Broaching and it's construction.

Broaching

Broaching is a multiple - tooth cutting operation with the tool reciprocating similar to the sawing operation described earlier.  The similarities end there, since in broaching, the machining operation is completed in a single stroke as the teeth on the cutting tool, called broach, are at increasing increasing height relative  to the feed per tooth of a milling cutter.  The material removal using the broach teeth is shown schematically  in Figure. Here, the dotted line indicates the amount of material being removed by the successive individual teeth.  Using broaching, tolerances of the order -0.013 to +0.013 mm can be easily obtained.  Very high surface finish is not the aim of broaching, and as a result it is possible to get 0.  80 um with normal broaching.  A better finish can be obtained by sacrificing tool life and employing expensive fixtures.

Sawing machine

Broach teeth

      Since each successive tooth removes only a small time, the tool life of a broach is very high.  It is possible to produce 2000 to 10,000 accurate parts with a broach between sharpening depending on the workpiece and tool materials used. 

    Some typical examples of internal shapes that can be very conveniently machined by using the broaching process are shown in Figure.

 Broach Construction

    In the above figure, the material being removed is shown in an exaggerated fashion for clarity, however, in!  actual broach, there are a large number of teeth, each of which will remove a small amount of material such that by the time the broach completes the operation, the component is completely machined.  A typical broach is shown in Figure. Broaching was originally developed for machining internal keyways, but looking the advantages, it has been widely used in the mass production of automobile component manufacture, for various other surfaces as well.

Broach profile

Construction pull broach