The design of conformal cooling channels in injection molding tooling

Solid Freeform Fabrication technologies have demonstrated the potential to produce tooling with cooling channels, which are conformal to the molding cavity. 3D Printed tools with conformal cooling channels have demonstrated simultaneous improvements in production rate and part quality as compared with conventional production tools. Conformal cooling lines of high performance and high complexity can be created, thus presenting a challenge to the tooling designer. A systematic, modular approach to the design of conformal cooling channels is presented. Cooling is local to the surface of the tool, so the tool is divided into geometric regions and a channel system is designed for each region. Each channel system is itself modeled as composed of cooling elements, typically the region spanned by two channels. Six criteria are applied, including: a transient heat transfer condition, which dictates a maximum distance from mold surface to cooling channel; considerations of pressure and temperature drop along the flow channel; and considerations of the strength of the mold. These criteria are treated as constraints, and successful designs are sought that define windows bounded by these constraints. The methodology is demonstrated through application to a complex core and cavity for injection molding.