Development of a New Production Process for Thermally Conductive Resin for Additive Manufacturing Using mSLA Process

Injection molding tools are characterized by high costs, due to the use of expensive materials such as aluminum or tool steel, and the lengthy production process involving machining. This greatly limits the economic viability of using metal molds for producing small series, and even more so for rapid prototyping. Additive manufacturing processes, such as masked stereolithography (mSLA), enable the production of molds from polymers providing short production time and good accuracy. However, injection molds manufactured using mSLA using conventional resins suffer from long cooling times and lower strength. This contribution presents a new approach that significantly overcomes these disadvantages by developing and characterizing a novel composite material. To this end, aluminum oxide ceramic particles will be incorporated into a photopolymer resin. Various additives will also be employed to optimize the processability and printability of the newly developed material. This should enhance the thermal and mechanical properties of additively manufactured molds. A series of simple test specimens were produced using mSLA. Sedimentation and printability were analyzed by varying the aluminum oxide mixing ratio. The effect of various additives was also investigated. The composite materials were tested for processability, heat flow and mechanical properties. Scanning electron microscopy (SEM) was used to evaluate the particle size, quantity, distribution and homogeneity of the composite material. To demonstrate the application of the new material in additive tooling, a typical set of tool inserts for injection molding was manufactured.