FREE ENGINEERING TOOL
Thermal Expansion Calculator
Plastics expand 5–6 times more than steel — on a PC sight window, an acrylic panel or a POM structural part, the dimensional shift from temperature changes can exceed the tolerance itself. Pick a material, enter the base dimension, and get the dimension at any temperature, the full-year size range, machining temperature compensation, and the fit-up difference against a metal frame. Everything is computed locally in your browser — no sign-up required.
Common parameters
Coefficients are industry-typical values; grades, fillers and orientation change them. For precise work use the datasheet of your exact grade, or enter a measured value.
① Dimension at any temperature
Dimension at T
— mm
Change vs. reference
— mm
Change per meter
— mm/m
About this tool
Temperature is a critical variable in precision plastics machining. This calculator was developed in-house at Cremage and is used on our production floor for machining and inspection. Our customers’ design engineers found it useful, so we opened it up — we hope it helps you too. Results are for reference only; for final design, rely on your grade’s datasheet and actual measurements.
© Wuxi Cremage Technology Co., Ltd. All rights reserved.
Typical thermal expansion coefficients of common plastics
| Material | Abbreviation | α typical | Common range | vs. steel |
|---|---|---|---|---|
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Unit: ×10⁻⁶/°C (mm/m·°C). Values are industry-typical for unfilled materials; fillers such as glass fiber significantly lower them. Your grade’s datasheet governs.
Formula and notes
L(T) = L₀ × ( 1 + α × (T − T₀) )
where α is the linear thermal expansion coefficient. The fit-up difference between sheet and frame ≈ L × (α(sheet) − α(frame)) × ΔT; when it exceeds the reserved clearance, the sheet bows out of plane — bow height follows from the arc-vs-chord geometry.
Notes: ① coefficients are typical values — exact figures come from your grade’s datasheet; ② the calculation is a uniform-temperature linear compensation and does not include cutting heat or clamping stress; ③ soak parts and gauges together for precision measurement.