Core-Shell FDM Prints With Porous Core and Smooth Surface
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Solution Overview
Problem
Existing 3D printing methods using FDM technology face challenges in producing lightweight, structurally sound objects with smooth surfaces due to the limitations of thermally unstable photo-curable materials and low thermal conductivity, particularly in applications like LED luminaires and lighting solutions.
Innovation Solution
A core-shell layering method in FDM printing is employed, where a porous core and a non-porous shell are used, with controlled concentrations of pore-forming materials, allowing for simultaneous 3D printing and pore formation, resulting in lightweight objects with maintained structural integrity and smooth surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photo-curable materials are used in polyjet technique to produce smooth surfaces, then surface quality is improved, but thermal stability and thermal conductivity deteriorate
Solution Approach 1:
The patent uses composite materials by combining thermoplastic matrix with pore-forming additives (such as salt particles, sugar, or starch) to create a material that can be printed with FDM technology. The thermoplastic provides thermal stability and conductivity, while the pore-forming additives enable controlled porosity formation after printing, resolving the contradiction between surface quality and thermal properties.
Solution Approach 2:
The patent introduces porous structures into FDM-printed objects by incorporating pore-forming materials that are removed after printing. This creates controlled porosity that reduces weight and can improve thermal management, while the remaining thermoplastic matrix maintains structural integrity and thermal stability, addressing the thermal conductivity issue of photo-curable materials.
2Weight of moving object
If porous structures are introduced to reduce weight, then weight is reduced, but structural integrity may deteriorate
Solution Approach 1:
The patent applies local quality by creating porous structures only in specific regions of the printed object where weight reduction is desired, while maintaining dense solid structures in load-bearing areas. The shell encloses the porous core, providing structural support where needed while allowing porosity in non-critical regions, thus reducing weight without compromising overall structural integrity.
Solution Approach 2:
The patent uses a core-shell structure where a porous core is enclosed by a solid shell. The shell provides structural integrity and strength, while the porous core reduces weight. This nested configuration allows the object to achieve weight reduction through porosity while the outer shell maintains the necessary mechanical strength and structural stability.
3Quantity of substance
If core-shell structure with porous core is used to reduce density, then density is reduced, but surface smoothness may deteriorate
Solution Approach 1:
The patent employs a core-shell structure where the solid shell completely encloses the porous core. This configuration allows the interior to be porous for weight reduction while the outer shell provides a smooth, solid surface finish. The shell acts as a protective layer that hides the porous structure from view and provides the necessary surface quality for applications requiring smooth surfaces.
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 enables the production of lightweight 3D printed items with reduced material usage and enhanced mechanical properties, achieving density reductions of over 10-30% while maintaining smooth surfaces and structural integrity.
Implementation Method 1
heating one or more of (i) the printable material and (ii) the 3D printed material for inducing pore formation
Data Source
AI summary
The invention provides a method for producing a 3D item by means of fused deposition modelling, the method comprising: (a) a 3D printing stage comprising: layer-wise depositing 3D printable material, wherein the 3D printable material comprises 3D printable core material and 3D printable shell material, to provide the 3D item comprising a core-shell layer of 3D printed material, wherein the 3D printed material comprises a core comprising 3D printed core material and a shell comprising 3D printed shell material, wherein the shell at least partly encloses the core, wherein the 3D printable core material comprises a pore forming material with a first concentration c1, wherein the 3D printable shell material comprises the pore forming material with a second concentration c2, wherein c2/c1≤0.9; and (b) a pore forming stage comprising: heating one or more of (i) the printable material and (ii) the 3D printed material.