Laser Incidence Angle Control for AM Overhang Fusion
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Solution Overview
Problem
Existing additive manufacturing methods using powder-based build materials face challenges in achieving complete fusion at overhang structures, leading to imperfections such as rough surface finishes and structural weaknesses due to incomplete energy beam coverage.
Innovation Solution
The method involves using a secondary energy beam to irradiate points on the edge of the powder bed, forming a distinct angle relative to the primary energy beam, ensuring improved fusion and surface finish at overhang points by controlling the angle of incidence within specific tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single primary energy beam is used to irradiate the powder bed, then the manufacturing process is simple and fast, but complete fusion is not achieved at overhang structures leading to rough surface finishes and structural weaknesses
Solution Approach 1:
The energy beam system is segmented into a primary energy beam for general irradiation and a secondary energy beam specifically targeted at overhang structures. This segmentation allows each beam to perform its specialized function - the primary beam handles bulk material fusion while the secondary beam ensures complete fusion at difficult-to-reach overhang areas, thereby resolving the contradiction between manufacturing precision and device complexity
Solution Approach 2:
The patent applies local quality by directing the secondary energy beam specifically at overhang structures where fusion completeness is problematic. The secondary beam is positioned to irradiate only the edge regions and overhang areas at angles between 45-90 degrees relative to the build plate normal, providing enhanced local fusion quality without affecting the entire powder bed, thus improving manufacturing precision without proportionally increasing device complexity
2Manufacturing precision
If the energy beam irradiates points on the edge of the powder bed at normal angles, then the device operation is simple, but incomplete fusion occurs at overhang points
Solution Approach 1:
The patent implements dynamics by making the secondary energy beam's angle of incidence adjustable and variable. The secondary beam is positioned to irradiate overhang structures at angles between 45-90 degrees relative to the build plate normal, with the optimal angle dynamically selected based on the specific overhang geometry and build requirements. This dynamic angle control enables complete fusion at overhang points while maintaining operational flexibility
Solution Approach 2:
The patent applies parameter changes by modifying the angle of incidence parameter of the secondary energy beam. Instead of using a fixed normal angle like the primary beam, the secondary beam's angle is changed to range between 45-90 degrees relative to the build plate normal, with the specific angle selected based on the overhang structure characteristics. This parameter change enables the beam to effectively irradiate edge points and achieve complete fusion, resolving the contradiction between manufacturing precision and ease of operation
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 results in a 60% improvement in surface finish for down-skin surfaces and a 25% improvement in up-skin surface finish, enhancing the structural integrity and durability of objects with overhanging features.
Implementation Method 1
a laser beam, to melt or sinter a powdered material, creating a solid three-dimensional object
Implementation Method 2
Selective laser melting, and direct laser melting are common industry terms used to refer to producing three-dimensional (3D) objects by using a laser beam to sinter or melt a fine powder
Implementation Method 3
The physical processes associated with laser sintering or laser melting include heat transfer to a powder material and then either sintering or melting the powder material
Implementation Method 4
The energy beam 136 sinters or melts a cross sectional layer of the object being built
Data Source
AI summary
The present disclosure generally relates to methods of additive manufacturing with control of the energy beam incidence angle that allows for aligning the laser beam angle to directly oppose the building direction of an angled wall. The method includes building an object in an additive manufacturing powder bed where the object includes a surface that is defined by a build vector projecting outward relative to the build plate center at an angle Φ relative to normal of the build plate such that 90°>Φ>0° and the directed energy beam forms an angle θL2 relative to normal of the build plate such that 270°>θL2>180°, wherein θL2−Φ=180°±Δ, and Δ<45°. The present methods provide finished objects having overhanging regions with more consistent surface finish and resistance to mechanical strain or stress.