MOLD MATERIALS MAKING THE MOST OF HIGH—PERFORMANCE
Understanding high conductivity alloys and optimizing their use can help you build better molds.
By Douglas Veitch, Director, Brush Wellman
Injection molders and blow molders can benefit from high conductivity alloys by achieving faster cycle times and better part quality. There are certain properties of the mold material and polymer that enable these efficiencies to be realized. Once these characteristics are understood, mold builders can optimize their use of high-performance materials to provide a durable, fast-cycling mold for their customers.
Mold Alloy Thermal Properties
Some characteristics of mold materials enable us to better understand the thermal process that occurs while molding. Three important properties are:
1. Thermal Conductivity
Higher thermal conductivity equates to the transfer of more thermal energy per unit of time under steady state conditions.
2. Thermal Diffusivity
Higher thermal diffusivity means that thermal equilibrium will be reached faster when the temperature changes. A good thermal diffuser will react more quickly to environmental temperature changes.
3. Thermal Effusivity (conductivity divided by the square root of the diffusivity)
Higher thermal effusivity is a measure of the material’s efficiency at instantly removing heat from an object at a higher temperature with which it suddenly makes contact (see Chart 1).