Why is correct bearing fit important?

Correct bearing fit ensures the ring with rotating load has an interference fit to prevent creep (ring rotation on the seat), while the non-rotating ring has a looser fit for easy mounting and to allow axial float if needed.

What is a rotating inner ring load?

Rotating inner ring load is the most common case — the shaft rotates and the housing is stationary. The inner ring needs a tight (interference) fit on the shaft, and the outer ring gets a sliding or transition fit in the housing.

What tolerance zone should I use for a shaft?

For rotating inner ring load with normal conditions: j5 or k5 for light loads on ball bearings, k5 or m5 for normal loads, m6 or n6 for heavy loads or vibrations. The tighter the fit, the more force required for mounting.

What is the difference between transition and interference fit?

A transition fit (e.g., j5, k5) may result in either slight clearance or slight interference. An interference fit (e.g., m5, n6, p6) always results in the shaft being larger than the bore, requiring force or heating for assembly.

When should I use a loose housing fit?

A loose housing fit (e.g., H7, G7) is used when the outer ring must be free to move axially (non-locating bearing position), when the housing is split, or when the outer ring load is stationary (rotating shaft, fixed housing).

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軸承配合與公差選擇

根據軸承製造商目錄指南，使用 ISO 286 公差系統，為滾動軸承安裝選擇推薦的軸與軸承座公差帶。選擇負荷類型與軸承內徑。

ISO 286 軸與軸承座配合公差帶

軸承內徑 (mm)

載荷條件

軸承類型

軸向位置

快速預設

建議配合

軸公差帶

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軸承座公差帶

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配合類型 — 軸

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配合類型 — 軸承座

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安裝注意事項

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一般原則

承受旋轉負荷的套圈應採用過盈配合以防止蠕變。承受固定負荷的套圈可採用較鬆的配合，以利安裝與軸向位移。

軸配合建議（旋轉內圈）

負荷	球軸承	滾子軸承	配合類型
輕載 / 方向變化	j5, j6	j5, j6	過渡配合
一般	k5, k6	m5, m6	過渡配合 / 輕度過盈
重載 / 衝擊	m5, m6	n6, p6	過盈配合

軸承座配合建議（固定外圈）

條件	定位	非定位	配合類型
一般負荷	J7, H7	H7, G7	滑動 / 過渡
重載	K7, M7	H7, J7	過渡配合
輕載，易於拆卸	H7	G7, F7	間隙
外圈旋轉	M7, N7	K7, M7	過盈配合

ℹ️ 提示： 對於內徑 d > 100 mm 的軸承，由於相對過盈量較小，通常建議採用更緊的公差等級。空心軸也需要更緊的配合。

⚠️ 注意： 這些是一般建議。請務必根據您的應用，參照特定軸承製造商（SKF、FAG/Schaeffler、NSK、Timken）的指南進行驗證。