Rapid tooling: A model and methodology for the development of additive manufacturing based tooling for injection moulding

There is a growing demand for low volume manufacturing, short series production and mass customisation in the plastics products industry. Additive manufacturing has frequently been touted as a solution to each of these highlighted demands, but it is yet to make a notable breakthrough into this industry. There are limitations with additive manufacturing in its processes, technologies and the portfolio of materials available, which restrict its use in the plastics industry. There are however compelling economic and time based advantages which can still be extracted from additive manufacturing and applied to modern consumer strategies. The purpose of this research is to investigate how additive manufacturing can be integrated into injection moulding, which is the traditional means of manufacturing plastic products. This is known as rapid tooling. This process is to be complimented with a suite of design recommendations as well as a methodology for choosing which manufacturing method is best suited to any given plastic product design. This thesis focuses on how a tooling system was designed and manufactured which would allow for rapid tooling to be integrated into existing automated injection moulding machinery and which could accommodate tooling for multiple product designs. Using a series of case study products, the effectiveness of rapid tooling was determined by examining the cost, time to manufacture, and the overall quality of the final product. The efficacy of the design recommendations were evaluated and the limitations of rapid tooling were also determined from these case studies. Rapid tooling was found to be an effective tool in both validating tooling design as well as being a cost effective means of iterative design in plastic products. There are still further process improvements to be made however before rapid tooling can be used to manufacture saleable product. A thorough design process as well as a metal based support structure are critical for the success of rapid tooling. This thesis demonstrates that additive manufacturing is not being used as effectively as it could be to solve current market demands and that using it to create rapid tooling can go a long way towards manufacturing functional and safe plastic products. It also goes some way towards solving issues surrounding short volume demand and requirements for custom products. In certain scenarios, it still remains best practice to consider what criteria for success may be when choosing a manufacturing method for a plastic product. This thesis provides some insight as to a direction rapid tooling could bring the community, but it also demonstrates that further research is required surrounding the process parameters of injection moulding when using rapid tooling to make this a more accurate and repeatable process.