Design and fabrication of a low-volume, high-temperature injection mould leveraging a 'rapid tooling' approach

The costs for low-volume production moulds (1-200 production components) are related to the mould material, the process planning time and the fabrication costs. Researchers have explored using additive manufacturing (AM) processes to fabricate moulds directly from their digital models as this reduces the process planning time and some fabrication costs, but there are issues with directly employing an AM solution. Material costs are high for metallic AM processes, and there are thermal conductivity and material compatibility issues when using plastic-based AM processes. Both the metal- and plastic-based AM processes have surface finish issues; so post processing activities must be part of the fabrication plan. In this research, a methodology is found to fabricate low-volume production moulds using a high-temperature moulding material. A general solution is provided, with a case study focusing on an over moulding process in which the injection material being moulded is Technomelt-PA 7846 black. A hybrid mould fabrication is applied where a material extrusion-based process is used to make a sacrificial product-shaped pattern. This pattern is used to form a resin-based insert which is to be assembled into a mould base frame. Customised inserts can be readily built and exchanged to provide a rapid response to a customer request. An assessment of the digital model, the manufacturing, assembly and the final validated assembly model is provided.