Calculator Inputs
Use the measured tolerance limits to estimate pressure, holding force, torque capacity, heating needs, and inspection suitability.
Example Data Table
This sample inspection set uses the default values preloaded in the calculator.
| Batch | Nominal Diameter | Hole Range | Shaft Range | Interference Range | Pressure Range | Torque Range | QC Note |
|---|---|---|---|---|---|---|---|
| QC-IF-001 | 50.000 mm | 49.970 to 49.985 mm | 50.010 to 50.025 mm | 25.00 to 55.00 µm | 39.89 to 87.75 MPa | 1127.75 to 2481.05 Nm | Suitable sample for controlled press fit review. |
Formula Used
This calculator uses a cylindrical press fit model with elastic shaft and hub behavior. It is suitable for preliminary quality control checks where the fit is axisymmetric and surfaces are reasonably uniform.
Δd = dshaft − dhole
C = (1 − νs2) / Es + ((1 − νh2) / Eh) × ((Do2 + d2) / (Do2 − d2))
p = Δd / (d × C)
F = μ × p × π × d × L
T = μ × p × π × d2 × L / 2
ΔT = (Δdmax + ca) / (α × d)
For slotted hubs, plastic deformation, rough surfaces, lubrication changes, or tapered joints, detailed design review or test data is recommended.
How to Use This Calculator
- Enter the nominal interface diameter and the measured or specified hole and shaft tolerance limits in millimeters.
- Provide fit length, hub outer diameter, and the material properties for both components.
- Enter the friction coefficient and any required assembly clearance for thermal fitting.
- Optionally add acceptance criteria such as target interference, pressure limit, torque demand, or axial force demand.
- Press the calculate button to show results above the form, directly below the header.
- Review the graph, detailed table, and acceptance checks before deciding whether the batch passes inspection.
- Use the CSV or PDF buttons to export the calculated results for reporting or shop floor documentation.
FAQs
1. What is an interference fit?
An interference fit occurs when the shaft diameter is larger than the hole diameter before assembly. Pressing or heating creates surface pressure that resists motion and transmits torque or axial load.
2. Why use minimum and maximum diameters instead of one size?
Quality control decisions depend on tolerance limits, not only nominal dimensions. Using min and max sizes shows the worst and best possible combinations across a production batch.
3. Why can minimum pressure become zero?
If the tolerance ranges overlap, some assemblies may have line contact or clearance instead of positive interference. In that case, the minimum predicted contact pressure drops to zero.
4. What does hub outer diameter change in the result?
A thicker hub is usually stiffer and can sustain more pressure for the same interference. A thin hub expands more easily, reducing contact pressure and holding capacity.
5. How is the heating temperature estimate calculated?
The tool estimates the temperature rise needed to expand the hub bore by the maximum interference plus the extra assembly clearance you requested. It uses the hub thermal expansion coefficient.
6. Can I use different materials for shaft and hub?
Yes. Enter separate modulus and Poisson ratio values for the shaft and hub. This helps the calculator reflect the stiffness difference between unlike materials.
7. Does friction strongly affect torque and axial holding force?
Yes. Friction directly scales the load transfer capacity. Lower friction reduces both torque and axial retention, even when the interference and contact pressure stay unchanged.
8. What usually causes a QC fail?
Typical issues include insufficient minimum interference, excessive maximum pressure, weak minimum torque capacity, or weak axial retention against the stated acceptance limits.