FDM Process Using Low-Melting Amorphous Polymers
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Solution Overview
Problem
Additive manufacturing methods, such as Fused Deposition Modeling, face challenges in achieving homogeneous material properties due to temperature gradients and irregular crystallization kinetics in semicrystalline thermoplastic polymers, leading to brittle components and warping issues.
Innovation Solution
A method involving the application of a fusible polymer with a controlled melting range of ≥20° C. to ≤100° C. and complex viscosity of ≥10 Pas to ≤1,000,000 Pas, applied within a chamber at a temperature ≤50° C., to build articles layer by layer, reducing temperature gradients and promoting uniform material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional FDM methods use semicrystalline thermoplastic polymers (e.g., PA12) with high melting points, then the material provides high strength and toughness in injection molding, but during additive manufacturing the irregular crystallization kinetics and temperature gradients cause brittle components and warping
Solution Approach 1:
The patent changes the fundamental material parameter by selecting amorphous thermoplastic polymers instead of semicrystalline polymers. Amorphous polymers lack the crystallization kinetics problems that cause warping and brittleness in FDM printing, while still providing adequate mechanical properties. This parameter change resolves the contradiction between material strength and manufacturing precision.
Solution Approach 2:
The patent exploits the phase transition behavior of amorphous polymers, which undergo a glass transition rather than crystallization. This phase transition occurs more uniformly and predictably during cooling, avoiding the irregular crystallization structures that lead to component warping and brittleness in conventional FDM printing of semicrystalline materials.
2Ease of manufacture
If the chamber temperature is maintained high to keep polymer melt fluid during deposition, then layer bonding is improved, but temperature gradients increase causing warping and irregular crystallization
Solution Approach 1:
The patent changes the material's thermal properties by using amorphous polymers with lower glass transition temperatures. This allows the chamber temperature to be maintained lower, reducing temperature gradients while still achieving adequate layer bonding through the polymer's viscoelastic behavior above its glass transition temperature.
3Manufacturing precision
If polymers with low melting ranges are used to reduce warping, then temperature control is improved, but the material may exhibit increased tackiness and reduced processing safety
Solution Approach 1:
The patent changes the material selection to amorphous thermoplastic polymers that inherently provide a more favorable balance between glass transition temperature and processing temperature. This parameter change allows for reduced warping while maintaining adequate processing safety and reduced tackiness compared to semicrystalline polymers with similarly low melting points.
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 reduces component warping, suppresses blister formation, and allows for the use of polymers with low melting ranges, resulting in articles with improved mechanical properties and reduced tackiness, enhancing processing safety and efficiency.
Implementation Method 1
The fusible polymer has a melting range (DSC, differential scanning calorimetry, 2nd heating operation at heating rate 5 K/min.) of ≥20° C. to ≤100° C.
Implementation Method 2
During the melting operation and especially in the course of cooling, an irregular inner structure of the so-called semicrystalline polymers arises (for example PA12 and also PP).
Data Source
AI summary
A process for manufacturing an article comprises the steps of: I) applying a filament of an at least partially fused construction material to a support so as to obtain a layer of the construction material which corresponds to a first selected cross-section of the article; II) applying a filament of the at least partially fused construction material to a previously applied layer of the construction material so as to obtain a further layer of the construction material which corresponds to a further selected cross-section of the article and which is bonded to the previously applied layer; and III) repeating step II) until the article is formed. At least steps II) and III) are carried out in a chamber and the construction material comprises a fusible polymer. The fusible polymer has a fusion range (DSC, differential scanning calorimetry; 2nd heating at a heating rate of 5 K/min.) of ≥20° C. to ≤100° C. The fusible polymer further has a complex viscosity |η*| (determined by viscosity measurement in the melt using a plate-plate oscillating viscometer according to ISO 6721-10 at 100° C. and a shear rate of l/s) of ≥10 Pas to ≤1000000 Pas. Finally, the temperature inside the chamber is ≤50° C. The invention also relates to an article manufactured by the process according to the invention, to an article having a substrate and to an article bonded to the substrate, the article being in the form of an adhesive joint or varnish region, and to the use of a particular polyurethane in fused deposition modeling-based additive manufacturing processes.