Nut-driven inverted design for maximum stroke-to-length ratio.
Use an inverted roller screw when the actuator must place the nut inside or directly beside the motor rotor, maximize stroke-to-length ratio, and keep the output shaft compact. This is the most relevant architecture for humanoid joints, robotic fingers, and compact electromechanical cylinders where a conventional screw and traveling nut would be too long.
Share motor hollow-shaft dimensions, available rotor length, and bearing positions so the nut OD and screw OD are evaluated together.
Risk if missed: A screw sized only by thrust can become impossible to integrate once rotor wall thickness and support bearings are included.
Define the required usable stroke and hard-stop strategy before selecting lead and total screw length.
Risk if missed: Late stroke changes can force a new nut length and invalidate motor packaging.
Provide peak/continuous thrust, speed, cycle profile, and motor heat assumptions so clearances and lubrication are reviewed early.
Risk if missed: High-frequency oscillation can shift clearances and preload if the design treats the screw as a static catalog part.
| Metric | Typical Range | Why It Matters |
|---|---|---|
| Stroke Ratio | Up to 80% of total length | Enables highly compact linear actuators. |
| Model | Nut OD (mm) | Screw OD (mm) | Lead (mm) | Dyn. Load (Ca, kN) | Static Load (C0a, kN) | Typical App |
|---|---|---|---|---|---|---|
| ISR-0501 | 12.0 | 5.0 | 1.0 | 0.4 | 0.6 | Dexterous Hand |
| ISR-0803 | 18.0 | 8.0 | 3.0 | 5.5 | 8.5 | Wrist/Elbow Assist |
| ISR-1002 | 24.0 | 10.5 | 2.0 | 13.4 | 20.8 | Arm Main Drive |
| ISR-1204 | 28.0 | 12.0 | 4.0 | 20.5 | 32.6 | Leg Secondary Drive |
| ISR-1304 | 30.5 | 13.5 | 4.5 | 25.0 | 45.0 | Leg Main Drive |
| ISR-2005 | 45.0 | 20.5 | 5.0 | 65.0 | 120.0 | Torso / Heavy Knee |
| Capability | Evidence | Buyer Value |
|---|---|---|
| Long internal thread grinding | Internal thread inspection, lead error trace, and nut concentricity report for the selected inverted design. | Addresses the main manufacturing bottleneck that limits inverted roller screw availability. |
| Actuator-level interface review | DFM notes covering rotor fit, shaft extension, bearing support, anti-rotation, and assembly sequence. | Reduces the chance that a purchased screw passes bench inspection but fails actuator assembly. |
| High-duty-cycle preload control | Preload torque measurement, running torque trend, and matched clearance record by lot. | Gives robotics teams a measurable way to compare samples across suppliers. |
Step 1
Preliminary inverted architecture with nut OD, screw OD, lead, stroke, and rotor integration notes.
Acceptance: Buyer confirms the package fits motor, housing, and joint envelope constraints.
Step 2
Machined sample with lead accuracy, preload torque, axial play, material, and heat-treatment records.
Acceptance: Sample completes bench motion, thermal, and backlash checks under buyer duty cycle.
Step 3
Repeatable pilot-lot inspection package and actuator assembly feedback loop.
Acceptance: Assembly yield and performance variation are stable enough for supplier qualification.
Speeds up to 2000 RPM depending on diameter and lubrication.
Yes. Send rotor ID/OD, active motor length, bearing stack, stroke, thermal assumptions, and anti-rotation concept so we can review the inverted screw package as an actuator subsystem.
Inquiry Email
Please include screw type, diameter, lead, stroke, load, drawings, STEP files, and quantity timeline.
NDA signing supported prior to drawing uploads.
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