Semi-Crystalline Polymer Additive Manufacturing Crystallization Control
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Solution Overview
Problem
Additive manufacturing techniques face challenges in printing three-dimensional parts with semi-crystalline polymers due to uncontrolled crystallization kinetics, leading to residual stresses, distortions, and dimensional instability, particularly in extrusion-based methods where crystallization kinetics are difficult to manage within suitable temperature windows.
Innovation Solution
The method involves blending semi-crystalline polymers with secondary materials to control crystallization kinetics by retarding or accelerating crystallization processes, using differential scanning calorimetry to identify optimal enthalpy ranges and process windows, allowing for the formation of layers with controlled crystallinity and reduced residual stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If semi-crystalline polymers are used as build materials in extrusion-based additive manufacturing, then the mechanical properties and dimensional stability of printed parts are improved, but uncontrolled crystallization kinetics cause residual stresses and distortions
Solution Approach 1:
The patent modifies the crystallization kinetics parameters of semi-crystalline polymers by blending them with secondary materials. This changes the crystallization rate and temperature profile, allowing control over when and how crystallization occurs during printing. By adjusting these parameters, the patent resolves the contradiction between achieving strong mechanical properties through crystallization and maintaining dimensional stability by controlling the timing and rate of crystallization to minimize residual stresses.
Solution Approach 2:
The patent creates composite build materials by blending semi-crystalline polymers with secondary materials. This composite approach allows the semi-crystalline polymer to provide mechanical strength while the secondary material modifies the crystallization behavior. The composite material thus simultaneously delivers both the desired mechanical properties and controlled crystallization kinetics to prevent distortions.
2Manufacturing precision
If secondary materials are added to control crystallization kinetics, then residual stresses and distortions are reduced, but the complexity of material formulation and processing increases
Solution Approach 1:
Rather than developing complex multi-component formulations, the patent focuses on changing key parameters by adding relatively simple secondary materials. This approach achieves control over crystallization kinetics without requiring elaborate material formulations. The simplicity of the secondary materials helps minimize formulation complexity while still achieving the desired control over crystallization behavior.
3Productivity
If rapid crystallization occurs during printing, then layer solidification is faster improving productivity, but uncontrolled crystallization causes curling and distortions
Solution Approach 1:
The patent modifies the crystallization kinetics parameters to achieve an optimal balance between speed and control. By adjusting the crystallization rate through secondary material addition, the patent enables faster solidification for improved productivity while simultaneously controlling the crystallization profile to prevent curling and geometric distortions. This parameter optimization resolves the contradiction between printing speed and shape accuracy.
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 printing of dimensionally stable three-dimensional items with mechanical properties similar to semi-crystalline polymers, while also allowing for annealing to relieve residual stresses and prevent distortions such as curling, thereby improving the quality and accuracy of printed parts.
Implementation Method 1
heating the material from a solid state to a melting point such that the build material is melted
Implementation Method 2
cooling the melted material until solidified to identify a processing window for the additive manufacturing system
Implementation Method 3
using differential scanning calorimetry to identify optimal enthalpy ranges and process windows
Implementation Method 4
allowing for annealing to relieve residual stresses and prevent distortions such as curling
Data Source
AI summary
A method for printing a three-dimensional part with an additive manufacturing system includes providing a consumable feedstock material comprising a semi-crystalline polymer containing one or more secondary materials, wherein the consumable feedstock material has a process window in which crystalline kinetics are either accelerated or retarded. The consumable feedstock material is melted in the additive manufacturing system. At least a portion of the three-dimensional part from the melted consumable feedstock material in a build environment maintained within the process window.