PAEK Powder Size Distribution Control for Selective Laser Sintering
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Solution Overview
Problem
In selective laser sintering (SLS) processes using polyaryletherketone (PAEK) powders, small particles with diameters less than 30 microns melt prematurely, leading to issues like pilling and structural failures due to inadequate control over particle size distributions, which existing methods attempt to address by excluding or reducing particles below a certain size, but this reduces yield and doesn't fully solve the problem.
Innovation Solution
A method to prepare PAEK feedstock by determining particle size distribution based on the number of particles in each size range, specifically limiting the number of particles with depressed melting temperatures relative to the average melting temperature, rather than relying on mass or volume, to inhibit premature melting during the SLS process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particle size distribution is not controlled, then small particles remain in feedstock causing premature melting and pilling, but controlling it by excluding small particles reduces yield
Solution Approach 1:
The patent changes the parameter basis from mass-based to number-based particle size distribution control. By determining PSD based on the number of particles rather than mass, the process can identify and remove a small number of problematic fine particles (which have depressed melting temperatures) without excluding large numbers of usable particles, thus maintaining high yield while ensuring process reliability
Solution Approach 2:
The patent replaces traditional mass-based classification methods with number-based particle counting and analysis. This substitution allows for more precise identification of problematic particles based on their count distribution across size ranges, enabling targeted removal of only those particles causing premature melting while preserving yield
2Reliability
If particles below 30 microns are excluded from feedstock, then premature melting is reduced, but yield of powder grinding operation decreases
Solution Approach 1:
The patent applies local quality control by identifying and removing only specific particles within certain size ranges that exhibit depressed melting temperatures, rather than applying a blanket exclusion criterion to all particles below 30 microns. This localized approach targets only the problematic particles while preserving usable particles, minimizing material loss
Solution Approach 2:
The patent substitutes mass-based PSD analysis with number-based particle counting to identify problematic fine particles. This allows differentiation between particles that cause issues (fine particles with depressed melting points) and those that are acceptable, enabling selective removal that preserves yield
3Ease of manufacture
If mass-based particle size distribution is used, then conventional control is maintained, but fine particles causing premature melting are not adequately identified
Solution Approach 1:
The patent replaces mass-based PSD measurement with number-based particle counting and distribution analysis. This substitution provides more accurate identification of fine particles that cause premature melting, as number-based methods are more sensitive to the presence of small particles that would be masked in mass-based distributions
Solution Approach 2:
The patent implements feedback through number-based PSD determination that provides more accurate information about the actual count of problematic fine particles. This feedback enables better control decisions by revealing the true distribution of particles by number rather than mass, allowing precise identification of particles requiring removal
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 premature melting by accurately accounting for the number of small particles, enhancing the quality and yield of the SLS process without the economic drawbacks of excluding large numbers of particles, thereby improving the structural integrity and efficiency of the manufacturing process.
Implementation Method 1
Selective laser sintering (SLS) is an additive manufacturing process that uses a high power laser (for example, a carbon dioxide laser) to fuse small particles of plastic, metal (direct metal laser sintering), ceramic, or glass powders into a mass having a desired three-dimensional shape
Implementation Method 2
The laser is controlled to selectively fuse the powdered layer by scanning portions of the cross-section corresponding to a three-dimensional digital description of the part on the surface of a powder bed
Implementation Method 3
Smaller particles, for example having a diameter of less than 30 microns, can melt from 5 to 50 degrees Celsius below the glazing point. This is a disadvantage because such particles begin melting prematurely during the recoating process, for example before and while they are being dispersed on the layer-wise bed prior to laser sintering
Data Source
Figure 1
AI summary
A process for preparing a feedstock having polyaryletherketone particles for using in selective laser sintering. The process includes the steps of determining a particle size distribution of the polyaryletherketone particles in the feedstock based on a number of particles corresponding to each of a plurality of particle size ranges to obtain a particle size distribution determination. The process further includes the step of reducing the number of particles in the feedstock corresponding to one or more size ranges having a depressed melting temperature relative to the average melting temperature of the polyaryletherketone particles in the feedstock based on the particle size distribution determination.