Why does thermal expansion matter for bearings?

When a shaft heats up during operation, it expands axially. If both bearings are fixed axially (locating), the expansion creates internal preload, increasing friction and temperature. Proper locating/non-locating arrangement allows thermal growth without damaging the bearings.

What is a locating/non-locating bearing arrangement?

In a locating/non-locating arrangement, one bearing is fixed axially (locating) to position the shaft, while the other bearing is free to slide axially (non-locating) to accommodate thermal expansion. This is the most common arrangement.

Which CTE value should I enter?

Use a mean linear CTE for the exact material grade over the actual temperature interval. CTE varies with composition and temperature; generic material-family values are only rough examples.

How much expansion is typical?

A 1-meter steel shaft with a 50°C temperature rise expands about 0.6 mm. This may seem small but can generate enormous forces if both bearing positions are axially fixed.

Does axial differential growth determine bearing fit or clearance?

No. Axial span growth helps size axial displacement capacity. Radial fit and bearing internal clearance require local diameters, ring/seat temperatures, material properties and the exact bearing arrangement.

Free Engineering Tool #054

Bearing Thermal Expansion Calculator

Calculate separate uniform axial thermal changes of shaft and housing and their signed difference. Enter actual lengths, mean CTE values and temperature changes.

δ = L × α × ΔTSigned Heating/CoolingNo Automatic Bearing Selection

Results

Shaft Axial Expansion δ_shaft

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Housing Axial Expansion δ_housing

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Differential Expansion

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Thermal Expansion Formula

L — effective initial span (mm)
α — mean linear CTE over the stated interval (μm/(m·K), numerically ×10⁻⁶/K)
ΔT — signed temperature change from the reference state (K or °C difference)

CTE input

CTE is material-grade and temperature dependent. Obtain a mean value over the actual interval from controlled material data rather than choosing a broad material-family label.

Locating / Non-Locating Arrangement

ℹ️ A locating/non-locating support can accommodate axial displacement from relative shaft/housing thermal growth, but required travel and bearing type must be selected from the complete arrangement loads, fits, tolerances and manufacturer data.

The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.