When this product fits
Choose this family when the application, envelope, and validation needs match: Humanoid Robot Joints, Aerospace Actuators, Defense Systems.
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Inverted Planetary Roller Screw
Compact RVI architecture with a long internally threaded nut, smooth output shaft, and high load density for space-constrained electric actuators.
Target Buyer:Robotics, aerospace, and compact EMA teams that need high thrust in a short linear package rather than a catalog ball screw.
Capability Highlights
- Long internally threaded nut for short axial actuator envelopes
- Smooth translating shaft or push-tube integration options
- Custom preload, lead, stroke, and end-machining for OEM programs
- Inspection planning for lead accuracy, runout, torque, and backlash
Typical Applications
- Humanoid Robot Joints
- Aerospace Actuators
- Defense Systems
Engineering Focus
- Long nut grinding, lead accuracy, and pitch error control
- Outer diameter, stroke, and motor rotor packaging constraints
- Lubrication retention, sealing, and thermal path inside compact joints
- Bearing span, datum scheme, and rotor/nut interface review
Buyer Decision Notes
What to validate first
Start with custom diameter window and inspection evidence before comparing quoted price or delivery time.
Best RFQ starting point
Send the first drawing revision, STEP file, or sample photos with target load, lead, stroke, preload, quantity, and delivery country.
Key Evaluation Matrix
| Metric | Typical Range | Why It Matters |
|---|---|---|
| Custom Diameter Window | Approx. 8-100 mm project-dependent | Defines whether the inverted layout can fit humanoid joints, compact EMA tubes, or heavier industrial axes. |
| Lead Options | 1-20 mm typical custom range | Balances thrust, speed, back-drivability, and motor torque demand. |
| Inspection Focus | Lead accuracy, backlash/preload, runout, torque | Gives buyers evidence that the long internal thread and matched roller set are stable before actuator assembly. |
| Best Fit | Short axial envelope, high thrust, integrated actuator | Keeps the buyer from choosing inverted architecture when a simpler standard planetary screw is enough. |
RFQ Checklist
- Target dynamic/static load and life expectation
- Available integration envelope: OD, nut length, shaft length, stroke
- Required lead, backlash/preload, stiffness, and linear speed
- Duty cycle, temperature range, sealing, and lubrication assumptions
- Drawing, STEP, or sample availability and prototype quantity
Risk Controls
- Long nut pitch error causing uneven roller load sharing: Use lead inspection, profile checks, and matched set validation before sample release.
- Misalignment during actuator integration: Review datum scheme, bearing support, shaft end features, and rotor interface during DFM.
- Thermal growth reducing preload margin: Check duty cycle, motor heat path, lubricant, and target backlash/preload before freezing the sample drawing.
Product Gallery
Buyer FAQ
Why choose inverted over standard planetary?
Inverted screws are useful when the long internally threaded nut, push tube, or motor rotor can be integrated into a shorter actuator envelope. Standard planetary screws may still be better for simpler open-axis machines.
What are the typical lead options available?
Most custom discussions start around 1-20 mm lead, then narrow the choice by thrust, motor torque, speed, back-drivability, and positioning requirements.
Do you provide custom end machining for the shaft?
Yes. We support build-to-print shaft ends, journals, threads, flats, splines, keyways, and bearing seats when they are included in the controlled drawing package.
How is lubrication handled in inverted roller screws?
The lubrication plan is project-specific. We review grease type, fill volume, relubrication access, sealing, operating temperature, and duty cycle before sample approval.
Related Resources
Send drawings to [email protected] or WhatsApp [email protected] for a manufacturing review.
Inquiry Email
Include target OD, lead, stroke, load, quantity, and delivery country.
WhatsApp Engineering
WhatsApp Engineering Support
Best for quick RFQ clarification and drawing-review coordination.