KEVOS® MAKEOS · Strength
Press and Shrink Fit Pressure and Holding Torque
What contact pressure, hub stress and holding torque does this interference give?
Interface pressure of a hub on a solid or hollow shaft from the diametral interference (Lamé), hub bore stresses, torque and axial holding capacity, and the hub temperature rise for a shrink fit.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Interface diameter | mm | Nominal diameter of the fit. |
| Hub outside diameter | mm | Outside diameter of the hub around the fit. |
| Shaft bore (0 = solid) | mm | Bore of a hollow shaft; 0 for solid. |
| Diametral interference | mm | Shaft diameter minus hub bore diameter; use the minimum for holding capacity and the maximum for stress. |
| Engagement length | mm | Length of the fitted contact. |
| Coefficient of friction at interface | Friction coefficient for the assembled fit, from tests or your design guide (assembly method and surface finish affect it). | |
| Materials | ||
| Hub elastic modulus | GPa | Hub material modulus. |
| Hub Poisson’s ratio | Hub Poisson’s ratio. | |
| Shaft elastic modulus | GPa | Shaft material modulus. |
| Shaft Poisson’s ratio | Shaft Poisson’s ratio. | |
| Hub yield strength | MPa | Minimum yield strength of the hub material. |
| Required safety factor on hub | Factor of safety required by your design code, customer specification or company standard. | |
| Shrink fitting | ||
| Hub expansion coefficient | µm/(m·K) | Linear expansion coefficient of the hub material over the heating range. |
| Assembly clearance wanted when hot | mm | Extra clearance needed to slide the hot hub on (often about 0.001 × d). |
Method and formulas
- p = δ ÷ [d((D² + d²) ÷ (D² − d²) + νh) ÷ Eh + d((d² + di²) ÷ (d² − di²) − νs) ÷ Es].
- Hub hoop at bore σθ = p(D² + d²) ÷ (D² − d²); von Mises with σr = −p.
- Torque T = μ p π d² L ÷ 2; axial force F = μ p π d L.
- Temperature rise ΔT = (δ + clearance) ÷ (α d).
- Example: 0.04 mm interference on a 50 mm steel fit in a 100 mm hub gives p = 60 MPa and holds 2,120.6 N·m.
Limitations
- Elastic, plane-stress Lamé solution for equal-length hub and shaft; hub ends and keyways raise local stresses.
- Surface smoothing reduces effective interference on rough surfaces.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check gears, couplings and pulleys pressed on shafts
- Find the heating temperature for a shrink fit
- Compare interference with torque requirement
Who it is for
- Design engineers
- Structural and mechanical engineers
- Engineering students
What you get
- Interface pressure
- Hub hoop and von Mises stress at the bore
- Holding torque and axial force
- Hub temperature rise for shrink fitting
Interpreting the result
- Check holding capacity at minimum interference and hub stress at maximum interference.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 631–634. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Press and Shrink Fit Pressure and Holding Torque calculator
