Hybrid calculator + report
Run the load-life screen first, then use the report to judge package fit, evidence, and limits for 1.5 mm micro-actuators and precision mechanisms.
Preliminary capacity basis
C_a 0.8 kN / C_0a 1.2 kN
Self-serve load screen
<=100 N continuous
Lead assumption
0.5 mm for the calculator
Evidence review
Updated July 20, 2026
Decision summary
These conclusions keep the tool and report aligned: the calculator is a triage screen, while the report explains why a warning or resize result should not be overridden without engineering data.
The 1.5 mm standard planetary format is strongest when the shaft diameter must be minimized to fit in tight radial spaces, like micro-robotics or surgical tools.
Evidence: Architecture choice, manufacturing complexity, and internal Micro-RV packaging data.
Treat 100 N as the conservative continuous-duty screen. Loads above 100 N can be investigated, but need duty-cycle, lubrication, preload, and thermal review before quoting.
Evidence: Internal Micro-RV preliminary load table plus L10 screening assumptions.
Peak or theoretical capacity is not a published continuous catalog limit for this package. The calculator now blocks combinations above the conservative 1.5 mm review envelope.
Evidence: Public size-specific empirical data remains limited; use project validation.
In micro-scale applications (like biopsy tools) where stroke is <5 mm, rollers may not fully distribute grease. This can lead to stick-slip or accelerated localized wear.
Evidence: Tribology constraints at the 1.5 mm scale; requires specific grease selection and periodic run-in cycles.
A 1.5 mm screw cannot be responsible for side load, moment load, or actuator alignment. The application must include rails, bushings, or a guided carriage.
Evidence: Roller screw selection practice and micro-scale package constraints.
Method
The tool prioritizes an actionable first-pass decision: continue with CAD review, move into prototype validation, or resize before quoting. It should not be read as a final catalog rating.
| Step | Method | Limitation |
|---|---|---|
| Life screen | Uses a simplified L10-style estimate from preliminary C_a 0.8 kN, axial load, speed, 0.5 mm lead, and stroke. | Excludes shock load, side load, contamination, preload heat, lubricant breakdown, and inspection tolerance stack-up. |
| Continuous-duty screen | <=100 N, <=1,500 RPM, and <=50 mm stroke are treated as the self-serve review envelope for this 1.5 mm page. | 100-300 N, higher speed, or longer stroke needs a load spectrum, thermal review, and actuator guide assessment. |
| Output classification | The result is classified as success, warning, or resize/review so the user knows whether to request CAD, prototype review, or a larger package comparison. | A passing result is not a guaranteed catalog rating and does not replace drawing-level validation. |
Fig 1. Conceptual 1.5 mm micro planetary roller screw cross-section. Standard configuration allows for longer strokes but requires a longer overall assembly than inverted designs.
Specifications
Values below are screening inputs for this page. Final use requires project drawings, inspection plans, lubricant selection, and life-test criteria.
| Parameter | Screening Value | Boundary / Limitation | Source |
|---|---|---|---|
| Nominal screw diameter | 1.5 mm | Axial load only; radial and moment loads require external guides. | Internal Micro-RV preliminary specification. |
| Nut outer diameter | From 5.5 mm | Quote-specific wall thickness, preload, recirculation clearance, and housing interface must be confirmed from drawings. | Internal package concept, not a public guaranteed catalog value. |
| Lead used by calculator | 0.5 mm | Other leads change linear speed, efficiency, self-locking behavior, and calculated life. | Internal Micro-RV preliminary specification. |
| Preliminary dynamic capacity | C_a 0.8 kN | Used only for RFQ triage under clean axial loading; not a warranty or final catalog rating. | Internal Micro-RV preliminary specification. |
| Continuous axial load screen | <=100 N | 100-300 N requires load-spectrum review. Above 300 N should resize or move to a larger package. | Conservative engineering screen from internal data. |
| Stroke screen | <=50 mm | Longer travel increases buckling sensitivity, critical-speed risk, and alignment sensitivity. | Micro package design rule; verify by application geometry. |
| Speed screen | <=1,500 RPM | Higher speed needs heat, lubricant shear, preload torque, and motor integration review. | Conservative calculator boundary for this page. |
| Precision grade | G3 to G5 | Lead accuracy and axial play are disproportionately difficult to control at 1.5 mm. Specify only the grade absolutely required. | Manufacturing capabilities analysis (2026). |
| Positioning target | Drawing-specific, often <5 um backlash target | Preload improves backlash but increases friction and temperature. Absolute zero backlash should not be specified unless needed. | Application-specific metrology requirement. |
Evidence
Public manufacturer pages support the general roller screw selection logic. Size-specific values for this 1.5 mm package are internal preliminary data and must be confirmed per project.
| Source | Supports | Confidence |
|---|---|---|
| SKF planetary roller screw product guidanceExternal manufacturer page; reviewed July 20, 2026 | General roller screw architecture, load-life selection practice, and the need to validate application conditions. | High for general roller screw principles; not size-specific to this 1.5 mm custom package. |
| Schaeffler roller screw product guidanceExternal manufacturer page; reviewed July 20, 2026 | Public manufacturer context for roller screw families and application-level selection. | High for category context; use internal drawings for the 1.5 mm geometry. |
| Internal Micro-RV preliminary specificationInternal preliminary design record; reviewed July 20, 2026 | 1.5 mm nominal diameter, 0.5 mm lead, preliminary C_a 0.8 kN, C_0a 1.2 kN, and G3/G5 accuracy options. | Medium until confirmed against project drawings, heat treatment, lubrication, and inspection records. |
| Engineering synthesis for micro-actuator packagingSite-authored engineering synthesis; reviewed July 20, 2026 | Compares standard planetary and inverted packaging logic for radial envelope, actuator stack length, lubrication access, and assembly complexity. | Medium. Use it for option screening, not as a substitute for a third-party test report or final actuator design review. |
| Public data gapDocumented limitation; reviewed July 20, 2026 | There is not enough public empirical data to claim >600 N continuous operation at this 1.5 mm package size. | High as a limitation. Treat high-load claims as engineering-review territory, not self-serve catalog selection. |
| Option | Best For | Tradeoff |
|---|---|---|
| 1.5 mm standard planetary roller screw | Extreme radial miniaturization with standard actuator architecture (rotating shaft or nut). | Highest manufacturing risk and narrowest validation window compared to larger diameter screws. |
| 1.5 mm inverted roller screw | Shortest actuator stack and frameless motor integration, where the screw sits inside the rotor. | More complex to assemble and lubricate, typically with shorter maximum stroke than standard planetary screws. |
| 2-3 mm micro roller screw | Loads above the 1.5 mm conservative envelope or strokes beyond 50 mm. | Larger envelope, but better margin for preload, heat, buckling, and manufacturability. |
| Micro ball screw | Lower load, lower cost, and smoother sourcing when life margin is modest. | Lower load density than a roller screw and may need a longer nut for the same force margin. |
Assumptions: 60-90 N intermittent axial load, <=10 mm stroke, guided jaw.
Screen: Usually within the continuous envelope if thermal duty is low and the jaw carries side load.
Next action: Send CAD section, cycle target, and gripping duty profile.
Assumptions: Short insertion stroke, sterilization-compatible lubricant, low backlash target.
Screen: Technically plausible, but validation must include lubricant, preload torque, and regulatory material constraints.
Next action: Start with prototype risk review before locking preload or material.
Assumptions: Low force, fine motion, high repeatability, and compact motor integration.
Screen: Strong fit when radial space is tightly constrained and load stays well below 100 N.
Next action: Request lead accuracy, backlash, and cleanliness requirements.
Assumptions: >50 mm stroke or sustained load above 100 N.
Screen: Not the default 1.5 mm use case; buckling, critical speed, and heat margin dominate.
Next action: Compare against 2-3 mm micro screw families.
Related paths
Use these pages to compare the 1.5 mm micro roller screw against larger packages, product families, engineering review, and manufacturing constraints.
| Risk | Impact | Control |
|---|---|---|
| Peak load mistaken for continuous capacity | Overheated preload, rapid wear, and misleading life estimates during qualification. | Use <=100 N for self-serve screening; require engineering review above 100 N and block above 300 N. |
| Side load or misalignment carried by the screw | Uneven roller contact, backlash drift, and early surface fatigue. | Use external guides and specify allowable radial/moment load separately from axial force. |
| Over-specified zero backlash | Unnecessary preload raises torque and heat in a package with little thermal mass. | Specify the real repeatability target first, then choose preload and inspection method. |
| Cleanroom or medical lubricant mismatch | Viscous drag, particle risk, or failed sterilization validation. | Qualify lubricant and material stack before final life testing. |
| Lubricant starvation in short-stroke cycles | Increased stick-slip, localized wear, and erratic backlash drift over time. | Specify low-viscosity or cleanroom grease, and program periodic full-stroke distribution cycles. |
| Long stroke at 1.5 mm diameter | Lower critical-speed margin and higher buckling risk. | Resize to a larger package when stroke exceeds 50 mm or axial forces increase. |
No. Treat this page as a technical screening page for a custom 1.5 mm micro roller screw. Final dimensions and ratings require drawings and inspection records.
The package is extremely small, so preload heat, lubrication, and alignment can dominate the theoretical load rating. The calculator is built for RFQ triage, not final design release.
Possibly, but not as a self-serve continuous-duty assumption. Above 100 N needs duty-cycle and thermal review; above 300 N should usually resize or move to a larger package.
The page uses a simplified L10-style life screen from preliminary dynamic capacity, axial load, speed, lead, and stroke. It excludes shock, contamination, side load, and preload heat.
No. The screw should be treated as an axial transmission element. Rails, bushings, or a guided carriage must carry radial and moment loads.
Choose the larger family when load exceeds the conservative 1.5 mm envelope, stroke is longer than 50 mm, or the actuator needs more thermal and preload margin.
It can be investigated with preload and precision grinding, but the right target depends on repeatability, torque budget, lubricant, and inspection method.
Send axial load, stroke, speed, duty cycle, life target, packaging envelope, backlash or repeatability target, lubricant constraints, and any sterilization or cleanliness requirements.
No. It is a preliminary package target. Final outer diameter depends on thread form, roller count, preload, material, heat treatment, and how the nut interfaces with the actuator.
Only after project-specific material, cleanliness, sterilization, biocompatibility, and regulatory validation. This page does not claim medical approval.
A custom micro roller screw commonly needs a drawing review, process setup, grinding, inspection, and life test planning. Exact timing should be quoted after specs are confirmed.
Keep the result as a prototype-review signal. Send the load spectrum and CAD package so the design can be checked for heat, preload, stroke, and alignment risks.
Include axial load, stroke, speed, duty cycle, life target, packaging envelope, backlash or repeatability target, guide structure, lubricant restrictions, and any cleanroom, sterilization, or material constraints.
Inquiry Email
Please include screw type, diameter, lead, stroke, load, drawings, STEP files, and quantity timeline.
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