Multimodal Powder Bed for Selective Laser Melting
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Solution Overview
Problem
Selective laser melting and sintering processes face issues with contamination, porosity, and mechanical weakness due to oxygen and gas occlusion, leading to reduced ductility and premature rupture of parts, as well as manufacturing defects from material ejections during the powder bed fusion process.
Innovation Solution
Employing a powder with a multimodal particle size distribution, specifically bimodal or trimodal, to increase the coordination number and compactness of the powder bed, reducing interstitial spaces and gas trapping, and optimizing the powder preheating and handling to minimize contamination and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If selective laser melting or sintering is used to manufacture parts, then rapid manufacturing capability is achieved, but contamination, porosity and mechanical weakness occur due to oxygen and gas occlusion
Solution Approach 1:
The patent employs an inert atmosphere (argon or nitrogen) throughout the entire manufacturing process to replace oxygen-containing environments. The enclosure is filled with inert gas before powder deposition, and the inert gas flow is maintained during all operations including powder spreading, laser processing, and part construction. This prevents oxidation of powder particles and occlusion of oxygen gases during melting or sintering, thereby eliminating the source of porosity and mechanical weakness while maintaining rapid manufacturing capability.
2Device complexity
If conventional monomodal powder is used, then simple material supply is maintained, but high porosity and gas trapping occur due to low coordination number in powder bed
Solution Approach 1:
The patent uses a composite powder composition consisting of spherical metal particles with a core-shell structure or mixed-size distribution. The composite powder comprises particles of different sizes (e.g., fine particles filling voids between coarse particles) or different material compositions (e.g., metal core with ceramic shell). This increases the coordination number and compactness of the powder bed, reducing interstitial spaces where gases could be trapped during processing, while still allowing for straightforward material supply as a pre-mixed powder blend.
3Productivity
If high scanning speed is used to increase productivity, then manufacturing time is reduced, but material ejections and manufacturing defects increase
Solution Approach 1:
The patent optimizes multiple process parameters simultaneously to enable high scanning speeds without defects. Key parameter changes include: using spherical powder particles with controlled size distribution (45-105 μm) to improve flow and packing; maintaining inert gas flow rates of 5-20 L/min to suppress vaporization and ejections; controlling laser power density and scanning speed ratios to stay within optimal processing windows; and preheating the enclosure to 50-150°C to reduce thermal gradients. These coordinated parameter changes allow high productivity while maintaining surface 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 significantly reduces porosity and manufacturing defects, enhances mechanical properties, and improves the dimensional and metallurgical quality of the parts produced, while also increasing productivity by minimizing material shrinkage and allowing faster scanning speeds.
Implementation Method 1
At least one region of said first layer is scanned with this beam so as to locally heat the powder of this region to a temperature higher than the sintering temperature of this powder
Implementation Method 2
By 'selective laser fusion', in English Selective Laser Melting (SLM), we mean a process whose main characteristics are recalled below
Implementation Method 3
The invention also aims at the rapid manufacture of parts without melting, namely by selective sintering of powder beds by laser
Implementation Method 4
the powder particles thus sintered or melted then form at least a first element in one piece
Implementation Method 5
the powder particles melted or sintered in step (c) and step (e) form a single unit
Implementation Method 6
A second layer of powder of said material is deposited on this first layer of powder
Data Source
Figure 1~2
Figure 3~4B
Figure 5A~5C
AI summary
The invention concerns a method for manufacturing a part by the selective melting or selective sintering of powder beds using a high energy beam, comprising the following steps: (a) providing a material in the form of powder particles (60), (b) depositing a first layer (10) of powder on a support member (80), (c) scanning at least one region of said first layer (10) with the beam (95) in order to heat the powder locally in said region to a temperature higher than the sintering temperature of said powder, such that the particles of said melted or sintered powder from said region form at least one single-piece component (15), (d) depositing a second layer (20) of powder on said first layer (10), (e) scanning at least one region of said second layer (20) with the beam (95) in order to heat the powder in said region to a temperature higher than the sintering temperature of said powder, such that the particles of said melted or sintered powder form at least a second single-piece component (25), (f) repeating steps (d) and (e) for each new powder layer to be deposited above a preceding layer until the part is completely formed. Typically, the powder has a multimodal particle size distribution.