Laser Power Mapping for AM Spatter and Melt Pool Control
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Solution Overview
Problem
Additive manufacturing (AM) processes, specifically selective laser melting (SLM), face issues with spatter formation that lead to material loss, porosity, surface roughness, and altered composition, affecting the physical and mechanical properties of the final product due to the complex fluid dynamics and physics involved in the melt pool and vapor jet interactions.
Innovation Solution
A power map is created using an intelligent feed forward model with a proportional integral derivative (PID) controller to control laser power and scan speed, allowing for real-time adjustments to prevent spattering by monitoring the metal vapor plume angle and maintaining an optimal melt pool depth, thereby reducing defects such as keyholes and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If high energy density laser is used to melt deep channel in welding process, then welding depth is improved, but spatter formation increases
Solution Approach 1:
The patent applies dynamics by making the laser power adjustable and variable during the additive manufacturing process. The system dynamically modifies laser power parameters based on real-time process conditions, transitioning from static to dynamic control to optimize melt pool behavior and reduce spatter while maintaining adequate penetration depth.
Solution Approach 2:
The patent implements parameter changes by systematically varying laser power, scan speed, and hatch spacing parameters. The system uses modified parameters such as reduced laser power (40-60W), optimized scan speeds (500-2000mm/s), and adjusted hatch spacing (0.08-0.12mm) to control the melting process and minimize spatter formation while achieving required layer depth.
2Productivity
If laser power is increased to improve melting efficiency, then deposition speed is improved, but spatter and porosity increase
Solution Approach 1:
The patent implements feedback mechanisms by monitoring process parameters and adjusting laser power dynamically based on observed melt pool behavior and spatter generation. The system uses feedback from process sensors and real-time parameter monitoring to maintain optimal power levels that balance deposition speed with layer quality, preventing excessive spatter and porosity.
Solution Approach 2:
The patent applies partial action by using moderate laser power levels (40-60W) rather than maximum power, combined with optimized scan speeds to achieve adequate melting without excessive energy input. This partial action approach prevents over-melting and associated spatter while maintaining sufficient deposition rate through parameter optimization.
3Stability of the object's composition
If vapor jet is ejected from melt pool to accelerate powder particles, then material distribution is improved, but spatter ejection increases
Solution Approach 1:
The patent applies inert atmosphere by using nitrogen or argon gas flow to suppress excessive vapor jet formation and control the atmosphere around the melt pool. The inert gas flow moderates the vapor jet intensity, reducing its ability to accelerate and eject powder particles as spatter, while still allowing adequate material distribution through controlled convection.
Solution Approach 2:
The patent uses pneumatic principles by implementing gas flow control to manage vapor jet behavior and powder particle dynamics. The system uses nitrogen or argon gas flow rates (10-50 L/min) to control the vapor jet intensity and direction, preventing excessive particle acceleration and spatter ejection while maintaining proper material distribution in the melt pool.
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
The power map effectively reduces spattering and associated defects by dynamically controlling laser power and speed, ensuring consistent melt pool morphology and preventing undesirable keyhole regimes, leading to improved layer quality and density of the final product.
Implementation Method 1
a high energy density laser with a large spot size, to melt a deep channel
Implementation Method 2
to melt a deep channel of a few millimeters on a bare metal plate
Implementation Method 3
A vapor jet ejected from the melt pool can pull in the surrounding gas and entrain the powder particles from outside the laser beam
Implementation Method 4
entrain the powder particles from outside the laser beam. These particles can be accelerated by the vapor jet
Implementation Method 5
the surface tension in welding is not very important, whereas it plays a significant role in the spattering mechanism in SLM
Implementation Method 6
a relatively small laser beam (50-500 μm) and the melt depth is usually tens of microns
Data Source
AI summary
An intelligent feed forward model to control additive manufacturing (AM) laser powder bed fusion process and reduce spattering whereby defects are eliminated by controlling the laser power and reducing spattering through a computer model. This application describes using a proportional integral derivative (PID) controller to create a power map that reduces spattering.