To run a Cool analysis, all mold model surfaces must be defined with a mold material. This allows an accurate estimate of cooling rates in the design, using the properties associated with that mold material.
Cooling system performance is affected by how quickly heat moves from the plastic part to the mold cavity surface. This is affected by the material properties, the difference between melt and mold surface temperature, and the quality of the contact between the cooling plastic and the mold material.
Cooling system performance is also affected by the transfer of heat through the mold material to the coolant channels. Heat transfer is affected by turbulence in the coolant as it flows through the mold material, by the coolant inlet temperature, the coolant properties and the coolant flow rate.
The thermal conductivity of a mold material is also important to the performance of a cooling system. The units for thermal conductivity are; watts per meter °Kelvin [W/mK] in the metric system, or, Btu per hour foot °Fahrenheit [(Btu/hr)/ft/F)] in US units. High values of thermal conductivity indicate that the material is a good conductor.
Some typical thermal conductivities for pre-defined mold materials are shown below:
| Mold Material | Conductivity W/m C | Specific Heat J/KgC | Density kg/m3 |
|---|---|---|---|
| Stainless Steel | 24 | 460 | 7800 |
| P20 Steel | 29 | 460 | 7800 |
| Low TC Copper Alloy | 90 | 420 | 8400 |
| Medium TC Copper Alloy | 160 | 420 | 8400 |
| Aluminum | 170 | 780 | 2800 |
| High TC Copper Alloy | 250 | 420 | 8400 |