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ORIGINAL ARTICLE

A new method of design for additive manufacturing including machining constraints Vincent Benoist 1,2 & Lionel Arnaud 2 & Maher Baili 2 Received: 3 June 2020 / Accepted: 7 September 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020

Abstract Metal additive manufacturing is a major field of study and innovation. In almost every industry, a lot of effort goes into modelizing and optimizing designs in order to minimize global mass. In this context, despite all efforts, metal additive manufacturing, especially SLM, still produces parts generally considered as raw parts with some surfaces still needing to be machined in order to obtain the required geometrical quality. Despite sometimes, great complexity and cost, the machining stage is never taken into account in the design process, especially during the topological optimization approach. This paper proposes a new design for the additive manufacturing method in order to optimize the design stage and takes into account topological optimization machining as well as geometrical and mechanical constraints. The machining constraints are initially integrated as forces and functional surfaces, but also as the result of a topological optimization loop, in order to find the best possible mounting solution for machining. It is shown on a typical aeronautic part that machining forces may be indeed the greatest forces during the part’s lifetime. Using two different topological optimization software, i.e. Inspire and Abaqus Tosca, the paper illustrates that it is possible to take into account most of the machining constraints to only slightly modify the initial design and thus simplify the machining stage and reduce cost and possible failure during machining. Keywords SLM . DfAM . Topology optimization . Machining . Functional surfaces

1 Introduction Additive manufacturing (AM) processes, such as SLM (selective laser melting) [1–3], are a breakthrough technology for prototyping and even for mass production. The main drawback of metal additive manufacturing is the relatively poor dimensional accuracy [4, 5], about one-tenth of a millimetre which usually constrains the produced part to be machined. So, metal additive manufacturing may not be seen only as a competitor to a machinist but a new opportunity to extend their field of activities. Metal additive manufacturing is currently mainly used in two different ways [6, 7]. Firstly, there is the additive

* Vincent Benoist [email protected] 1

Cousso, Mécapole, Cassou de herre, 32110 Nogaro, France

2

Laboratoire de Génie de Production, École Nationale d’ingénieur de Tarbes, 47 avenue d’Azereix, 65000 Tarbes, France

manufacturing of iso-design parts; this still appears to be the main method used nowadays. The goal here is to reduce the time of the trial and error loop. Secondly there is the full DfAM approach including topology optimization which improves weight, stiffness, assembly or fluid circulation. When using topology optimization software, various design rules must be observed to ensure