What is bearing internal clearance?

Internal clearance is the total distance through which one bearing ring can be moved relative to the other in the radial direction (radial clearance) or axial direction (axial clearance). It is measured before mounting and is critical for proper bearing function.

When should I use C3 instead of CN (Normal) clearance?

C3 clearance (greater than Normal) is used when the bearing operates at elevated temperatures, has a tight interference fit on the shaft, or both. The extra clearance compensates for thermal expansion and fit-induced reduction. C3 is common for electric motors and pumps.

How does temperature affect bearing clearance?

Temperature causes thermal expansion of bearing components. The inner ring typically heats more than the outer ring, reducing radial clearance. For high-temperature applications, select a larger clearance class (C3, C4, or C5) to ensure adequate operating clearance.

How does interference fit affect bearing clearance?

An interference fit on the shaft expands the inner ring raceway, reducing radial clearance. Similarly, an interference fit in the housing compresses the outer ring raceway. The clearance reduction depends on the magnitude of interference, bearing dimensions, and material. This is why bearings with interference fits often require C3 or greater clearance.

免費工程工具

軸承內部游隙計算器

根據 ISO 5753-1，依軸承內徑與游隙級別查詢滾動軸承的徑向內部游隙。涵蓋 C2、CN、C3、C4 與 C5 級別。

ISO 5753-1 徑向球軸承 C2 – C5

結果

徑向游隙範圍

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中游隙

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游隙級別

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使用的內徑範圍

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所選內徑的所有游隙級別

級別	最小值 (μm)	最大值 (μm)	中點值 (μm)

什麼是內部游隙？

軸承內部游隙是指一個軸承套圈相對於另一個套圈在徑向方向上可移動的總距離。ISO 5753-1 針對徑向滾動軸承對此進行了定義。

游隙以範圍（最小值至最大值）的形式，針對每個內徑分組與游隙級別進行規定。製造出的軸承實際游隙將落在該範圍內。

游隙級別

級別	說明	典型用途
C2	小於正常	精密主軸、低噪音應用
CN	正常（預設）	通用機械、標準條件
C3	大於正常	電動機、泵、高溫環境
C4	大於 C3	重過盈配合、高溫環境
C5	大於 C4	極高溫度、大過盈配合

配合與溫度的影響

安裝後（運轉時）的游隙總小於未安裝時的游隙，原因如下：

過盈配合 — 軸配合會使內圈膨脹，從而減少游隙
溫度 — 內圈溫度通常高於外圈

實務範例

範例 — 軸承 6210，內徑 Ø50 mm，C3 級

已知： d = 50 mm，游隙等級 = C3

根據 ISO 5753-1 表格（內徑範圍 40–50 mm）：

C3 游隙： 20 – 43 μm

中間值：(20 + 43) / 2 = 31.5 μm

⚠️ 注意： 此表格適用於徑向球軸承（深溝球、角接觸）。滾子軸承、調心滾子軸承及球面滾子軸承依據 ISO 5753-1 擁有不同的游隙表格。