Selective Laser Melting Confinement Sections for Porosity Reduction
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Solution Overview
Problem
Traditional selective laser melting techniques for metal powders, especially those using highly reflective materials like red gold, suffer from porosity and irregularities due to heat accumulation and laser intensity issues, leading to mechanical and aesthetic defects that require additional processing steps, increasing costs.
Innovation Solution
A method involving scanning metal powder beds with a laser to build confinement sections and intermediate sections, where the laser beam's intensity and scanning pattern are adjusted to confine and fully melt metal powder, reducing porosity and enhancing density, allowing for homogeneous and high-density metal objects without additional processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If close processing is performed both spatially and temporally in selective laser melting, then production efficiency is improved, but heat accumulation occurs causing over-melting, irregularities and porosity
Solution Approach 1:
The processing path is segmented into peripheral portion processing and filling portion processing, executed in separate sequential steps rather than simultaneously. This segmentation allows heat to dissipate between steps, preventing heat accumulation and over-melting while maintaining production efficiency
Solution Approach 2:
The peripheral portion is processed in advance before the filling portion. This preliminary action establishes a thermal boundary that protects the edges from excessive heat accumulation during subsequent filling operations, preventing irregularities and porosity at critical surfaces
2Speed
If high intensity laser is used to melt metal powder, then melting speed is improved, but unmelted powder is removed from adjacent areas reducing homogeneity and final quality
Solution Approach 1:
Different laser intensities are applied to different regions: high intensity is used for the peripheral portion where complete melting is critical, while lower intensity is used for the filling portion where powder distribution homogeneity is more important. This local differentiation resolves the contradiction between melting speed and homogeneity
3Ease of manufacture
If conventional selective laser melting is used on highly reflective metal powder, then processing is performed, but porosity and irregularities increase requiring additional processing steps
Solution Approach 1:
The processing is segmented into two distinct steps: peripheral portion processing with optimized parameters for edge quality, and filling portion processing for interior material deposition. This segmentation enables control of porosity at critical surfaces while maintaining ease of manufacture for complex geometries
Solution Approach 2:
The processing alternates between different parameter sets for peripheral and filling portions. This periodic application of different processing conditions allows optimization for both edge quality (low porosity) and manufacturing efficiency without requiring additional post-processing steps
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 method significantly reduces porosity to near 0% and increases the mechanical strength of metal objects, maintaining high density and aesthetic quality, even with highly reflective materials, using standard laser sources and reducing the need for further processing.
Implementation Method 1
scanning a metal powder bed by means of a laser beam configured to complete a plurality of melting paths
Implementation Method 2
the laser is configured to melt the metal powder into successive layers of material
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
A method for performing a selective laser melting of metal powder to manufacture an object (10), comprises the following steps: scanning a metal powder bed by means of a laser beam configured to complete a plurality of melting paths (D) so as to build a plurality of confinement sections (1,3,5,7) each having its own predefined width, said confinement sections (1,3,5,7) delimiting between them a confinement space (C) having a predefined width; scanning a metal powder bed by means of a laser beam configured to complete at least one melting path (P) within the confinement space (C) so as to selectively melt the material present in said confinement space (C) in order to build an intermediate section (2,4,6) having a predefined width.