Pulverulent Nylon 5 for MJF 3D Printing Residual Stress Reduction
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Solution Overview
Problem
Current 3D-printing technologies face challenges with residual stresses in powder bed-based systems due to limited operating windows between melting and recrystallization temperatures of polymers, leading to deformation and porosity issues in printed objects.
Innovation Solution
Development of pulverulent nylon 5 with a broader operating window, achieved through precipitation and addition of fillers and flow agents, allowing for effective localized melting and reduced residual stresses during the 3D-printing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polymer with a narrow operating window between melting and recrystallization temperatures is used, then the material can be processed, but residual stresses increase causing deformation and displacement of the printed object
Solution Approach 1:
The patent changes the thermal parameters of the polymer material by selecting nylon 5 and controlling its crystallization behavior. The process modifies the operating window parameters through controlled cooling rates and temperature management, allowing the polymer to maintain low modulus during printing while avoiding premature crystallization that would cause residual stresses and deformation.
2Strength
If the polymer modulus is kept high to maintain structural integrity, then the object maintains shape, but residual stresses increase causing the object to leave the build plane
Solution Approach 1:
The patent applies dynamic control of the polymer's mechanical properties by managing the temperature profile during printing. The nylon 5 material dynamically transitions between solid and molten states, with the modulus adjusting in real-time based on temperature. This allows the material to be soft during deposition for low residual stress, then solidify to provide structural integrity, creating a dynamic balance between strength and stress control.
3Manufacturing precision
If the operating window is expanded to reduce residual stresses, then dimensional accuracy improves, but material selection is limited as few polymers have sufficient window breadth
Solution Approach 1:
The patent expands the operating window of nylon 5 by modifying its thermal parameters through controlled crystallization. By adjusting the cooling rate and temperature profile, the effective operating window is extended, allowing sufficient time for layer deposition before crystallization begins. This parameter control approach makes nylon 5 suitable for MJF printing despite it not being a traditionally wide-window material.
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 use of pulverulent nylon 5 with a wider operating window and controlled particle size distribution reduces residual stresses and thermal degradation, enabling the production of objects with lower porosity and improved mechanical properties in SLS, MJF, and HSS 3D-printing systems.
Implementation Method 1
Multi jet fusion (MJF) 3D-printing employ multiple jets that similarly deposit successive layers of IR absorbing ink onto powder material, followed by exposure to IR energy for selective melting of the powder layer
Implementation Method 2
both the modulus and the volumetric change of the molten phase should be suitably low. This is so the selectively molten areas do not induce large enough residual stresses into the object that it leaves a build plane
Implementation Method 3
An embodiment of the disclosure may provide a precipitated pulverulent nylon 5 formed through precipitating the nylon 5 in a solvent, allowing the polymer to form crystallites
Data Source
Figure 1
AI summary
A nylon 5 powder suitable for three-dimensional printing is provided. The process includes adding nylon 5 and ethanol to a container; wherein an amount of ethanol is about two to five times an amount by weight of the nylon 5; raising a temperature in the container to between about 130 degrees Celsius and about 150 degrees Celsius; forming a solution of nylon 5 in the ethanol; cooling the solution to a precipitation temperature of the nylon 5 to between about 100 degrees Celsius and about 125 degrees Celsius; agitating the solution; precipitating the nylon 5 in powder form from the solution; and removing the nylon 5 powder from the container.