Development of a novel benchmark artifact for Additive Manufacturing processes

Additive Manufacturing (AM) allows generation of geometrically complex parts which cannot be obtained by conventional processes (machining, forging, casting e.g.). It also enables production of near net shape parts requiring few finishing operations before use (roughness reduction e.g.). Mastering geometrical and dimensional accuracy of additively manufactured parts is then mandatory to ensure their functionality. In conventional processes, dimensional accuracy of different machines or process conditions (hard machining vs super finishing e.g.) can be objectively compared using the International Tolerance (IT) grades defined by the International Standard Organization (ISO) in ISO 286-1 GPS standard (Geometrical Product Specifications). Required geometrical accuracy can be specified using ISO 1101. In the specific case of blank produced by machining operations, ISO 2768-1 is often used for dimensional tolerancing and ISO 2768-2 for geometrical tolerancing. In the case of Additive Manufacturing, neither dimensional and geometrical tolerancing standard nor benchmarking method standard exist. The solution proposed by many authors is to develop their own benchmark artifact to evaluate the dimensional and geometrical accuracy of their machine, their minimal achievable detail size as well as their capability to replicate a given shape within a given International Tolerance grade. This article aims to make a review of the existing benchmark artifacts and to summarize the main requirements chosen by authors. From this state of the art, a new benchmark artifact is proposed by adapting an existing one to fulfil its missing characteristics. Measurements possibilities in terms of dimensions are enumerated and organized using ISO 286 dimensional intervals as presented in the literature. Geometrical evaluation possibilities are also listed and enumerated. It is then applied to a part obtained by Fused Deposition Modelling (FDM).