The coefficient of thermal expansion tells you how much a material grows per degree of temperature rise. This chart lists values for common engineering materials.
| Material | x10^-6 per C | x10^-6 per F |
|---|---|---|
| Carbon steel | 12 | 6.7 |
| Stainless steel (304) | 17 | 9.6 |
| Cast iron | 11 | 6.1 |
| Titanium | 8.6 | 4.8 |
| Copper | 17 | 9.4 |
| Brass | 19 | 10.6 |
| Bronze | 18 | 10.0 |
| Aluminum | 23 | 12.8 |
| Magnesium | 26 | 14.5 |
| PEEK | 47 | 26 |
| Polycarbonate | 68 | 38 |
| ABS | 90 | 50 |
| Nylon | 80 to 100 | 45 to 55 |
| Acetal (Delrin) | 110 | 61 |
| PTFE | 135 | 75 |
| UHMW | 150 to 200 | 85 to 110 |
Plastics move far more. Plastics expand roughly ten times as much as steel. Designs that mix metals and plastics, or that see wide temperature swings, must allow for the difference in fit and clearance.
FAQ
Why does thermal expansion matter in mechanical design? Parts made from different materials expand and contract at different rates as temperature changes, so a design that clamps or fits parts tightly at room temperature can bind, crack, or loosen at temperature extremes if differential thermal expansion isn’t accounted for in tolerances and fits.
See the Thermal Expansion Calculator and the Material Density Chart.
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