KEVOS® MAKEOS · Manufacturing
Broach Tooth Pitch
What tooth pitch should this broach have for its chip space and machine capacity?
Minimum broach tooth pitch from chip space, allowable pitch from machine capacity, the pitch to use, and the number of teeth cutting at once.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Length of cut | mm | Length of the surface being broached in the cutting direction. |
| Depth of cut per tooth | mm | Rise per tooth (one side for round broaches), from broach design data for the material. |
| Chip space factor F | Chip space factor: about 3–4 roughing and 6 finishing for brittle materials; 4–7 roughing and 8 finishing for ductile materials. | |
| Width of cut | mm | Width of the layer removed by each tooth. |
| Broaching pressure | MPa | Pressure per unit area of cut (depth × width) for the material and depth, from broaching data tables. |
| Usable machine capacity (70% of maximum) | t | Usable capacity of the machine in metric tonnes, taken as 70% of its maximum to allow for dulling. |
Method and formulas
- Minimum pitch = 3√(L d F).
- Allowable pitch = d L b P ÷ (9810 T).
- Use the larger of the two; teeth in contact = L ÷ pitch (at least two are needed).
- Example (the handbook case for cast iron): minimum pitch 28.142 mm, allowable 33.345 mm, so use 33.345 mm.
Limitations
- Design data for rise per tooth and pressure must match the material; this tool does not supply them.
- Pitch is usually varied slightly between teeth to reduce chatter.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Lay out a new surface or internal broach
- Check whether a broaching machine has enough capacity
- Find teeth in contact for a part length
Who it is for
- Tool designers
- Manufacturing engineers
What you get
- Minimum pitch for chip space
- Allowable pitch for machine capacity
- Pitch to use
- Teeth cutting at once
Interpreting the result
- If fewer than two teeth cut at once, reduce the pitch or broach two parts together.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 980–990. Topic reference; no source tables or recommended settings are reproduced.
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