Oriented Polymer Powders for Selective Laser Sintering
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Solution Overview
Problem
Existing Selective Laser Sintering (SLS) materials lack an orientation step, resulting in limited process temperature windows and high water absorption, which affects the quality and throughput of produced parts, particularly with polymers like Nylon 6, 11, and 12.
Innovation Solution
Incorporating an orientation step before size reduction, utilizing methods such as high shear two roll milling to produce highly oriented polymer films and powders, which increases melting temperature and heat of fusion, allowing for a wider process temperature window and reduced water absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an orientation step is added before size reduction, then the process temperature window increases and water absorption decreases, but the manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by implementing an orientation step before size reduction in the material production process. This preliminary orientation of polymer chains before granulation creates materials with improved crystallinity and structural order, which subsequently provides a wider SLS processing temperature window and reduced water absorption without requiring changes to the actual SLS process equipment
Solution Approach 2:
The patent changes material parameters through the orientation process, specifically altering the molecular arrangement and crystallinity of the polymer powder. By modifying the internal structure parameters of the material (chain orientation, crystallinity) through mechanical or thermal treatment before size reduction, the material achieves improved thermal stability and reduced hygroscopicity, allowing broader processing temperature ranges
2Reliability
If an orientation step is added before size reduction, then water absorption decreases and part quality improves, but the production time increases
Solution Approach 1:
The orientation step is performed as a preliminary action during material production rather than during each part build process. By pre-orienting the polymer chains and establishing improved crystalline structure in the raw material itself, the benefits carry through to all subsequent production runs, avoiding repeated time-consuming treatments during actual part manufacturing
Solution Approach 2:
The patent replaces potential time-consuming post-processing mechanical treatments with a pre-processing orientation approach. Instead of applying mechanical treatments to finished or semi-finished parts, the orientation is applied to the raw material in bulk form, significantly reducing the time required per part while achieving the same quality improvements
3Temperature
If high shear two roll milling is used for orientation, then molecular orientation increases and melting temperature increases, but the energy consumption increases
Solution Approach 1:
The high shear two roll milling process utilizes phase transitions by heating the polymer material to its melting point or near-melting temperature, transitioning it from solid to molten state, then rapidly cooling it between the rolls to create oriented crystalline structures. This controlled phase transition enables molecular alignment and increases the melting temperature of the resulting material
Solution Approach 2:
The process changes multiple parameters simultaneously: temperature (heating to melt), shear rate (high shear between rolls), and cooling rate (rapid solidification). By optimizing these parameters, the process achieves high molecular orientation and increased melting temperature while managing energy consumption through efficient heat transfer and process integration
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 orientation step enhances the mechanical properties of polymers, expanding the SLS process temperature window, improving part quality and throughput by promoting crystallization and reducing water absorption, leading to better performance and reliability in producing functional parts.
Implementation Method 1
The orientation can be done by any of several conventional processes that are known to those skilled in the art of film and fiber production. Orientation promotes crystallization.
Implementation Method 2
One embodiment uses the high shear two roll mill which is novel.
Data Source
AI summary
A method of providing improved powder materials for selective laser sintering (SLS). and related sintering including High Speed Sintering and Selective Inhibition Sintering, processing by orienting a polymer material. The improved materials increase the melting temperature thus increasing the process temperature window, reduce or eliminate amorphous regions thus reducing water absorption, reduce the toughness thus making size reduction easier, and increase heat of fusion. The orientation may be accomplished by deforming the polymer by drawing, rolling, machining, equal channel angular extrusion or similar processes, or by a high shear two roll mill.