Pulse-Modulated Laser Printing to Suppress Powder Bed Halo
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-power flux laser systems in powder bed fusion additive manufacturing face issues with laser damage to optics and the generation of plasma, which leads to unwanted 'Halo' effects that negatively impact the printing process by pushing powder particles out of the intended area, reducing the quality of the printed components.
Innovation Solution
The use of a shaped laser beam pulse train with adjustable flux levels between 20 kW/cm2 and 10 GW/cm2, combined with inert gas environments and dynamic adjustments to laser parameters, minimizes powder ejection outside the defined region, reducing plasma generation and optical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high flux laser beam is used to quickly melt and fuse powder layer, then productivity is improved, but plasma is generated and pushed away powder particles to form halos
Solution Approach 1:
The patent applies periodic pulsed laser action instead of continuous irradiation. The laser operates in controlled pulses with specific duty cycles, allowing the powder to melt and fuse during pulse periods while preventing plasma accumulation and shockwave formation during inter-pulse periods. This periodic operation enables high productivity while minimizing halo effects.
Solution Approach 2:
The patent dynamically adjusts laser parameters including flux density, pulse duration, and duty cycle based on the printing stage and material properties. By changing these parameters in real-time, the system maintains high printing speed while preventing plasma generation that causes halo effects. The flux is modulated to stay below plasma threshold while achieving sufficient melting.
2Productivity
If higher peak power is used in the optical train, then productivity is improved, but risk of laser damage to optics increases
Solution Approach 1:
The patent uses pulsed laser operation with controlled duty cycles to deliver high peak power during brief intervals for rapid melting, followed by cooling periods that allow optics to dissipate heat. This periodic action enables high productivity through high peak power while preventing thermal damage to optical components during the inter-pulse cooling periods.
Solution Approach 2:
The patent implements pre-cooling periods and duty cycle management that allow optics to recover from thermal stress before the next high-power pulse. This beforehand cushioning through controlled thermal cycles prevents cumulative thermal damage while maintaining high peak power capability for rapid printing.
3Reliability
If conventional laser power flux is used, then optics damage is reduced, but halo effect still occurs due to plasma generation
Solution Approach 1:
The patent optimizes laser flux parameters to operate in a specific window: high enough to achieve rapid melting and fusion for productivity, but controlled through pulse modulation to stay below the plasma generation threshold. This parameter optimization eliminates halo effects while maintaining optics safety and printing speed.
Solution Approach 2:
By using pulsed operation with appropriate duty cycles, the patent delivers sufficient energy for melting during pulse periods while allowing plasma to dissipate during inter-pulse periods. This prevents the sustained plasma formation that causes halo effects, even at flux levels that would otherwise be dangerous for optics.
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 effectively reduces powder ejection outside the intended area, minimizing 'Halo' effects and enhancing the quality of the printing process by controlling plasma generation and optical damage, allowing for more precise and efficient additive manufacturing.
Implementation Method 1
A shaped laser beam pulse train including one or more pulses and having a flux greater than 20 kW/cm2 is directed at a defined two dimensional region or 'tile' of the powder bed. This energy is sufficient for melting and fusing powder within the defined two dimensional region.
Implementation Method 2
This energy is sufficient for melting and fusing powder within the defined two dimensional region
Implementation Method 3
both damage to optics and unwanted plasma generation can be reduced or mitigated by suitable pulse shaping and timing of high flux lasers
Data Source
AI summary
A method of additive manufacture is disclosed. The method may include providing a powder bed and directing a shaped laser beam pulse train consisting of one or more pulses and having a flux greater than 20 kW/cm2 at a defined two dimensional region of the powder bed. This minimizes adverse laser plasma effects during the process of melting and fusing powder within the defined two dimensional region.