Thermal conductivity of H13, P20, 1.2344 and other die steels, with the values that set cooling time in die casting and injection moulding — plus how conductivity translates into cycle time.
Complete reference tables and engineering data for die steel thermal conductivity reference. All values verified against ISO, ANSI, and manufacturer standards.
Published starting values are not measurements. They are recommendations, and they differ because each manufacturer optimises for something different — tool life, surface finish, chip control, or spindle power. Two suppliers can quote the same ISO grade and give you cutting speeds 30% apart, and each figure can be right for that supplier’s own geometry, edge preparation and coating.
That is why the number this calculator returns is a starting point, not a setting. Treat the catalogue figure as the middle of a band, then correct it on the first part: if the chips come off blue or the spindle load sits above roughly 80%, come down; if the finish is smeared and the chips are thin and stringy, come up. Write down what actually worked — that shop-specific number beats any published value.
Thermal conductivity determines how quickly heat moves through tool steel. High conductivity improves cooling efficiency in injection moulds (shorter cycle time) and reduces thermal stress in die casting dies. This reference compares common die steel grades.
Higher conductivity shortens cooling time, which is typically 50-70% of the total cycle. Switching from H13 (25 W/mK) to copper-beryllium inserts (120 W/mK) in hot spots can reduce cycle time 15-30%. The cost of copper-beryllium is justified when cycle time reduction exceeds the material cost premium.
During aluminium die casting, the die surface reaches 500-600 deg C. Higher conductivity spreads heat more uniformly, reducing hot spots that cause soldering (aluminium sticking) and heat checking (surface cracking). H13 with good water-line design is the standard solution; high-conductivity alloys are used for the most demanding areas.
There is generally an inverse relationship -- harder steels have lower conductivity. Annealed steel conducts heat better than hardened steel of the same grade. Carbide (hard but with higher cobalt) actually has decent conductivity (50-80 W/mK for WC-Co grades) because cobalt and tungsten carbide are both reasonable heat conductors.
Use this reference to select die and mould materials with appropriate thermal conductivity. For injection moulds, higher conductivity (P20, copper-beryllium) reduces cycle time. For die casting, H13 balances conductivity with high-temperature strength. Always prioritise the mechanical requirements (strength, hardness, wear) over conductivity.
Continue with closely related resources from the machining reference library.
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