Core-Shell Filament for 3D Printing Distortion Control
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Solution Overview
Problem
Extrusion-based additive manufacturing systems face challenges with semi-crystalline polymeric materials, which exhibit distortions, internal stresses, and sagging due to discontinuous volume changes upon solidification, leading to curling and distortion in 3D models.
Innovation Solution
The use of consumable materials with core-shell arrangements, where the core and shell materials have different crystallization temperatures, allowing the shell material to crystallize upon deposition and the core material to crystallize later, reducing distortions and internal stresses by controlling the crystallization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If semi-crystalline polymeric materials are used for extrusion-based additive manufacturing, then the material provides structural integrity and strength, but the material exhibits distortions, internal stresses, and sagging due to discontinuous volume changes upon solidification
Solution Approach 1:
The consumable material is divided into core and shell portions with different crystallization temperatures. The shell portion crystallizes first upon deposition, providing immediate structural support, while the core portion crystallizes later. This segmentation resolves the contradiction by separating the functions of immediate structural integrity (shell) and final material strength (core), eliminating distortions and sagging caused by simultaneous crystallization.
Solution Approach 2:
The invention changes the crystallization temperature parameter of the consumable material by using different materials for the core and shell portions. The shell material has a higher crystallization temperature than the core material, allowing controlled sequential crystallization. This parameter change enables the shell to solidify first and support subsequent layers, preventing the sagging and distortion that occur when the entire material crystallizes simultaneously.
2Speed
If the consumable material crystallizes quickly upon deposition, then the material solidifies rapidly providing immediate support, but the material develops internal stresses and distortions due to discontinuous volume changes
Solution Approach 1:
The consumable material is segmented into core and shell portions that crystallize at different rates. The shell portion crystallizes quickly upon deposition, providing immediate structural support, while the core portion crystallizes more slowly. This segmentation allows rapid solidification without the harmful effects of simultaneous crystallization throughout the entire material, reducing internal stresses and distortions.
Solution Approach 2:
Different regions of the consumable material have different crystallization characteristics. The shell portion is designed with higher crystallization temperature for rapid solidification and immediate support, while the core portion has lower crystallization temperature for slower, more controlled solidification. This local quality differentiation resolves the contradiction between fast solidification and dimensional accuracy.
3Shape
If support structures are added to prevent sagging during fabrication, then the overhanging portions are supported, but the device complexity and manufacturing time increase
Solution Approach 1:
The consumable material itself provides the support function through its core-shell structure. The shell portion crystallizes first and forms a rigid outer layer that supports subsequent layers and overhanging portions. This self-service approach eliminates the need for separate support structures, reducing device complexity and manufacturing time while maintaining the ability to fabricate complex geometries with overhangs.
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 results in 3D models with reduced curling and distortion, maintaining dimensional accuracy and achieving good interlayer z-bond strengths by allowing the shell material to support subsequent layers while the core material crystallizes slowly.
Implementation Method 1
the shell material to crystallize upon deposition and the core material to crystallize later, reducing distortions and internal stresses by controlling the crystallization process
Implementation Method 2
extrusion-based additive manufacturing system is used to build a 3D model by extruding a flowable modeling material. The modeling material is extruded through an extrusion tip carried by an extrusion head
Implementation Method 3
The extruded modeling material fuses to previously deposited modeling material, and solidifies upon a drop in temperature
Data Source
AI summary
A consumable filament for use in an extrusion-based additive manufacturing system, where the consumable filament comprises a core portion of a first thermoplastic material, and a shell portion of a second thermoplastic material that is compositionally different from the first thermoplastic material, where the consumable filament is configured to be melted and extruded to form roads of a plurality of solidified layers of a three-dimensional object, and where the roads at least partially retain cross-sectional profiles corresponding to the core portion and the shell portion of the consumable filament.