Additive manufacturing of down-skin layers

Abstract

A method for radiation based additive manufacturing of a three-dimensional object from powdered material is disclosed, wherein a plurality of layers of the powdered material are provided in a layer providing direction and are irradiated layer by layer, and the plurality of layers comprises an overhang layer with a core region and a down-skin region for forming a core portion and an overhang portion of the manufactured three-dimensional object, respectively, the core region extending in the layer providing direction on top of an irradiated region of a directly preceding layer and the down-skin region extending on top of a previously nonirradiated region of the directly preceding layer. The method comprises generating the directly preceding layer of the overhang layer, and generating the overhang layer by providing a core energy density into the core region at least up to a preset distance from a transition to the down-skin region, and providing a slope depending overhang energy density into down-skin micro-regions of the down-skin region, wherein the slope depending overhang energy density differs from the core energy density by a down-skin reduction that depends on an extent of the respective down-skin micro-region beyond the respective core region of the directly preceding layer.

Description

technical field [0001] The present application relates generally to additive manufacturing and more particularly to controlled additive manufacturing of lower skin layers. Background technique [0002] In additive manufacturing such as selective laser sintering or selective laser melting, powder material such as metal or ceramic powder is irradiated with electromagnetic radiation such as a laser. Subsequently, the thin layer of powder is arranged in the cavity on the build platform, so that a three-dimensional object is formed in a layer-by-layer, step-by-step manner, ie in the layer arrangement direction. An exemplary device for additive manufacturing is disclosed in document EP 2732890A2. [0003] In general terms, the radiation zone can be displaced laterally, so that the layer can form an overhang, for example a sequence of layers, in the layer arrangement direction, referred to herein as an overhang layer. The depending layer includes a core region for forming the cor...

AI Technical Summary

Problems solved by technology

Thus, additive manufacturing of overhanging regions can result in corresponding overhanging portions of three-dimensional objects that may not be able to fulfill desired specifications such as shape accuracy, stability, and overall structure.

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