Thermal Expansion Calculator
Formula: ΔL = L₀ × α × ΔT (α in ppm/°C, i.e. 10⁻⁶/°C)
Common Material CTEs
| Material | α（ppm/°C） | Notes |
|---|---|---|
| Steel | 11.7 | |
| Aluminum Alloy | 23.1 | Highest, lightweight structures |
| Copper | 17 | Wire, heat sinks |
| Silicon (Si) | 2.6 | Semiconductor substrate |
| Stainless Steel 304 | 17.2 | General-purpose SS |
| Invar Alloy | 1.2 | Ultra-low expansion, precision instruments |
A precision aluminum fixture is designed at room temperature (25°C) but used in a heat-treatment furnace at 120°C. The engineer must calculate the fixture's thermal expansion to confirm part locating accuracy stays within tolerance at high temperature and avoid thermal distortion causing machining errors.
Aluminum alloy (α = 23.1 × 10⁻⁶/°C), fixture original length L₀ = 500 mm / Working ΔT = 120 - 25 = 95°C / Expansion: ΔL = L₀ × α × ΔT = 500 × 23.1×10⁻⁶ × 95 = 1.097 mm / With a locating tolerance of ±0.5 mm, 1.097 mm exceeds tolerance — compensation is required / Option: switch to Invar (α ≈ 1.2×10⁻⁶/°C): ΔL = 500 × 1.2×10⁻⁶ × 95 = 0.057 mm (within tolerance)
FAQFAQ
Related Tools
Temperature Converter
Thermal expansion requires the temperature delta ΔT; convert operating temperatures (°C/°F/K) to consistent units before applying the expansion formula.
Open toolLength Converter
Compare the calculated expansion (ΔL) against part tolerances, making sure both use the same length unit (mm, µm, or inch).
Open toolProcess Capability Index
Thermal expansion affects dimensional stability; in high-temperature or wide-ΔT processes, account for its impact on CPK and verify measurement temperature conditions.
Open tool