Additive/Subtractive Rapid Pattern Manufacturing for Casting Patterns and Injection Mold Tooling

This paper presents a Rapid Pattern Manufacturing system that involves both additive and subtractive techniques whereby slabs are sequentially bonded and milled using layered toolpaths. Patterns are grown in a bottom-up fashion, both eliminating the need for multi-axis operations and allowing small features in deep cavities. Similar approaches exist in the literature; however, this system is able to provide a larger range of both materials and sizes, from smaller conventional injection mold tooling to very large wood or urethane sand casting patterns. This method introduces a novel sacrificial support structure approach by integrating a flask into the pattern build process. The system has been implemented in an automated machine capable of producing patterns in excess of several thousand pounds in a build envelope over 1m3. In this current research, a new layer bonding method using friction stir welding of aluminum plates is presented. In this manner, one can create seam-free laminated aluminum injection mold tooling using a unique combination of industrial adhesives and friction stir spot welding to secure the slab initially, then continuous friction stir welding of layer perimeters that are subsequently machined in a layer-wise process.