Internal Gear — Compact Power Transfer Solutions for Precision Systems
When space efficiency, accuracy, and torque density matter, YF Gear’s Internal Gears deliver unmatched performance.
As the heart of planetary reducers, robotic arms, and aerospace mechanisms, our internal ring gears combine space-saving geometry, low-noise meshing, and micron-level precision for the world’s most demanding drive systems.
Designed and produced using 5-axis CNC shaping, gear crowning, and carburized alloy steels, our gears achieve DIN 6–8 precision and 99.2% transmission efficiency, ensuring consistent operation under high-load or high-speed conditions.
| Specification | Range / Option | Technical Advantage |
|---|---|---|
| Module | 0.5 – 10 M | Suitable for precision micro to medium drives |
| Inner / Outer Diameter | Custom | Large gear ratio flexibility |
| Wall Thickness | As thin as 3 mm (titanium option) | Ideal for lightweight designs |
| Accuracy Grade | DIN 6 – 8 / AGMA 11 – 13 | High repeatability under load |
| Material Options | 42CrMo, 20CrMnTiH, Titanium, POM | For strength, corrosion resistance & weight savings |
| Heat Treatment | Carburizing / Nitriding / Tempering | Extends fatigue & impact life |
| Surface Finish | Grinding, Anodizing, Polishing | Enhances smoothness & anti-corrosion |
| Noise Level | ≤ 60 dB | Excellent for robotics & medical equipment |
| Backlash | ≤ 0.1° | Ensures high-precision motion control |
Compact & Efficient:
Internal ring gear systems reduce outer housing diameter by 25% on average — perfect for miniature and high-density assemblies.
Superior Torque Density:
Our optimized tooth curvature and contact ratio increase torque transfer by 40% compared to standard external gears.
Long-Life Durability:
42CrMo gears with plasma nitriding show > 3× surface fatigue resistance over untreated steel.
Noise & Vibration Reduction:
Tooth crowning and precision grinding eliminate edge contact, reducing vibration under alternating loads.
Custom Design Support:
Upload your CAD or sample — our engineers will analyze gear geometry, meshing, and load path for optimal results.
| Aspect | Internal Gear (Ring Gear) | External Gear (Spur/Helical) |
|---|---|---|
| Tooth Position | Teeth on inner circumference | Teeth on outer circumference |
| Direction of Rotation | Same direction of meshing gear | Opposite direction |
| Design Compactness | Space-saving layout | Requires more radial space |
| Torque Capability | High due to multiple contact teeth | Moderate |
| Noise & Smoothness | Quiet with proper crowning | Medium depending on cut |
| Backlash Control | Easier to tune for small angles | Moderate |
| Typical Applications | Planetary reducers, robot arms, instrument rotors | Automotive transmissions, pumps, gearboxes |
Quick Tip:
Choose Internal Gears when you need space-efficient high-torque transmission in closed systems or rotary modules.
1️⃣ Design & 3D Simulation – Meshing analysis using KISSsoft and FEA
2️⃣ Gear Shaping / Hobbing – 5-axis machining for micron tolerance
3️⃣ Heat Treatment & Nitriding – Uniform hardness and tooth core strength
4️⃣ Precision Grinding & Polishing – Improves surface finish (Ra < 0.8 µm)
5️⃣ Inspection & Testing – CMM, profile analysis, noise tests
6️⃣ Assembly Verification – Pair fit & backlash confirmation
7️⃣ Final Cleaning & Packaging – Anti-corrosion protection for shipment
Robotics & Automation: Internal gears in actuator drives and joint reductions
Planetary Reducers: Compact multi-stage transmission systems
Medical Devices: Precision imaging equipment & rotation mechanisms
Aerospace: Lightweight internal ring gears for satellite orientation
Industrial Machinery: Servo motors and automation lines
Renewable Energy: Wind turbine control gear modules
Each gear undergoes durability testing under load cycles > 1 million revolutions, ensuring uninterrupted performance in critical systems.
| Performance Need | Recommended Gear Type | Preferred Material |
|---|---|---|
| Compact & lightweight | Internal Gear (Titanium) | Ti Alloy / POM |
| High torque & rigidity | Internal Gear (Steel) | 42CrMo / 20CrMnTiH |
| Low noise & smoothness | Crowning Internal Gear | 42CrMo / Stainless |
| Corrosion resistance | Coated Internal Gear | SS316L / Plated Steel |
| Prototype development | 3D Printed Internal Gear | Resin / Nylon |
“Performance, Precision, Partnership”
1. Dimensional Consistency – Can the gear maintain true roundness after heat treatment?
✅ Yes, we use CMM and metrology scanning to control deformation ≤ 0.02 mm.
2. Assembly Fit – Will it match existing planetary stages?
✅ We offer full reverse engineering based on samples or CAD data.
3. Lubrication Compatibility – Suitable for synthetic or dry film lubricants?
✅ Both; our coatings are tested for PTFE and graphite lubrication systems.
4. Surface Noise & Wear Testing
✅ Each batch undergoes vibration spectral analysis to detect micropitting before shipment.
5. Replacement Support – Can you supply matching internal + planet gear sets?
✅ Yes, complete matched gear sets with pre-measured backlash and tooth pattern reports.
Q1: What is an internal gear?
A gear with teeth cut on the inside surface of a cylinder or cone, meshing with an external pinion to transfer motion within a compact housing.
Q2: What are the benefits of internal gears over external gears?
They reduce installation space, enable same-direction rotation, and offer high load distribution efficiency.
Q3: What precision can YF Gear achieve?
Our gears meet DIN 6–8 or AGMA 11–13 standards with ≤ 15 µm pitch deviation.
Q4: Can you produce thin-wall titanium internal gears?
Yes — we’ve produced ≤ 3 mm wall thickness for lightweight robot joints and medical scanners.
Q5: What’s the lead time for custom orders?
Standard samples 3–5 days, bulk production 7–15 working days depending on geometry.
Q6: Are your gears RoHS / ISO certified?
Yes, all products comply with ISO 9001 and RoHS requirements.
ISO 9001 Quality Management System
RoHS Compliance (lead-free manufacturing)
DIN 6 / AGMA 13 Precision Certification
100% CMM and tooth contact inspection
Gear Noise Test & Durability Validation
Need a custom internal ring gear for your robot or reducer project?
Upload your drawing or 3D model — our engineering team will provide a free consultation and quotation within 24 hours.
[ Request a Quote Now →]
Fast response | Engineering review | ISO certified production
