KEVOS® MAKEOS · Gears
Gear Hobbing Cycle Time
How long does it take to hob this gear at the chosen hob speed and feed?
Hobbing time for a spur or helical gear from the number of teeth, hob starts, hob diameter and cutting speed, axial feed per work revolution, face width, helix angle, full-depth approach and overrun, for one gear or a stack.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Number of teeth in the gear | Teeth in the gear being cut. | |
| Hob starts | Number of threads on the hob. | |
| Hob outside diameter | mm | Outside diameter of the hob. |
| Cutting speed | m/min | Hob cutting speed for the tool and material. |
| Axial feed per work revolution | mm/rev | Axial feed of the hob per revolution of the work. |
| Face width (of the stack) | mm | Total face width of the gears cut in one pass. |
| Whole depth of tooth | mm | Whole depth of the tooth (about 2.25 × module). |
| Helix angle (0 = spur) | ° | Helix angle of the gear. |
| Overrun | mm | Run-out beyond the face. |
| Gears in the stack | Number of gears cut together. | |
| Load and unload time per stack | min | Handling time per cycle. |
Method and formulas
- Hob speed n = 1000 V_c ÷ π D_h; work speed = n × starts ÷ z.
- Approach for full depth ≈ √[h (D_h − h)].
- Travel = b ÷ cos β + approach + overrun; time = travel ÷ (feed × work speed).
- Example: 40 teeth with a 1-start 80 mm hob take 5.9709 min to cut.
Limitations
- Single climb or conventional pass; roughing and finishing passes add time.
- Feeds and speeds come from your tooling supplier and machine.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Quote gear cutting time
- Compare single- and multi-start hobs
- Balance hobbing with other operations
Who it is for
- Gear manufacturing engineers
- Estimators
- Machinists
What you get
- Hob and work speeds
- Cutting time per gear
- Floor-to-floor time per gear
Interpreting the result
- A two-start hob halves cutting time but coarsens the feed marks; check the finish needed.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3347–3349. Topic reference; no source tables or recommended settings are reproduced.
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