Press fit tolerance selection guide
A checklist for interference fit tolerance, assembly force, surface roughness, and service reliability.
This guide is prepared for quick engineering review. Critical design decisions still require the relevant standard, supplier data, and engineering approval.
Problem / Objective
Too much interference can damage parts during assembly; too little can allow loosening in service.
Assumptions
- Shaft and hub materials stay elastic.
- Surface roughness and roundness are controlled.
- Thermal assembly or press force is planned.
Step by step method
- Define diameter and load transfer need.
- Choose a starting ISO fit family.
- Calculate minimum and maximum interference.
- Write assembly force or thermal assembly strategy.
- Review removal, service, and surface damage risk.
Common mistakes
- Treating nominal diameter as the tolerance range.
- Forgetting roughness reduces effective interference.
- Not checking stresses in thin-walled hubs.
Related calculators
Related glossary terms
Quick FAQ
Question: When is a press fit used?
It is used when a compact, backlash-free, slip-resistant connection is needed.
Question: What does thermal assembly provide?
Temporary expansion or contraction lowers assembly force.
Question: Which tolerance limit matters most?
Minimum interference matters for load transfer; maximum interference matters for assembly damage.
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Glossary
Interference
Interference is a core engineering term. Definition, usage notes, and a practical example.
Tolerance
Tolerance is a core engineering term. Definition, usage notes, and a practical example.
Clearance
Clearance is a core engineering term. Definition, usage notes, and a practical example.
GD&T
GD&T is a core engineering term. Definition, usage notes, and a practical example.