Interference Fit
Glossary · Threads & Fits
At a glance
- Category /
- Threads & Fits
- Also called /
- press fit, shrink fit
- Related /
- 4 terms
- Source /
- Written in the shop
An interference fit is one where the shaft is deliberately larger than the hole it goes into, so the two are held together by elastic pressure once assembled.
Also called: press fit · shrink fit
In practice
Assembly is by press, or by heating the outer part and cooling the inner one so it drops in and grips as temperatures equalise. The amount of interference is measured in thou and calculated from the diameters and materials.
Why it matters
A few thou decides whether a bearing race spins in its housing or cracks it. Interference fits are one of the places where machining to a tenth is genuinely justified rather than optional.
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