SLM tooling for die casting with conformal cooling channels

The paper reports an experimental study of die-casting dies with conformal cooling fabricated by direct-metal additive techniques. The main objective is to compare the benefits and limitations of the application to what has been widely discussed in literature in the context of plastics injection molding. Selective laser melting was used to fabricate an impression block with conformal cooling channels designed according to part geometry with the aid of process simulation. The tool was used in the manufacture of sample batches of zinc alloy castings after being fitted on an existing die in place of a machined impression block with conventional straight-line cooling channels. Different combinations of process parameters were tested to exploit the improved performance of the cooling system. Test results show that conformal cooling improves the surface finish of castings due to a reduced need of spray cooling, which is allowed by a higher and more uniform cooling rate. Secondary benefits include reduction of cycle time and shrinkage porosity.