Estimate the screening ISO housing fit for a bearing seat, then use the report below to check material expansion, bore form, inspection evidence, and RFQ next steps.
Estimate a screening ISO housing fit for an actuator bearing seat. This does not replace the bearing manufacturer table or drawing-level GD&T review.
Supported quick-check range: 10-300 mm.
Ready for a fit check
Enter bearing outside diameter, load condition, and housing material to view the recommended screening class and RFQ next step.
Vibration and micro-motion in loose fits strip the housing bore, causing fretting corrosion and housing wear. Bearing supplier fit tables typically push rotating outer-ring, shock, or vibration cases toward transition or interference housing fits.
Aluminum's CTE (~24 µm/m-°C) is twice that of steel bearings (~12 µm/m-°C). An H7 fit at 20°C can degrade to a slipping clearance fit as temperature rises. For high-temp aluminum actuators, confirm maximum service temperature before choosing a tighter initial fit or steel sleeve.
ISO 1101 / ASME Y14.5 style controls are needed for bore form, shoulder perpendicularity, and datum location. A pass/fail bore diameter check alone does not prove the bearing ring is supported without distortion.
Use the calculator for first-pass routing, then use these conclusions to decide what must be proven on the drawing, quote, and inspection plan.
H7 is usually a screening start for stationary outer rings, while vibration, rotating outer-ring load, or shock often pushes the design toward transition or interference fits.
Evidence: SKF bearing interface guidance, reviewed July 4, 2026.
Aluminum CTE is roughly double bearing steel, so an interference fit confirmed at 20°C can lose retention at elevated service temperature.
Evidence: Engineering ToolBox CTE ranges, reviewed July 4, 2026.
Diameter alone does not control taper, ovality, cylindricity, shoulder squareness, or bore-to-mount alignment. RFQs should include GD&T and inspection evidence.
Evidence: ISO 1101 / ASME Y14.5 drawing-language references.
The calculator only chooses a first-pass direction. The report layer then explains which evidence must be checked before a bearing housing drawing is released or quoted.
Selecting the right ISO tolerance zone is critical for actuator longevity.
Application: Stationary outer rings. Easy assembly, standard for most industrial gearboxes and actuators.
Machining: Boring or precision reaming.
Application: Light indeterminate loads. High precision positioning where clearance must be virtually zero.
Machining: Precision CNC boring.
Application: Outer ring rotates or vibrates. Prevents fretting corrosion on the housing bore.
Machining: Fine boring, thermal shrink fit may be needed.
Application: Heavy shock loads, high-speed rotary actuators. Guarantees the bearing will not slip.
Machining: Press fit or thermal expansion assembly.
| Material | Density | Expansion | Machinability | Cost |
|---|---|---|---|---|
| 6061-T6 Aluminum | 2.70 g/cm³ | 23.6 µm/m-°C | Excellent | 1.2x |
| Cast Iron (FC250) | 7.20 g/cm³ | 10.5 µm/m-°C | Good | 1.0x (Baseline) |
| 304 Stainless Steel | 7.93 g/cm³ | 17.2 µm/m-°C | Fair | 2.5x |
| Carbon Steel (1045) | 7.85 g/cm³ | 11.5 µm/m-°C | Good | 1.4x |
* Note: When using Aluminum housings with Steel bearings, the high thermal expansion coefficient (23.6 µm/m-°C) means the housing bore will grow significantly faster than the bearing. Ensure your fit class accounts for the maximum operating temperature.
The data and engineering principles provided on this page are a screening layer compiled from public standards landing pages, bearing supplier guidance, and typical material-property references. Use them to prepare an RFQ, not to release a safety or production drawing without engineering approval.Public-source review date: July 4, 2026
| Claim | Traceable source | Use | Limit |
|---|---|---|---|
| ISO 286 is the traceable basis for IT tolerance language.Reviewed July 4, 2026 | ISO 286-1 standards landing page | Use for IT5/IT6/IT7 terminology and limits-and-fits language before converting to a full tolerance table. | The calculator uses simplified screening widths only; purchase the standard or use a verified table for released drawings. |
| Bearing supplier fit tables must govern final shaft and housing fits.Reviewed July 4, 2026 | SKF bearing interface / resultant fits guidance | Use to decide whether load direction, ring rotation, vibration, and retention risk require transition or interference fit. | Manufacturer catalog, bearing series, internal clearance, assembly force, and thermal case still override this page. |
| Aluminum thermal growth can reduce bearing retention in hot actuator duty.Reviewed July 4, 2026 | Engineering ToolBox linear thermal expansion table | Use the CTE mismatch as a screening trigger for steel sleeves, tighter initial fit, or operating temperature disclosure. | Actual CTE varies by alloy, temper, temperature band, and supplier certificate. |
| Bore form, orientation, and location need explicit drawing controls.Reviewed July 4, 2026 | ISO 1101 / ASME Y14.5 standards landing pages | Use for cylindricity, perpendicularity, and datum references on the actuator bearing housing RFQ. | Do not rely on diameter inspection alone for high-speed or preloaded bearing seats. |
| Traceable source | How to use it |
|---|---|
| ISO 286-1: ISO code system for tolerances on linear sizes | Traceable standards page; full tolerance values require the current paid standard or an approved table. |
| SKF bearing interfaces and resultant fits guidance | Public bearing-supplier guidance for fit selection and resultant fit risk. |
| ISO 1101 geometrical tolerancing | Reference for GPS geometrical tolerancing used to control bore form and orientation. |
| ASME Y14.5 dimensioning and tolerancing | Common RFQ drawing-language reference for datum, form, orientation, and location tolerances. |
| Engineering ToolBox: linear thermal expansion coefficients | Public engineering table used for CTE screening ranges; material certificates and operating temperature still govern final calculations. |
These are the most common ways a bearing housing RFQ can pass a simple diameter check but fail in sourcing, assembly, or service.
| Risk | Trigger | Impact | Mitigation |
|---|---|---|---|
| Misuse risk | Selecting H7 from the calculator without checking ring rotation. | Outer ring creep, fretting corrosion, bore wear, and bearing heat can appear after launch. | Confirm ring rotation and load direction against the bearing supplier table before freezing the drawing. |
| Cost risk | Specifying IT5, P7, or very low Ra without a functional reason. | Secondary honing, jig grinding, controlled temperature inspection, and scrap risk can dominate unit cost. | Use the loosest fit and form tolerances that still preserve bearing life and assembly retention. |
| Scenario mismatch | Using aluminum housings near hot motors, brakes, or high-duty gear sets. | Thermal growth can reduce interference and let the bearing seat slip under vibration. | Provide maximum operating temperature and evaluate steel inserts, steel housings, or revised fit class. |
| Inspection gap | Requesting only bore diameter and skipping cylindricity/runout. | A nominally in-tolerance diameter can still distort the bearing ring and shorten life. | Add CMM or roundness inspection for bore axis, shoulder perpendicularity, and datum relationship. |
Keep this page focused on actuator bearing housing fit and retention decisions; use the links below for adjacent but distinct sourcing questions.
The bearing housing is the structural component of an actuator that locates and supports the bearings, which in turn support the rotating shaft or lead screw. It ensures the shaft remains aligned under load.
If the housing bore is too loose (e.g., H8 or H9), the bearing outer ring may creep or spin, causing fretting corrosion and housing wear. If it is too tight (e.g., P6), it can compress the bearing outer ring, eliminating internal clearance and causing the bearing to overheat and seize.
Aluminum expands at roughly twice the rate of steel. At elevated operating temperatures, an aluminum housing bore will grow faster than the steel bearing outer ring, turning an interference fit into a clearance fit. A tighter initial fit or a steel insert sleeve is often required.
Avoid treating H7 as a default when the bearing outer ring rotates relative to the load, the actuator sees shock or vibration, or the housing is aluminum in hot service. Those cases need the bearing manufacturer fit table and often a transition or interference fit review.
Include bearing part number, housing bore nominal size and fit class, bore depth, shoulder perpendicularity, cylindricity or roundness, surface finish, datum scheme, material condition, coating or masking requirements, and expected operating temperature.
No. It is a quick screening tool using simplified IT7-width ranges. Released drawings should use the current ISO 286 data, the bearing manufacturer catalog, or customer-approved tolerance tables.
We use CNC fine boring bars rather than standard drills or end mills. This guarantees high circularity (roundness) and cylindricity, ensuring the bearing is supported uniformly across its entire width.
Yes, split bearing housings (plummer blocks) are machined by first assembling the two rough halves with locating pins and bolts, and then boring the bearing seat in a single operation to ensure perfect concentricity.
A two-point bore gauge can miss taper, lobing, cylindricity error, and bore-axis misalignment. High-duty actuator housings should add CMM, roundness, or air-gauge evidence where bearing life depends on form control.
Define whether the bearing seat is masked or finished after coating. Anodize buildup or plating thickness can change the effective bore size and surface texture enough to alter the selected fit.
Send the 2D drawing, bearing part number, CAD model, material and finish requirement, operating temperature, and annual volume for engineering review before releasing the RFQ to production.
Send us your 3D CAD files or 2D drawings. Our engineers will review your ISO fit requirements and provide a quote within 24 hours.
Inquiry Email
Include drawings, material, finish, tolerances, quantity, and delivery location.
