What is HDT (Heat Deflection Temperature)?

HDT is the temperature at which a material deforms by a specified amount under a standardised load (0.45 MPa for HDT-B). Above the HDT, printed parts will warp, sag, or lose structural integrity under load. It is more relevant than glass transition for load-bearing parts.

Can I increase the heat resistance of PLA?

Yes. Annealing PLA in an oven at 80-110°C for 1-2 hours can increase its HDT to 80-120°C by crystallising the polymer. However, parts shrink 2-5% during annealing and may warp, so design with shrinkage compensation.

Why does PLA warp in cars?

Car dashboards can reach 60-80°C in direct sunlight. This exceeds PLA HDT of 55°C, causing the part to soften and deform under its own weight. Use PETG (75°C HDT), ABS (95°C), or ASA (95°C) for automotive applications.

What material has the highest heat resistance?

Among common FDM materials, Polycarbonate (PC) has the highest HDT at ~130°C. For extreme temperatures, consider PEEK (250°C HDT) or PEI/ULTEM (170°C), though these require specialised high-temperature printers.

3DPrintCalcs

Heat Resistance Calculator — Operating Temperature Check

Check if your printed part will withstand a given operating temperature.

Material

Operating Temperature

Load-Bearing?

Exposure Duration

How We Calculate This

Heat Resistance Assessment

Effective limit = HDT (load-bearing) or Glass transition (no load)
Safety margin = Effective limit - Operating temp - Safety buffer
Safety buffer: 15°C continuous, 10°C intermittent, 5°C brief

Load-bearing parts use the HDT, which is lower than the glass transition temperature. Non-load-bearing parts can operate closer to the glass transition. The safety buffer accounts for hot spots and temperature fluctuations.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.