Broach Parts and Nomenclature
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Broach Parts and Nomenclature
Broach Parts and Nomenclature - The broach consists of the following portions:
The pull end occurs only on pull broaches and is to provide a means of quickly attaching the broach to the pulling mechanism. The front pilot guides the broach into the hot, and also serves as a rough no go gauge. The rear pilot is the size and shape of the finished hole, and guides the broach through the finished work.
| A. Pull end | B. Shank length |
| C. Root diameter. | D. Front pilot |
| E. Chip breakers | F. Tooth rise in this section |
| G. Roughing teeth | H. Cutting tooth |
| I. Semi finishing teeth | J. Total broach length |
| K. Finishing teeth | L. Rear pilot |
| M. Follower end | N. Notched tail |
| A. Gullet depth | E. Land |
| B. Pitch | F. Tooth gullet |
| C. Root radius | G. Hook of face angle |
| D. Cutting edge | H. Back off angle |
The follower diameter is, far a pull broach, often shaped such that it can be gripped by an automatic broaching machine and brought back to its starting position. Shank length must be sufficient to permit the broach to pass through the workpiece and be attached to the puller before the roughing teeth engage the work.
Mast of the metal removal is done by the roughing teeth.
Semi finishing teeth provide surface smoothness.
Finishing teeth produce exact size.
Chip breakers eliminate packing and facilitate chip removal.
The land is the tap portion of the tooth; it is ground to give slight clearance and thus farms the clearance angle or back off angle. Back off angle is a clearance or relief angle to prevent excessive rubbing on the work. This angle varies from 1/2 to 3 degrees.
Hook or face angle is equivalent to the rake angle of a single point tool and is a function of the material being cut it being 15-20° far steel and 6-8° for cast iron. Tooth gullet (or chip space) and pitch are especially important because the chips cannot escape from the cutter on inside cuts. Chips may curl up in the gullet (or chip space).
Naturally, the longer the cut and the greater the depth of cut, the larger is the volume of chips made. To hold this larger volume of chips, the teeth must be deeper and the pitch must be greater. The width of cut will not change the spacing needed.
The pitch is the linear distance from the cutting edge of one tooth to the corresponding edge on the next tooth. Pitch should be such that at least two (preferably three) teeth are cutting at any one time.
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