On December 12, the team of Professor Wang Chengyong, executive director of Guangdong Precision Medicine Application Society, chairman of the Medical-Industrial Integration Branch, and professor of Guangdong University of Technology, published a research entitled "Sound Continuous Production of Thermosets" in Advanced Functional Materials.
As we all know, thermoset-based materials are widely used in many emerging fields due to their excellent mechanical properties, thermal stability and chemical resistance. Until now, the manufacture of thermoset-based materials has relied mainly on autoclaves or high-temperature molding, which have long manufacturing cycles and high costs. 3D printing based on light curing and heat curing has become an important technology for the rapid manufacture of thermosetting base materials, but due to the poor light penetration and low temperature control sensitivity, the existing 3D printing technology is not yet able to manufacture thermoset base material parts with functional gradient characteristics, complex geometries and heterogeneity.
Compared with common light, heat and other energy sources, sound waves have the advantages of non-contact penetration, long-distance and efficient transmission, wide adjustable frequency, high focusing, etc., and are widely used as auxiliary energy to control the arrangement of microparticles or fibers in 3D printing
Based on the mechanical, physical and chemical complex mechanism of sound waves and thermosetting materials, the researchers realized the 3D printing of various forms of thermosetting matrix structural parts, and continuously controlled the shape and performance of the structural parts by using the non-contact penetrable focused sound waves generated by the piezoelectric effectAcoustic energy can be applied directly to any position for continuous printing, or it can be continuously printed in any direction.
Continuous sonic printing
The rapid collapse of the cavitation bubbles causes the formation of local high temperature and high pressure in the focused area of the sound wave, which promotes the breakage of polymer bonds and the generation of free radicals, thereby rapidly promoting the cross-linking and polymerization of thermosetting materials and curing molding.
In addition, the researchers also found that sound waves can effectively promote the bonding of interfaces, form strong interface bonding, avoid the internal defects of parts caused by the step effect between layers of traditional 3D printing technology, and realize the continuous printing of heterogeneous materials with strong interface bonding even in heterogeneous materials.
360° full-dimensional free printing
The researchers integrated the sound head and nozzle on the six-axis robotic arm, and set the motion trajectory of the sound head through numerical control programming, expanding the printing degree of freedom, this technology has the controllability of time and space, can continuously and smoothly print a variety of special shape structural parts, and creates vertical and transverse spiral structures without support, successfully achieving 360° full-dimensional free printing.
Printing across scales 9
The researchers printed filaments with diameters from 200 m to 2 cm only by adjusting the diameter of the sound head, which met the needs of large-span manufacturing, and combined with the template method, the feature size of less than 100 m could be realized, which greatly expanded the design flexibility.
Multi-material printing
The researchers have developed a series of thermosetting materials with different curing systems such as PDMS-based, acrylate-based, epoxy-based and other thermosetting materials with strong physical effects under the action of sound waves, which can cause polymerization reactions and complete solidification conversion, also known as sound-sensitive materials, including PDMS-based, acrylate-based, epoxy-based and other thermosetting materials with different curing systems, which initially shows that the technology has a wide range of material adaptability.
In addition, the researchers used this technology to directly print structural parts composed of different thermosetting materials (epoxy resin, acrylate, acrylate + epoxy resin + iron), realizing the one-time molding of structural parts with multiple functional properties without assembly, bringing a broader design space for multi-material 3D printing.
Performance-controllable printing
The technology also has a wide range of performance control capabilities, changing the intensity of sound waves can adjust the curing degree of materials, realize the regulation from liquid-colloidal-solid, so as to regulate the mechanical properties, realize the manufacturing of functional gradient materials, and can be extended to the printing of special materials such as metamaterials, organ models and biomimetic composite materials.
Rotation printing
Some functional thin-walled cylinders, which are difficult or inefficient to manufacture by traditional molding and printing methods due to their thin walls, can be easily achieved by introducing a rotating axis into the technology.
The researchers used this technology to directly print functional composite materials, and used the strong penetration of sound waves to achieve air barrier printing. It can be directly printed by adding reinforcing materials such as particles, fibers, etc., such as magnetic scaffolds for cardiovascular**, porous ceramic composites, and ceramic-metal composite continuums.
In conclusion, sonic continuous controllable 3D printing is a new strategy for rapid printing of thermoset-based material parts, which has the characteristics of cross-scale, multi-material, full degrees of freedom, performance control, penetration, green and low energy consumption compared with other printing technologies. In the future, this technology can also be combined with other printing methods, such as DLP technology, which is expected to enable micro- and nano-scale printing of parts made of thermoset-based materials. Break through the current manufacturing capabilities of 3D printing.
This research work has been supported by the National Natural Science Original Exploration Program project "Acoustic Manufacturing Principles and Shape Control Methods of High-performance Parts" (No.).52250109).
References: Article**: 3D Printing Technology Reference.