Engineering · Calculator
Thermal expansion stack.
Predict assembly clearance and interference at operating temperature. Add up to 8 segments — each with its own length, material, and direction — and see total expansion at your operating temperature. Useful for cryo-to-hot ranges, satellite thermal cycles, and fits that need to survive process or operational temperature swings.
Temperature range
Reference and operating temperatures.
Reference T is typically the dimensioning temperature on the drawing (68°F / 20°C per ASME Y14.5). Operating T is where you need the part to function. Common ranges below.
Stack segments
Add segments along the dimension chain.
Use sign +/− on length to indicate direction along the chain. Up to 8 segments. Material list covers common aerospace, medical, and tooling alloys.
Result
ΔL = L₀ × CTE × ΔT, summed across segments. CTE values are room-temperature averages from MMPDS/aerospace handbooks. For wide ranges (cryo to high-T), real CTE varies — these results are first-order estimates.
Per-segment breakdown
| # | Material | L₀ | CTE | ΔL | L at op T |
|---|---|---|---|---|---|
| Add segments to see results. | |||||
When this matters
Where thermal stack drives design.
- Press fits at operating T: a steel pin in an aluminum housing tightens at cryo (Al shrinks more) and loosens at high T. Spec the interference at room T to survive the cold case.
- Optical mounts and metering structures: Invar 36 (CTE ≈ 0.7 ppm/°F) is used precisely because it doesn't move. Mixing Invar with aluminum across a long mount creates focus drift.
- Satellite shadow-cycle: +250°F sun side to −150°F shadow side every 90 min in LEO. Bimetallic stacks bow; matched-CTE stacks survive.
- Cryo plumbing (LOX, LH2): −297°F (LOX) and −423°F (LH2) shrink stainless ~3-4‰. Bellows or expansion loops are required, not optional.
- Turbine hot section: Inconel 718 at 1200°F grows ~0.8% per inch from room T. Blade-tip clearances are sized for the hot case, then verified at cold (assembly) state.
CTE values used here are room-temperature averages. For high-precision work spanning >500°F, use CTE-vs-T curves from the material vendor or MMPDS.
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