Beam Spot Size Control for Thin Overhang Additive Manufacturing
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Solution Overview
Problem
Additive manufacturing techniques face challenges in achieving consistent material characteristics due to varying shapes of three-dimensional articles, leading to issues like porosities and undesired widening of the melt pool, especially when fusing thin overhangs.
Innovation Solution
The method involves varying the Full Width Half Maximum (FWHM) of a high energy beam as a function of the already fused thickness of the three-dimensional article, using focus lenses, astigmatism lenses, vacuum levels, or aperture sizes to counteract the widening of the melt pool and ensure proper fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constant high energy beam spot size is used during additive manufacturing, then the manufacturing process is simple and fast, but the melt pool widens undesirably when fusing thin overhangs, leading to porosities and inclusions
Solution Approach 1:
The patent implements dynamic adjustment of the high energy beam spot size during the additive manufacturing process. The beam spot diameter is varied as a function of the already fused thickness of the three-dimensional article, allowing the system to adapt to different geometries and maintain consistent melt pool dimensions throughout the build process, thereby preventing porosities and inclusions in thin overhang regions
Solution Approach 2:
The patent changes the physical parameter of beam spot size (FWHM) during the manufacturing process. By decreasing the beam spot size for thinner sections and maintaining larger spot sizes for thicker sections, the system optimizes energy distribution and melt pool control dynamically, resolving the contradiction between manufacturing simplicity and precision
2Manufacturing precision
If the high energy beam spot size is decreased to prevent melt pool widening, then porosity is reduced, but the energy density increases excessively for thicker sections, causing defects
Solution Approach 1:
The patent applies local quality by tailoring the beam spot size to the specific geometric requirements of different regions of the three-dimensional article. Thinner sections receive focused, smaller spot sizes to prevent melt pool widening and porosity, while thicker sections receive larger spot sizes to distribute energy appropriately, ensuring optimal fusion without excessive energy density anywhere in the build
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces or eliminates porosities on negative surfaces and allows for the successful building of thinner overhangs without inclusions, improving the overall material characteristics and structural integrity of the final product.
Implementation Method 1
a high energy beam source for delivering an energy to the powder whereby fusion of the powder takes place
Implementation Method 2
the energy beam is a laser beam or an electron beam
Implementation Method 3
using focus lenses, astigmatism lenses, vacuum levels, or aperture sizes to counteract the widening of the melt pool
Data Source
AI summary
Various embodiments of the present invention relate to a method of using of a focus lens in additive manufacturing for forming a three-dimensional article through successive fusion, with a high energy beam, of parts of at least one layer of a powder bed provided on a work table, which parts correspond to successive cross sections of the three dimensional article, said method comprising the step of: using said focus lens for varying a spot size of said high energy beam on said powder bed as a function of an already fused thickness of said three-dimensional article below said powder which is to be fused. The invention is also related to a method for forming a three dimensional article.