Support optimisation for additive manufacturing

Abstract

The use of 3D printing/additive manufacturing technology has grown rapidly in recent years, with applications in areas like aerospace, automotive and medicine, as well as more traditional prototyping applications. One of the reasons for this rapid growth is the ease with which complex objects can be fabricated when compared to traditional subtractive methods. As the desired objects become ever more complex, it is inevitable that there are overhangs, holes or edges within the structure that require additional support material to prevent collapse and to reduce warping of the part, dependent upon the additive manufacturing method used. This support material has subsequently to be removed, adding additional build time and cost to production of the part. By optimising the support structure and associated manufacturing parameters, it is therefore possible to significantly reduce the time and cost of parts fabricated by 3D printing. This thesis looks at how the support structures can be optimised via process planning, with a particular focus on the printable threshold overhang angle (PTOA) of the support structure and printable bridge length (PBL) to minimise resource utilisation in the printing process. The process parameters’ effects on PTOA and PBL are investigated. A new support generation method is proposed for reducing support waste based on PTOA and PBL. This thesis also looks at how the support materials can be reduced when fabricating multiple components simultaneously, as some parts of a component can act as support structures for another component in multi-part production processes. In some cases, contrarily, increasing support structures can improve the overall efficiency if the support structures have some special functions. Lastly, a support interface method is proposed for easy part removal for direct metal deposition processes.