Reducing ejection forces for parts moulded into direct metal laser sintered tools.

With the development and refinement of Rapid Prototyping technologies, a gradual move into tooling applications has occurred. However, the design principles that are traditionally applied to mould tools are not always suitable for use with layer-manufactured tools. As these technologies develop, so must the ways in which they are used. Tools produced using Direct Metal Laser Sintering (DMLS) have previously been shown to be suitable for several applications, in particular for plastic injection moulding. However, there has been little work undertaken on the best procedures to follow when designing tools made using the DMLS process. This work has been performed to determine the effect of layer thickness, level of finishing and draft angle on the forces required to eject parts from DMLS injection mould tools. Results show that, although the choice of layer thickness and the level of tool finishing have a substantial effect on the ejection forces required, the level of draft included does not show an obvious trend towards increasing or decreasing the force.