12mm Planetary Roller Screw

Prepared by Micro Roller Screw. Created 2026-10-31 (repository record). Evidence reviewed 2026-10-31. Catalog editions are identified below; current availability and application approval remain to be confirmed.

A standard planetary assembly uses a central threaded shaft, orbiting threaded rollers and a surrounding nut. This page focuses on the traveling-nut planetary layout. The broader 12mm miniature guide covers general packaging selection; an inverted architecture needs its own nut and rotor envelope review.

Rollvis handbook, printed pp. 2–4 provides the architecture context. These schematics do not establish nut dimensions, shock endurance or a buildable actuator diameter.

These are third-party benchmarks, not a MicroRollerScrew stock specification. Ca is a dynamic fatigue rating; C0a is a static rating, not a recommended continuous working load. Confirm the selected nut arrangement before applying either value.

Open the original ratings (printed p. 24) and root dimensions (printed p. 25). The 12×5 single-nut row lists maximum axial backlash of 0.05 mm; a universal 0.01–0.03 mm claim would be incorrect. Actual supplied play must be specified.

Rollvis handbook, printed pp. 11–15 explains nominal life, compliance, speed and drive torque. The Euler/root-section calculation and 2.5 buckling factor here are explicit preliminary model choices, not the catalog’s own permissible-buckling formula.

Default inputs produce 120 mm/s, 2.504 N·m, 471.9 W and 1,099 running hours. The duty-adjusted estimate is 1,831 elapsed hours at 60% moving duty. It does not model idle-time damage or calendar service life.

Request a drawing review using these inputs. If a peak is repeated during motion, its effect must enter a revolution-weighted equivalent load spectrum. Entering only a lower “running” force can overestimate fatigue life. Split-nut life is withheld until both nut halves’ internal loads are known.

The structural model uses ideal Euler end conditions; whirling factors follow handbook printed p. 13. Real bearings, reduced journals and load paths can lower these estimates. The nut is not counted as a radial shaft support. At high compression, obtain a coupled dynamic calculation even if the zero-load RPM check is clear.

Stroke is nut travel; span is the free shaft length used by the structural screen. Span must exceed stroke, but that alone does not prove packaging clearance: allow for nut length, bearings, journals and overtravel. Fixed–free arrangements need the actual free length from the fixed support.

The series-compliance relation is 1/Kaxis = 1/Kshaft + 1/Knut + 1/Kbearings + 1/Khousing. It requires actual component stiffness at operating load and preload. This tool assumes loaded shaft length equals span and reports only EA/L; the actual length varies with nut position and support arrangement. It makes no assembly stiffness or positioning guarantee.

Handbook printed p. 12 distinguishes component compliance. Catalog rigidity factors are not constant N/µm values and cannot be substituted as a fixed nut spring.

Thermal illustration: assuming α = 11.7×10⁻⁶ /K, a 200 mm freely expanding shaft grows 70.2 µm for an assumed 30°C rise. The calculator does not predict temperature or restrained thermal force. If both ends are constrained, review housing expansion, bearing loads and assembly tension together; do not apply an automatic pretension recipe.

For a cost-sensitive axis, compare a ball screw at the same duty and accepted backlash. For a rotor-integrated actuator, review an inverted layout. A shared nominal diameter is insufficient to claim a fixed load, acceleration or fatigue-life advantage.

These are calculated examples, not customer deployments or endurance tests. They use the same model as the live tool. Values do not qualify medical, robotic or aerospace hardware.

The ≤2.5 mm short-stroke advisory and compression above 20% of Euler load are conservative review triggers in this tool. They are not sourced universal failure thresholds. Do not infer a safe stroke, flushing distance, cycle interval or wear-life multiplier from them.

ISO 3408-3:2006 covers ball-screw acceptance conditions and tests. It does not automatically certify this roller-screw assembly. Agree any adopted test method and tolerance with the supplier; no ISO, DIN, flight or medical qualification is asserted on this page.

• Define useful travel, lead deviation, repeatability, axial play and load-dependent stiffness separately.
• Request a traceable inspection report, shaft-end and bearing interfaces, preload/drag record and material documentation.
• Specify the environment and duty test, required sample quantity and pass criteria before production release.

Verified 2026-10-31. Original document editions below are distinguished from the verification date. Formulas and examples are preliminary calculations; no measured performance dataset is claimed.

1. Rollvis RV product tables (2024 upload), printed pp. 24–25: selected single/split ratings, direct efficiencies and root diameters. The linked rows define the third-party benchmarks only.
2. Rollvis satellite roller screw handbook (2018 edition): printed pp. 2–4 architecture; pp. 11–15 nominal life, compliance, zero-load speed and torque. Local screening factors and assumed steel properties are identified in the method section.
3. ISO 3408-3:2006 official scope: ball-screw acceptance conditions and tests; linked to clarify scope, not to claim roller-screw certification.

Public evidence is insufficient here to establish assembly stiffness, acceleration limits, short-stroke endurance, coating benefits, specialty material availability, comparative price or shipment timing. These remain drawing- and application-specific review items.

Use the live tool’s email action to include the selected configuration and entered duty. Email opens your mail client; attach drawings there. If email is unavailable, use the contact page with the same inputs.