SME
Manufacturing Processes · Problem type
Clearance, transition or interference?
Use this for “A 25.000–25.021 mm hole takes a 25.002–25.015 mm shaft. Which kind of fit is it?”
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The hole is 25.000–25.021 mm. What kind of fit does each shaft make?
Tap a card, then tap its group.
Compare the shaft’s largest size with 25.000 and its smallest size with 25.021: the signs of Cₘᵢₙ and Cₘₐₓ name the fit.
Assumptions
•
Every card pairs the same hole, 25.000–25.021 mm, with a shaft of the limits shown.
•
Cₘₐₓ is the largest hole minus the smallest shaft; Cₘᵢₙ is the smallest hole minus the largest shaft.
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A negative clearance is an interference: the shaft is bigger than the hole.
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Related lessons
Tolerances
Main lesson
Tolerance stack-up: worst case and RSS
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Process capability: Cₚ and Cₚₖ
Use this for “A shaft is 25.000 ± 0.030 mm. The process runs at a mean of 25.006 mm with σ = 0.008 mm. Find Cₚ, Cₚₖ and the share outside.”