Shrink Fit Assembly

Calculate the exact temperature required to heat a housing (or cool a shaft) to achieve the necessary clearance for a shrink-fit assembly.

Assembly Fit Parameters
The amount the shaft is larger than the hole at room temp.
The extra space needed to smoothly assemble the parts.
Target Assembly Temperatures
Heat Housing To

--

°F
ΔT = +0°F
Or Cool Shaft To

--

°F
ΔT = -0°F
Total Dimensional Change Required: 0.000 in
Assembly Strategy

Shrink fitting creates an extremely strong mechanical joint without fasteners. You must expand the hole (housing) by heating it, OR shrink the pin (shaft) by cooling it.

The Mathematics

Total Growth Needed = Interference + Drop Clearance

$\Delta T = \frac{\text{Total Growth}}{\text{Dia} \times \text{CTE}}$
Cooling Medium Limits
Medium Imperial Metric
Standard Freezer0 °F-18 °C
Dry Ice (CO₂)-109 °F-78 °C
Liquid Nitrogen-320 °F-196 °C
Heating Warnings
  • Heating steel above 400°F (200°C) can begin to temper it, reducing its hardness.
  • Heating aluminum above 300°F (150°C) can ruin its artificial aging (T6 heat treatment).
  • If the required heat temp is too high, cool the shaft in liquid nitrogen *and* heat the housing slightly to combine the ΔT effects.