as the broach is fed into the part to the depth required. The Rotary Broach Tool Holder has a live spindle that holds the broaching tool, allowing the spindle to spin freely within the Tool Holder. It is then driven by contact with the rotating work piece. Our Rotary Broach Tool Holders are adjustment-free so there is minimal setup required and include such features as sealed bearings which require no routine maintenance and a pressure relief hole that allows air and fluid to freely escape.

With Rotary Broaching it is possible to broach such forms as:

⊕ Hexagon

⊕ Square

⊕ Torx

⊕ Serration

⊕ Keyway

⊕ Double Square

⊕ Double D

⊕ Double Hex

⊕ Involute

⊕ Spline

⊕ Spur Gear

⊕ J500

⊕ Other Polygon Forms

The two most common forms are hexagons and squares. Standard broach tools are made from M-2 High Speed Steel, but may also be produced from harder material such as M-42, PM T-15 or PM M-4 HSS. Coatings such as Titanium Nitride, Titanium Carbo-Nitride or Titanium Aluminum-Nitride can be added to produce additional strength, longevity and durability.

These forms can be broached in aluminum, brass, steel, titanium,

plastic and other materials at a depth of up to 2 times the diameter

of the broach.

Rotary Broaching is the most superior method used to get a polygon

form into the end of a part without the need for a secondary operation.