Internal & Ring Gears
Internal gears shaped or ground in bores from 60–800 mm, for planetary and clutch drives.
Internal teeth cut into a ring, usually as the fixed or output member of a planetary set. Accurately locating those teeth to the bore and the bolt circle is the whole job.
5–8 weeks
2 pieces
ISO 9001:2015
Technical Specifications
| Parameter | Value | Unit |
|---|---|---|
| Bore range | Ø60–Ø800 | mm |
| Tooth quality | AGMA 8–11 | class |
| Concentricity | 0.02 | mm |
| Module range | 1–8 | module |
| Face width | To 200 | mm |
| Bolt circle | ±0.05 | mm |
Available Materials
Typical Applications
- Planetary gearboxes
- Slewing rings
- Clutch drums
- Winch and crane drives
- Machine tool indexing
Surface Finishes
- Shaped teeth
- Ground teeth
- Nitrided
- Black oxide
- Phosphate coated
Industries Served
- Industrial Equipment
- Energy & Oil & Gas
- Mining & Construction
- Marine
- Rail
What drives the price of this part
Derived from the callouts on this page. Where a driver is not on the drawing, it is not on this list.
- Tolerance
- Concentricity at 0.02 mm is the tightest callout this family carries. Tightening a callout is a process decision, not a machining decision: below the standard ±0.005 mm the work moves to grinding or jig boring, and the price moves with it.
- Part size
- Bore range at Ø60–Ø800 mm decides which machine the part lands on and how many setups it needs. Size is the driver buyers most often leave out of a first enquiry, and it is the one that changes the quote fastest.
- Material
- The first material listed, Carbon Steel 4140 (42CrMo4), rates 6/10 on our machinability scale at 197–235 HB annealed · 28–32 HRC quenched and tempered. On this shop's scale a harder alloy means slower passes and more tool changes, and that is cycle time the quote has to carry.
- Order size
- Minimum order is 2 pieces, so on a first order setup and programming are spread over very few parts and they are most of the price. Repeat orders at the same quantity are cheaper without anything on the drawing changing.
See how cycle time is calculated in the machining time calculator and what else moves a price in the cost driver reference.
How these parts are inspected
Matched to the callouts above and the instruments actually on the floor.
- Coordinate measuring machine (Zeiss CONTURA G2, two machines, GR&R 8.4% on the critical feature)
- Dimensional report against the drawing, with a 100% check on critical features rather than a sample
- Certificate of conformance and the mill certificate with every shipment
- Bore gauges and an optical comparator for hole position and edge form
The full equipment list, with counts, is on the capability page; the inspection sequence is on quality and inspection.
Questions buyers ask
- Why is an internal gear harder to make than an external one?
- The tool has to reach inside the ring, so the shaping cutter and its holder must clear the bore. That limits the face width and the module compared with an external gear.
- Can you machine the teeth after hardening?
- Only by grinding, and internal grinding heads are limited in size. On case-hardened rings we normally grind the bore and bolt circle after heat treat and leave the teeth shaped.
Related part families
Precision Spur Gears
AGMA 8–12 spur gears, hobbed and profile ground, from 12 mm to 800 mm pitch diameter.
Helical Gears
Helical gears to AGMA 9–12 with ground flanks, for quieter drives and higher tooth loads.
Worm Gears & Wheels
Worm shafts and bronze wheels cut to matched centre distance, for high-ratio right-angle drives.