How is press-fit force calculated?

Press-fit force F = p × π × d × L × μ, where p is the interface pressure from Lamé's thick-cylinder equations, d is the bore, L is the contact length, and μ is the assembly friction coefficient (typically 0.08-0.15 with oil).

What friction coefficient should I use for assembly?

For assembly (pressing in), use μ ≈ 0.08-0.12 with oil lubrication on the shaft. Dry assembly uses μ ≈ 0.15-0.20. Always lubricate the shaft before pressing to reduce force and prevent scoring.

When should I use hot mounting instead of cold pressing?

Hot mounting (heating the bearing to 80-110°C) is recommended when: the interference is large (>0.001×d), the bearing bore exceeds 80mm, or the press-fit force exceeds the capacity of your press. Never heat above 120°C.

What press capacity do I need?

The press must provide at least 1.5× the calculated press-fit force to account for variations. For a typical 50mm bearing with normal interference, 5-20 kN (0.5-2 tonnes) is common. Larger bearings may require 50-100+ kN.

Can pressing damage the bearing?

Yes, if force is applied through the wrong ring. When pressing onto a shaft, apply force ONLY to the inner ring. When pressing into a housing, apply force ONLY to the outer ring. Never transmit force through rolling elements.

Free Engineering Tool #058

Bearing Press-Fit Force Calculator

Estimate the axial force required to cold press-fit a bearing onto a shaft. Uses Lamé’s thick-cylinder equations with assembly friction coefficient.

Lamé EquationsAssembly ForceCold Press

Results

Press-Fit Force

—

Interface Pressure p

—

Force in tonnes

—

Recommended Press Capacity

—

Hot Mounting Temperature

—

Interface Pressure (Lamé)

Press-Fit Force

μ — assembly friction: 0.08–0.12 with oil, 0.15–0.20 dry
δ — diametral interference (shaft OD − bearing bore)
d — nominal bore diameter
D_o — bearing outer diameter

Hot Mounting Alternative

ℹ️ Heating the bearing to 80–110°C expands the inner ring enough to slide onto the shaft without force. Required ΔT ≈ δ / (d × α) + 10°C margin. Never exceed 120°C to avoid metallurgical changes.

Practical Example

Example — 6210 (50×80×18), δ = 0.018 mm

k = 50/80 = 0.625

p = 210000 × 0.018 / (2 × 50) × (1 − 0.625²) = 23.3 MPa

F = 23.3 × π × 50 × 18 × 0.10 / 1000 = 6.6 kN (0.67 tonnes)

⚠️ Critical: When pressing a bearing onto a shaft, apply force ONLY to the inner ring. Never transmit force through rolling elements — this will cause brinelling damage.

Bearing Press-Fit Force Calculator | Lamé Equations | Free Online Tool

Published by admin on February 15, 2026 February 15, 2026

Results

Interface Pressure (Lamé)

Press-Fit Force

Hot Mounting Alternative

Practical Example