How is the idealized press-fit force calculated?

For the stated same-material solid-shaft/thick-ring elastic model, interface pressure is obtained from Lamé compliance and sliding force is F = p × π × d × L × μ. The fitted-ring outer diameter must describe that ring itself, not the overall outside diameter of an assembled rolling bearing.

What friction coefficient should I use?

Use a coefficient validated for the actual material pair, surface finish, lubricant, speed and contact pressure. The calculated force is directly proportional to μ, so a generic oiled or dry label is not sufficient for press sizing.

What does the thermal result mean?

The tool reports only the theoretical temperature rise δ/(αd) that expands the bore by the stated diametral interference. It contains no assembly clearance or thermal-loss allowance. Follow the component or bearing manufacturer’s mounting method and temperature limits.

Can this estimate size a press by itself?

No. The model assumes uniform elastic contact and constant sliding friction and omits entry geometry, static breakaway, misalignment, roughness, plasticity and edge effects. Press selection requires an engineering allowance supported by the actual process and equipment documentation.

Kan pressning skada lagret?

Ja, om kraft appliceras genom fel ring. När du pressar på en axel, applicera kraft ENDAST på innerringen. När du pressar in i ett hus, applicera kraft ENDAST på ytterringen. Överför aldrig kraft genom rullkroppar.

Gratis tekniskt verktyg #058

Kalkylator för presspassningskraft i lager

Estimate axial sliding force for an idealized same-material solid shaft and thick-walled fitted ring. This is a Lamé-model estimate, not a bearing-manufacturer mounting-force value.

Lamé-ekvationerMonteringskraftKallpress

Nominell borrning d (mm)

Diametral interferens δ (mm, t.ex. 0,018)

Kontaktlängd (mm, lagerbredd)

Fitted Ring Outer Diameter D_r (mm, ring material boundary; not bearing OD)

Sliding Friction μ (validated for the actual interface)

Youngs modul E (GPa; same material for shaft and ring)

Thermal Expansion α (μm/(m·K), e.g. 11.7)

Snabbförinställningar

Model boundary: valid only for a uniform elastic interference fit between a solid shaft and a concentric thick-walled ring of the same isotropic material under the simplified open-ended Lamé model. Real rolling-bearing rings, hollow shafts, dissimilar materials, short contacts and nonuniform geometry require manufacturer calculation or FEA.

Resultat

Press-Fit-kraft

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Gränssnittstryck p

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Equivalent tonne-force

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Theoretical Minimum Temperature Rise

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Gränssnittstryck (Lamé)

Press-Fit-kraft

μ — validated sliding-friction coefficient for the actual interface
δ — diametral interference (shaft OD − ring bore)
d — nominal interface diameter
D_r — actual outer material boundary of the fitted thick ring, not overall bearing OD
E — Young’s modulus shared by shaft and ring in this special-case equation

Alternativ för varmmontering

ℹ️ The thermal result is only ΔT_min = δ/(αd), the uniform temperature rise that expands the bore by exactly the interference. It provides zero assembly clearance and ignores heat loss to the shaft. Add an engineered clearance allowance and follow the component manufacturer’s permitted heating method and temperature limit.

Praktiskt exempel

Worked example — idealized ring geometry, δ = 0.018 mm

k = 50/80 = 0,625

p = 210000 × 0.018 / (2 × 50) × (1 − 0.625²) = 23.03 MPa

F = 23.03 × π × 50 × 18 × 0.10 / 1000 = 6.51 kN (0.66 tf)

⚠️ Kritiskt: När du pressar ett lager på en axel, applicera kraft ENDAST på innerringen. Överför aldrig kraft genom rullkropparna – detta kommer att orsaka brinellskador.