Description
Carburized Sun Gear
Case-hardened sun gears for high-cycle planetary duties where tooth-surface wear resistance and a tougher core are both important.
Specify the sun gear as part of a planetary mesh
Carburizing is frequently paired with alloy gear steels in power-transmission work because it can create a hard wear-resistant case while retaining a tougher core. The required steel grade, effective case depth, tooth hardness, core condition and post-heat-treatment finishing must be specified together.
For quotation, the most reliable input is the released drawing plus mating-gear data. If the design is still open, provide the required ratio, torque, speed, duty cycle, package envelope and interface constraints so the unresolved items can be identified before manufacturing.
Information used to define the ordered part
Sun gears are not interchangeable simply because two parts have a similar diameter. The tooth system and the rotating interface must match the planetary stage.
| Component | Spur or helical, case-hardened |
|---|---|
| Primary interface | Bore/spline/shaft feature per drawing |
| Tooth system | Metric module or diametral pitch (DP) as defined by drawing |
| Pressure angle | Drawing-controlled; do not assume from outside diameter alone |
| Tooth count | Required for quotation and mesh verification |
| Gear quality | ISO, DIN, AGMA, JIS or customer-specific requirement can be reviewed as stated on the drawing |
| Materials | Alloy and carbon gear steels selected to drawing; examples used in industrial gear work include 20CrMo, 16MnCr5, 18CrNiMo7-6, 8620-type and 42CrMo families |
| Heat treatment | Carburizing, nitriding, induction hardening, through-hardening or Q&T where appropriate to the design |
| Inspection | Tooth geometry, runout, bore/spline/journals and drawing datums as applicable |
| Supply basis | New design, drawing-to-print, sample-supported replacement or matched planetary set |
Check sun, planet and ring data together
A conventional planetary stage combines a central sun gear, one or more planet gears, an internal ring gear and a carrier. The tooth counts and mesh geometry constrain each other. For a replacement, measuring only the damaged sun gear can miss profile shift, backlash strategy or mating-gear wear.
When available, send the planet gear and ring gear drawings, gearbox assembly drawing, original tooth counts, center-distance information and any contact-pattern or backlash requirement. This is especially important for helical planetary stages.
Process planning follows geometry, material and required quality
Manufacture typically separates soft machining from heat-treatment and hard-finishing operations. Distortion allowance, stock for grinding, spline condition and datum recovery after heat treatment all need to be planned before the first part is cut.
The manufacturing route can therefore differ even between two sun gears of the same module. Batch quantity also matters because it affects tooling, fixturing and which spline or internal-feature process is economical.
What to send for an accurate quotation
Send the drawing or a clear set of gear data, then add the operating information that is not visible on the drawing. A sample can support a replacement project, but it should not be used to guess an unknown heat treatment or quality grade.
| Geometry | Module/DP, tooth count, pressure angle, spur/helical form, helix angle and hand where applicable |
|---|---|
| Interface | Bore, keyway, spline, shaft, journal, thread and locating faces |
| Material / heat treatment | Material grade, hardness or case requirement, surface treatment if specified |
| Quality / inspection | Gear-quality standard and grade, runout, profile/lead or special inspection requirements |
| Duty | Torque, speed, duty cycle, reversals, lubrication and working temperature when relevant |
| Mating data | Planet/ring tooth counts or drawings, carrier/center-distance information |
| Commercial | Quantity, target delivery, packaging and Incoterm |
