Design and manufacturing methods for fused deposition modelling in additive manufacturing for the South African railway industry.

Abstract

Additive Manufacturing, commonly known as 3D printing, is a transformative technology that has seen rapid adoption in well-established industrial environments due to its increasing reliability and associated economic value. It’s adoption within the South African industry has been driven by the biotechnical/medical, aerospace and automotive industries, with limited adoption in the railway industry. The rolling stock and rail infrastructure consists of numerous systems and components that may benefit from the technology within the railway environment. This study explores utilizing additive manufacturing technology as an additional technique to create functional railway-related components. The study aims to develop tools, methods, and processes for designing and manufacturing functional end-use railway parts, ultimately allowing the industry to derive the economic benefits of additive manufacturing. The study is limited to using the Fused Deposition Modelling technique and polymer materials. Firstly, the available physical and digital manufacturing workflow techniques are identified through literature with recommendations for best practices. Secondly, the research proposes a Multi-Criteria Decision-Making methodology based on the Analytic Hierarchy Process to identify potential railway-related parts that may benefit from the Fused Deposition Modelling additive manufacturing process. The methodology is validated through case studies found in literature. Thirdly, a novel method to optimise the infill design is presented for improving the strength of the 3D printed parts, thereby making the parts more suitable for the railway environment. The method is based on combining Finite Element Analysis and Bi-directional Structural Optimisation Topology Optimisation. Lastly, the study presents a custom-developed application built using Visual Basic and Excel. The application is built upon a generic design process to aid railway design engineers in effectively using the Fused Deposition Modelling technology to create functional 3D printed parts. The research concludes with a case study of a roof scoop and air vent, which was identified, redesigned, optimised, and manufactured using Fused Deposition Modelling. The part was used as a replacement component on a railway inspection vehicle. Compared to the existing design, an 18,7 % reduction in shear stress was achieved for the 3D printed design.