Structured approach towards surface feature classification on DED-printed parts

Highlights • Nomenclatures and classifications for systematic unequivocal labelling of surface features and defects for component specification and defect assessment are provided. • The key to comprehensive structured quantitative assessment of geometric features and defects of components made using directed energy deposition is application of a low-pass geometry filter to scanned data of such components. • Filtering of 3D geometry data on DED component enables quantitative assessment of large scale deviations as well as local features by means of computation of the local spatial distance to the filtered geometry. • The effective wall thickness computed from the filtered data provides a moving average for local assessment as well as statistical information of the thickness distribution of the component or a relevant section of it. Directed Energy Deposition is a proven technology for the economic production of medium to large sized metal structures. The process results in a characteristic surface structure composed of the molten layers. It is evident that, the surface structure impairs the strength of the workpiece during static and cyclic loading. Consequently, surface topology evaluation is crucial in the assessment of workpieces manufactured by Directed Energy Deposition. In this paper, methods for assessment and specification of workpieces are presented. First, a structured feature table is proposed, which allows the unambiguous and technical specification of surface features. Second, a workflow using a geometry filter on scanned final product data for the assessment of macro workpiece deviations and local features is presented and applied on exemplary workpieces. The exemplary results are critically reviewed in context to industrial application.