6. Conclusion
Conventionally drilled channels in tooling are not capable of achieving optimal geometries for complex impression shapes in a balanced fashion. In order to overcome these short falls additive manufacturing is currently being adopted to manufacture conformal cooling channels. Whilst significantly increasing performance, the design of these cooling channels is often time intensive and are still restricted by design rules required to minimise uneven cooling. To overcome these limitations new conformal cooling layers with self-supporting lattice structures are introduced. The lattices are constructed from simple unit cells and designed with self-supporting angles for AM. The effectiveness of the cooling layers was verified via experimental testing and simulation. The lattice structures were found to increase heat transfer over circular channels due to increased interfacial surface areas and fluid vorticity. Simulations, which were verified by experimental data, showed significantly lower thermal gradients on the heated surface. The cooling layers are likely to find applications in high performance tooling were high heat transfer rates and/or thermal balancing is critical. Examples could include; injection moulding, blow moulding, extrusion and die casting. Compression testing revealed that the strength of the lattice structures will need to be carefully designed in order to prevent deflection in high pressure areas. The compression characteristics of the three lattice types were found to vary widely demonstrating how lattices could be used to tailor parts with a wide range of mechanical properties.
