Advancements and Challenges in 3D Printing Technology: From Prototyping to Structural Load-Bearing Parts

3D printing, also known as additive manufacturing, is considered a disruptive technology in the manufacturing field because of its unique free-forming capabilities that greatly meet the needs of high-end equipment and components for high integration, multifunctionality, lightweight, and integration. , which has received great attention and initial application in aerospace and other fields. However, compared with traditional manufacturing technologies, 3D printed materials generally have poor fatigue properties under cyclic loading, which seriously restricts their widespread application as structural load-bearing parts.

3D printers appeared in the mid-1950s and are actually rapid prototyping devices that utilize technologies such as light curing and paper lamination. It works on the same principle as an ordinary printer. The printer is filled with “printing materials” such as liquid or powder. After being connected to the computer, the “3d printing materials” are superimposed layer by layer through computer control, and finally the blueprint on the computer is turned into a physical object. This printing technology is called 3D three-dimensional printing technology.

3D printing technology is actually a collective name for a series of rapid prototyping technologies. Its basic principles are stacked manufacturing. The rapid prototyping machine forms the cross-sectional shape of the workpiece through scanning in the X-Y plane, and the layer thickness is intermittently measured at the Z coordinate. The displacement finally forms a three-dimensional part. Rapid prototyping technologies on the market are divided into 3DP technology, FDM fusion lamination molding technology, SLA stereolithography technology, SLS selective laser sintering, DLP laser molding technology and UV ultraviolet molding technology.

3DP technology:

3D printers using 3DP technology use standard inkjet printing technology to lay down liquid connectors on thin layers of powder, create each component layer by layer by printing cross-sectional data, and create a three-dimensional solid model. Using this The sample model printed by the technology has the same color as the actual product. The color analysis results can also be directly depicted on the model. The information conveyed by the model sample is larger.

FDM fused stacking molding technology:

FDM fused stacked molding technology heats and melts filamentary hot-melt materials. At the same time, the three-dimensional nozzle selectively coats the material on the workbench according to the cross-sectional profile information under the control of the computer. , forming a layer of cross-section after rapid cooling. After one layer of molding is completed, the machine table is lowered by a height (that is, the layer thickness) and then the next layer is molded until the entire solid shape is formed. There are many types of molding materials, and the molded parts have high strength and high precision. They are mainly suitable for molding small plastic parts.

SLA stereolithography technology:

SLA stereolithography technology uses photosensitive resin as raw material and uses a computer-controlled laser to scan the surface of the liquid photosensitive resin point by point according to the layered cross-sectional information of the part. The thin resin layer in the scanned area produces photopolymerization. Reacts and solidifies to form a thin layer of the part. After one layer of curing is completed, the workbench moves down a distance of one layer thickness, and then a new layer of liquid resin is applied on the surface of the originally cured resin until a three-dimensional solid model is obtained. This method has fast forming speed, a high degree of automation, can form any complex shape and has high dimensional accuracy. It is mainly used for rapid prototyping of complex, high-precision fine workpieces.

SLS selective laser sintering technology:

SLS selective laser sintering technology is to lay a layer of powder material (metal powder or non-metal powder) on the workbench in advance, and then let the laser sinter the solid part of the powder according to the interface contour information under computer control. Then it circulates continuously and builds up layer by layer. This method has a simple manufacturing process, wide range of material selection, low cost, and fast molding speed. It is mainly used in the foundry industry to directly produce rapid molds.

DLP laser molding technology:

DLP laser molding technology is similar to SLA stereo lithography technology, but it uses a high-resolution digital light processor (DLP) projector to solidify liquid photopolymer and perform photocuring layer by layer. Each layer is cured through a slide-like sheet, making it faster than similar SLA stereolithography technologies. The technology’s high molding accuracy rivals injection-molded durable plastic parts in terms of material properties, detail and surface finish.

UV ultraviolet molding technology:

UV ultraviolet molding technology is similar to SLA stereolithography technology. The difference is that it uses UV ultraviolet rays to irradiate liquid photosensitive resin and stack it layer by layer from bottom to top. No noise is generated during the molding process. The molding accuracy is the highest among similar technologies and is usually used in industries such as jewelry and mobile phone casings that require high precision.

Editor’s note: From the perspective of the principles of each 3D printing technology, the volume of 3D printing equipment and the cost of 3D printing, for individual consumers, equipment using FDM fused stacking molding technology has the lowest overall cost and the smallest footprint, so we can It can be seen that the 3D printers sold to ordinary consumers on the market are all based on FDM fusion stacking molding technology.

A brief history of 3D printing

In 1986, Charles Hull developed the first commercial 3D printing machine.

In 1993, MIT received a patent for 3D printing technology.

In 1995, the American company ZCorp obtained the sole license from MIT and began to develop 3D printers.

In 2005, the Spectrum Z510, the first high-definition color 3D printer on the market, was successfully developed by ZCorp.

In November 2010, Urbee, the world’s first car printed by a 3D printer, was launched.

On June 6, 2011, the world’s first 3D printed bikini was released.

In July 2011, British researchers developed the world’s first 3D chocolate printer.

In August 2011, engineers at the University of Southampton developed the world’s first 3D printed aircraft.

In November 2012, Scottish scientists used human cells to print artificial liver tissue with a 3D printer for the first time.

The range of applications of 3D printing is beyond people’s imagination. In theory, almost anything that exists can be copied by a 3D printer. As the technology continues to mature,MJF 3D printing technology is expected to be widely used in the following industries:

1. Traditional manufacturing: 3D printing is far superior to traditional manufacturing technology in terms of cost, speed and accuracy. 3D printing technology itself is very suitable for mass production. When the automotive industry performs safety testing and other work, some non-critical components can be replaced with 3D printed products to reduce costs while pursuing efficiency.

2. Medical industry: In surgical operations, 3D printing technology can “tailor-make” the organs needed for patients who need organ transplants without worrying about rejection. Printing a human heart valve only requires $10 worth of polymer materials.

3. Cultural relic protection: Museums often use many complex substitutes to protect original works from environmental or accidental damage. At the same time, replicas can also influence art or cultural relics to more and further people.

4. Architectural design industry: In the construction industry, engineers and designers have gradually begun to use 3D printers to print architectural models. This method is fast, low-cost, environmentally friendly, and beautifully produced, fully meeting the designer’s requirements, and at the same time Can save a lot of materials.

5. Accessories and jewelry industry: 3D printing technology can well meet the personalized and diverse needs of accessories and jewelry consumers. Some companies at home and abroad have begun to provide consumers with personalized 3D printing services.

Recently, Zhang Zhefeng’s team at Be-Cu Prototype Inc in China prepared a 3D printed titanium alloy material with high fatigue resistance. The research results were published in the magazine “Nature” on February 29, 2024.

Researchers believe that under ideal conditions, the titanium alloy structure (Net-AM structure) directly prepared by 3D printing technology should have natural ultra-high fatigue properties, but defects such as pores generated during the printing process conceal the fatigue resistance of its own structure. Advantages, resulting in a significant reduction in the actual measured fatigue performance of 3D printing materials. At the same time, the current process of eliminating pores is often accompanied by tissue coarsening, and the process of refining the tissue will bring new unfavorable factors such as the recurrence of pores, which can be described as a dilemma.

How to resolve this contradiction?

Researchers discovered for the first time in Ti-6Al-4V alloy that the grain boundary migration, pore growth and phase transformation processes of the 3D printed structure at high temperatures show asynchronous characteristics.

This means that there is a valuable heat treatment process window that can not only achieve lath structure refinement, but also effectively suppress the enrichment of α phase at grain boundaries and the recurrence of pores. To this end, the researchers cleverly took advantage of this process window, invented a new process for step-by-step control of defects and structures, and finally prepared Ti-6Al-4V alloy with almost no pores and a near-Net-AM structure. Its tensile-tensile fatigue strength increased from the original 475 MPa (MPa) to 978 MPa, an increase of up to 106%. Through comparison, it was found that this Ti-6Al-4V alloy with a near-Net-AM structure not only has the highest tensile-tensile fatigue strength among all titanium alloy materials but also has the highest specific fatigue among the material fatigue data that have been reported so far. Strength (fatigue strength divided by density).

“This achievement updates people’s previous inherent understanding of the low fatigue performance of 3D printing materials, reveals the unique advantages of 3D printing technology in anti-fatigue manufacturing, and demonstrates the important role of metal 3D printing materials as structural load-bearing parts in aerospace and other fields. It has broad application prospects in the field.” said the researchers. Be-Cu provides the highest standard of medical laser cutting and more 3D printing services for all your needs. Contact us today to learn more about what we offer!

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