Hybrid Additive and Subtractive Manufacturing of Direct-Heated Tooling

Pre-heating is a common requirement for production tooling in applications such as compression and injection molding. While the carbon fiber reinforcements commonly used in large-area additive manufacturing improve the thermal conductivity of polymers, they are still far below that of metal tooling. This study presents a method for direct, local Joule heating of tooling without the need for additional heating elements. A current is induced in the composite tooling, resulting in resistance heating of the substrate. High conductivity material is locally embedded to achieve local control over the heating characteristics. Embedding of the conductive material is accomplished by selectively switching material compositions during the printing process. Demonstration tooling is produced using hybrid additive and subtractive manufacturing using an AMBIT XTRUDE in a HAAS machining center and evaluated with thermal imaging. Direct heating of tooling expands the potential applications of additive manufacturing by overcoming the challenges of low thermal conductivity materials.