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.

免費工程工具 #054

軸承熱膨脹計算器

分別計算軸與軸承座的均勻軸向熱變化及其帶正負號的差值。輸入實際長度、平均熱膨脹係數 (CTE) 數值與溫度變化。

δ = L × α × ΔT帶正負號的加熱/冷卻無自動軸承選型

結果

軸軸向膨脹 δ_shaft

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軸承座軸向膨脹 δ_housing

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差動膨脹

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熱膨脹公式

L — 有效初始跨距 (mm)
α — 指定區間的平均線膨脹係數 (μm/(m·K)，數值上為 ×10⁻⁶/K)
ΔT — 相對於參考狀態的帶正負號溫度變化 (K 或 °C 差值)

線膨脹係數輸入

線膨脹係數取決於材料等級與溫度。請從受控材料資料中取得實際區間的平均值，而非選擇廣泛的材料類別標籤。

定位 / 非定位配置

ℹ️ 定位/非定位支撐可容納因軸/軸承座相對熱膨脹產生的軸向位移，但所需的行程與軸承類型必須根據完整的配置負荷、配合、公差與製造商資料來選擇。