Laser Beam Profile Switching for Faster Powder Bed Fusion
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Solution Overview
Problem
In laser processing for additive manufacturing, increasing optical power to enhance processing speed leads to material vaporization, resulting in porous regions due to the Gaussian transverse beam distribution, necessitating a reshaped energy intensity profile to avoid ablation thresholds.
Innovation Solution
Generating a laser beam with first and second transverse beam profiles of different energy density distributions, where the first is non-Gaussian and flatter-topped, and the second is Gaussian or Gaussian-like, and dynamically adjusting the beam or working surface to switch between these profiles during scanning, using a beam profile reshaping device and optical adjustment mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical power is increased to enhance processing speed, then productivity is improved, but material vaporization occurs resulting in porous regions
Solution Approach 1:
The patent changes the beam profile parameter from Gaussian to flat-top distribution, which redistributes the energy density across the beam cross-section. This allows higher total optical power to be delivered without concentrating excessive energy at the beam center, thereby preventing material vaporization while maintaining high processing speed and component density.
Solution Approach 2:
The flat-top beam profile creates a uniform energy distribution across the entire beam cross-section, ensuring that no localized region receives excessive energy density. This local quality control prevents vaporization in high-intensity zones while maintaining efficient melting across the entire scan area, resolving the contradiction between speed and density.
2Productivity
If optical power is increased to enhance processing speed, then productivity is improved, but harmful factors increase due to material vaporization
Solution Approach 1:
By changing the beam profile parameter from Gaussian to flat-top distribution, the patent eliminates the high-intensity center region that causes vaporization. This parameter change allows higher optical power to be used without generating harmful vaporization effects, thus improving productivity while preventing porous region formation.
3Manufacturing precision
If beam profile is reshaped to avoid ablation threshold, then manufacturing precision is improved, but device complexity increases due to additional optical components
Solution Approach 1:
The patent achieves beam profile reshaping by changing propagation distance, a natural parameter of laser beam physics. This approach avoids the need for complex deformable mirrors or diffractive optical elements, thereby improving energy intensity profile control while minimizing increases in device complexity.
4Manufacturing precision
If single beam profile is used to avoid vaporization, then manufacturing precision is maintained, but productivity decreases due to conservative power settings
Solution Approach 1:
The patent dynamically switches between flat-top and Gaussian beam profiles based on the processing requirements of different regions. This dynamic adaptation allows the system to use flat-top profiles for high-power melting operations and Gaussian profiles for precision work, thereby maintaining manufacturing precision while maximizing productivity through optimized power settings.
Solution Approach 2:
The patent segments the build area into different regions that require different beam profiles. By dividing the processing space and applying appropriate beam profiles to different segments, the system achieves both high productivity in bulk material processing and high precision in critical areas, resolving the contradiction between speed and quality.
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 allows for higher power laser beams to be used without vaporizing material, enabling faster processing while maintaining component density and surface finish by selectively applying different beam profiles for core and border solidification in powder bed fusion processes.
Implementation Method 1
A laser beam is then scanned across areas of the powder layer that correspond to a cross-section of the object being constructed. The laser beam melts or sinters the powder to form a solidified layer.
Implementation Method 2
Powder bed fusion apparatus, such as selective laser melting (SLM) and selective laser sintering (SLS) apparatus, produce objects through layer-by-layer solidification of a material, such as a metal powder material, using a high-energy beam, such as a laser beam.
Implementation Method 3
a beam profile reshaping device for shaping a beam profile of a laser beam delivered using the beam delivery optic
Implementation Method 4
carrying out a scan of the laser beam across a working surface, wherein, during the scan, the laser beam and/or working surface is adjusted
Data Source
AI summary
A method of laser processing including generating a laser beam having, at different longitudinal positions in a propagation direction, first and second transverse beam profiles of energy density. The first transverse beam profile is different to the second transverse beam profile and is non-Gaussian. The method includes carrying out a scan of the laser beam across a working surface, wherein, during the scan, the laser beam and/or working surface is adjusted such that, for a first part of the scan, the first transverse beam profile is located at the working surface and, for a second part of the scan, the second transverse beam profile is located at the working surface.