Pulse-Modulated Laser Printing to Limit Plasma Halo in Powder Beds
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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 unacceptable 'Halo' effects and reduced printing quality due to powder ejection beyond the defined region.
Innovation Solution
A method involving a shaped laser beam pulse train with adjustable flux between 20 kW/cm2 and 10 GW/cm2, combined with dynamic adjustments in pulse width and area, is directed at a two-dimensional powder bed, using a system with pre-amplifiers and power amplifiers, and an inert gas atmosphere to minimize plasma generation and powder ejection.
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 unacceptable halos
Solution Approach 1:
The patent applies periodic pulsed laser action instead of continuous beam. The laser delivers energy in controlled pulses with specific duty cycles, allowing the powder to melt and fuse during pulse periods while preventing plasma accumulation during off-periods. This periodic operation enables high flux densities (10^6-10^8 W/cm²) without sustained plasma formation that causes halo effects.
Solution Approach 2:
The patent changes key laser parameters including flux density (10^6-10^8 W/cm²), pulse duration, and duty cycle to control the melting process. By adjusting these parameters, the system achieves rapid fusion while keeping peak plasma generation below thresholds that cause harmful shockwaves and powder ejection.
2Productivity
If higher peak power is used in optical train, then productivity is improved, but risk of laser damage to optics increases
Solution Approach 1:
The pulsed laser operation with controlled duty cycles allows high peak power delivery during pulses while providing cooling periods between pulses. This prevents continuous thermal accumulation in optical components, reducing the risk of optics damage while maintaining high productivity during active melting periods.
Solution Approach 2:
The system dynamically adjusts laser flux, pulse duration, and repetition rate based on process requirements. This dynamic control allows optimization of peak power for productivity while managing thermal load on optics through variable duty cycles, preventing damage while achieving rapid melting.
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 laser damage and plasma-induced 'Halo' effects, maintaining high printing quality by controlling powder ejection and ensuring that less than 99% of powder particles remain within the defined region, thereby improving the additive manufacturing process.
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
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.