3D Printing Aluminum

The 3D Printing industry is a versatile industry that can manufacture almost everything, and the materials used can be metal or non-metal. Among the metal materials used, aluminum alloys are used the most. 3D Printing technology can be used for all parts, items, instruments, etc. that can be manufactured by traditional techniques. Since 2019, the development of my country’s 3D printing industry has accelerated, and some products have been at the leading level in the world, but there is still some gap compared with advanced countries in general. By about 2025, it may become a global leader.

3D printing technology, also known as additive manufacturing, originated in the United States. It was originally developed by Charles Hoole in 1986 to develop light curing technology and set up 3D Systems. Since then, after more than 20 years of development, 3D printing technology has been perfected day by day, and sales of related products and services have continued to rise. According to Wohlers Associates, between 1992 and 2017, the compound annual growth rate of 3D printing products and related services business revenue was 25.4%. In the world, the country that produces and buys the most 3D printers is the United States, and my country has a small share. In 2020, the global 3D printing market share will reach about 12 billion US dollars, with the United States accounting for about 50%, Europe accounting for about 25%, my country and Japan each accounting for about 10%, and other countries and regions accounting for about 5%.

The 3D printing industry is a versatile industry that can manufacture almost everything, and the materials used can be metal or non-metal. Among the metal materials used, aluminum alloys are used the most. 3D printing technology can be used for all parts, items, instruments, etc. that can be manufactured by traditional techniques. Since 2019, the development of china 3D printing industry has accelerated, and some products have been at the leading level in the world, but there are still some gaps compared with advanced countries in general. By about 2025, it may become a global leader.

3D printed car engine block is available

In 2014, the world’s first 3D printed car was launched. More than 40 parts on the car’s body were printed from aluminum alloys. In 2015, American Divergent Microfactories (DM) launched the world’s first 3D printed supercar “Blade”.

In order to promote the application of 3D printing technology in the automotive industry, Ford Motor Company (Ford) and ExOne Company (ExOne) formed a research team composed of engineers, material scientists and manufacturing experts in 2019 to successfully 6061 aluminum alloy was used as the material and 3D printing technology to print the prototype of the engine block of the car. The performance of the prototype was better than expected, and more than 30% of raw materials were saved, and the manufacturing period was greatly shortened.

Alloy 6061 is a deformed aluminum alloy with a long history and good comprehensive properties. Its calibration composition (mass %): Si0.40-0.8, Fe0.7, Cu0.15-0.40, Mn0.15, Mg0.8-1.2 , Cr0.04-0.35, Zn0.25, Ti0.15, other impurities are individually 0.05, total 0.15, and the rest are Al. 6061 alloy is a kind of Al-Mg-Si alloy, its strengthening phase is Mg2Si, its Mg2Si content is ≥1.4%, 0.25% Cu is added in order to improve the strength performance, and 0.2% Cu is added to offset the adverse effect of Cu on corrosion resistance. %Cr. The alloy can obtain higher strength after heat treatment, but due to the high quenching sensitivity, it needs re-solid solution treatment and quenching in water after extrusion to obtain higher strength. The quenching temperature of 6061 alloy is 515℃-525℃. After quenching, it should be artificially aged as soon as possible (160℃-170℃, 8h-12h, T6) to obtain higher strength. It’s bad for strength. Alloys with more than 1% Mg2Si stored at room temperature for 24h have a strength about 10% lower than those aged immediately after quenching. This phenomenon is called “parking effect” or “aging lag phenomenon”. However, for alloys with less than 0.9% Mg2Si, the long standing time is beneficial to the strength. This effect is related to the nucleation ability of the vacancy-solute atom groups formed during parking at room temperature and the critical nucleation temperature TC. The Tc of high-concentration Al-Mg2Si alloy is greater than 170 °C, and the vacancy-solute group formed at room temperature is small, which cannot reach the critical size, and also causes the reduction of the supersaturation of the base. Therefore, only a small number of sized agglomerates can be formed during artificial aging. It is transformed into a precipitated phase, and because the concentration of the matrix decreases after forming agglomeration, a new crystal nucleus cannot be formed independently, so only a coarse precipitated phase and low strength can be obtained. On the contrary, when the parked low-concentration alloy is artificially aged, a precipitated phase with high dispersion is obtained, which is beneficial to the strength. This may be related to the different nucleation conditions of low-concentration alloys. Adding less than 0.4% Cu can alleviate the adverse effects of parking effect, because Cu can reduce the natural aging rate of AI-Mg-Si alloys.

Fe is a harmful impurity of AI-Mg-Si alloy, which is detrimental to strength. A small amount of Zn impurity has almost no effect on strength. Trace rare earth element RE can significantly improve the casting, processing and heat treatment performance of Al-Mg-Si alloy for conductive wire. Adding 0.1% RE to the Al-0.6Mg-0.6Si alloy not only improves the quality of the ingot, improves the wire drawing process, and improves the yield, it can be directly quenched after hot rolling, eliminating the solution treatment process, saving energy and labor. After aging (165℃/4h), the strength can be increased by about 15 MPa, and the resistance can be reduced by more than 2%.

Typical mechanical properties of 6061 alloy: tensile strength 316MPa, yield strength 281MPa, elongation 12%.

Typical 3D printed products in China

Be among the world’s leading ranks

In recent years, China has made remarkable achievements in 3D printing aluminum alloy products, and some 3D printing products have entered the world’s advanced ranks.

Aluminum alloy has excellent low temperature performance, and all mechanical properties increase synchronously with the decrease of temperature. It is an excellent material for manufacturing low temperature equipment. If Japan and the United States launch spacecraft with liquid hydrogen (-252.8°C) and liquid oxygen (-183°C), the fuel tank will be welded with 2219 alloy sheet, so the author believes that China’s liquid fuel tank and tank The connecting ring can also be made of 2219 alloy.

10m-class high-strength aluminum alloy heavy-duty launch vehicle connecting ring sample 2219 aluminum 3D printed part was released in January this year

The 10m-class high-strength aluminum alloy heavy-duty launch vehicle connecting ring sample is the world’s first 10m-class high-strength aluminum alloy heavy-duty launch vehicle connecting ring sample made by the China Additive Manufacturing Innovation Center and the team of Academician Lu Bingheng of Xi’an Jiaotong University using 3D printing technology. . The prototype uses the integrated manufacturing technology of arc fuse addition and subtraction materials, and has achieved major technological breakthroughs in the overall manufacturing process stability, precision control, and deformation and stress regulation.

The 10m-class super-large aluminum alloy ring is the key structural part connecting the barrel section of the heavy-duty launch vehicle storage tank, the front and rear bottoms and the rocket’s inter-tank section. The mass of the 10m-level super-large aluminum alloy ring is about 1t, and the multi-filament synergistic process equipment is used. The printing process is greatly simplified, the cost is greatly reduced, and the manufacturing cycle is greatly shortened, which only takes 30 days. At present, the use of the integrated printing technology of adding and subtracting materials is the first in the world to successfully complete a super-large ring. This achievement will help 3D printing continue to develop for China’s aerospace industry, and at the same time provide technical support for the rapid preparation of major parts in China’s aerospace industry.

3D printing wire can use 2219 aluminum alloy. 2219 aluminum alloy is an Al-Cu series high-strength aluminum alloy, which has been widely used in aerospace and defense industries. Its calibration composition (mass %): Si0.2, Fe0.3, Cu5.8-6.8, Mn0 .2-0.4, Mg0.02, Zn0.1, Ti0.02-0.1, V0.05-0.15, Zr0.1-0.25, other impurities are individually 0.05, total 0.15, the rest are AI, and now it has developed to 4 alloys , and the other three are 2319, 2419, and 2519.

The 2219 aluminum alloy was formed in 1985. The typical mechanical properties are shown in Table 1, and the relationship between mechanical properties and temperature is shown in Table 2.

The cladding alloy of the 2219 aluminum alloy sheet is 7072, and its composition (mass %): Cu0.1, Mn0.1, (Si+Fe) 0.7, Zn0.8-1.3, Mg0.1, other impurities individually 0.05, total 0.15, the rest is Al. The application temperature range of 2219 aluminum alloy is -269℃-300℃, which is one of the alloys with the widest application temperature range. The fracture toughness is also high, and the material has high resistance to stress corrosion cracking in the T8 state, and the density at 20 ° C is 2.84g/cm3.

The team of Academician Wang Huaming took the lead in breaking through the key technologies of laser 3D printing process, complete sets of equipment, internal quality and mechanical properties control and engineering application of large-scale key main bearing components such as aircraft titanium alloy and aluminum alloy in the world. The Component Additive Manufacturing Engineering Laboratory has achieved fruitful results after more than 20 years of unremitting research. Since 2005, 3D printing of titanium alloy and aluminum alloy aircraft fuselage main load-bearing frame, wing root rib, landing gear and other large-scale overall key load-bearing components has been widely used in domestic new generation fighter aircraft, large transport aircraft, launch vehicles and other aerospace major components. It has been widely used in equipment development and production. On January 16, 2016, the project “Laser Forming Technology for Large and Complex Components of Aircraft Titanium Alloy” chaired by Academician Wang Huaming won the first prize of the National Technology Invention Award.

At present, the manufacturing process of the dual-performance blisk technology mainly adopts the welding method, and the blades and discs with different performances are welded into a whole through linear friction welding and other technologies. However, the biggest disadvantage of the welding method is that the connection area often becomes the weak link of the whole component and becomes a fatal hidden danger of the engine. With the development and maturity of 3D printing technology, it has been proposed to print the blades directly on the disk body, and through the coaxial powder feeding laser cladding process, the bosses are pre-processed on the edge of the titanium alloy disk body, and the titanium alloy blades are stacked layer by layer. .

The first 3D printed landscape bridge in China will meet the audience on January 11, 2021 in the central green space of Taopu, Putuo District, Shanghai

The landscape bridge is the first pioneering attempt to use 3D printing technology in China’s construction engineering field to convert design blueprints into real objects and put them into practical use. 3D printing breaks through the shackles of bridge design and integrates parametric construction methods into it. It can not only create complex shapes, but also use molding technology to feedback calculations and interact with designers, making the design more free, flexible, and more flexible. Multiple spaces change.

The printing material used for this bridge is polymer PSA, but some glass fibers are added to improve the strength, and of course, aluminum alloy powder can also be used for printing. PSA has high weather resistance, elastic modulus, yield strength and impact strength, and can withstand long-term sun and rain, while meeting the requirements of 3D printing materials and building materials. The bridge is 15m long and is stacked layer by layer. It takes 8 hours to print one layer, and it can be completed with a thickness of 4mm and a length of 15m. The carrying capacity of the bridge is 250kg/m2, and at least 4 adults per square meter can cross the bridge at the same time.

In addition, in March this year, Shanghai also added two 3D printing bridges, one of which is concrete, in the Wisdom Bay Science and Technology Park at No. 6 Yunchuan Road. The bridge is 26.3m long and 3.6m wide, the longest bridge in the world. The bridge draws on the structure of the ancient Zhaozhou Bridge in China, and its shape is graceful. The overall project of the bridge uses 2 robotic arm 3D printing systems. It only took 450 hours to complete the manufacture, and the cost is also 34% lower than that of ordinary bridges, which greatly saves time, manpower and material costs.

The other 3D-printed bridge is China’s first retractable bridge, called the Wannian Ring. In July this year, it was installed in the “Starry Sky Elevated Park” in Science and Technology Bay, Baoshan Jiaoyun Wisdom Bay. The bridge body is printed from recyclable carbonated polyester composite material, with a length of 9.34m, a width of 1.5m, a height of 1.1m, and a total mass of 850kg. It can carry 20 adults and is divided into 9 stretchable segments, which only need to be opened and closed. 1min, can be controlled by mobile phone bluetooth. When the bridge deck is opened, the 9 panels are lined up in a row. When the bridge deck is folded, the 9 panels are folded in turn in the shape of a full moon. Especially at night, the LED lights in the panel armrests are very bright.

China is the only country in the world that has mastered the laser rapid prototyping technology of aircraft titanium alloy large-scale main load-bearing structural parts and realized the installed application.

In the development process of new military aircraft such as carrier-based aircraft and fourth-generation aircraft, 3D printing technology has played an important role, undertaking the trial production of titanium alloy and aluminum alloy main load-bearing components including landing gear. On May 5, 2020, China’s successful first flight of the Long March 5B carrier rocket was equipped with a new generation of manned spacecraft test ships, and there was also a “3D printer” on board. This is China’s first space 3D printing test, and it is also the first international 3D printing test of continuous fiber reinforced composite materials in space.

Typical products of foreign 3D printing aluminum alloy

One of the great advantages of 3D printers is their ability to make objects on the fly, another advantage is that the objects they make are customizable, so designs can be easily edited for personalization and adjustment.

  • Meld’s 6061 aluminum alloy ring. In 2019, the company used its original 3D printing technology to print a large ring with a diameter of more than 1400mm from manufacturing 6061 aluminum alloy powder, which is a milestone in the field of 3D printing. The ring is printed by a solid-state process, the material will not reach the melting temperature during processing, the residual stress in the product is very low, and the size and shape are very refined.
  • Russian 3D printed drones. In June 2015, Rostec built an aluminum drone prototype with 3D printing technology, with a printing time of 31h, a mass of 3.8kg, a wingspan of 2400mm, a flight speed of 90-100km/h, and an endurance of 1-1.5h. .
  • Boeing is the first international aerospace manufacturing enterprise to use 3D printing technology for aircraft design and manufacture. It has accumulated hundreds of different small parts using 3D printing technology. In 2012, General Electric Company (GE) acquired Morris Techno-logies, which specializes in developing laser-sintered metal powder technology, to make parts for its Leap line of engines. Pratt & Whitney has invested millions of dollars to establish a 3D printing center with the University of Connecticut. NASA is using 3D printers to produce spacecraft engine parts, and plans to launch printing equipment to the International Space Station, with the hope that astronauts can use the raw materials in the space station to directly produce the required items, changing the replenishment model that relies entirely on ground supplies.

The 3D printing technology market cannot be underestimated

According to Japanese data research firm Fuji Economic Research, the size of the global 3D printing market using resin and metal as raw materials will grow from 118.6 billion yen in 2019 to 183.3 billion yen by 2025, an increase of as much as 50% .

According to analysis by professional magazines, the number of 3D printing technologies used in 2020 has increased by six or seven times, and the United States, the United Kingdom, and Germany are the most used countries. In 2020 alone, more than 2 million 3D printers were sold, and they are expected to exceed 15 million by 2028. Printers are much cheaper, faster, and regulators are increasingly facilitating and supporting the adoption of the technology. The barriers that initially hindered the adoption of this technology are slowly disappearing. For example, the U.S. Food and Drug Administration has issued guidelines for 3D printing medical devices, and in Europe, commissioned processing services related to 3D printing are gaining ground.

However, it should be pointed out that despite the huge potential of 3D printing technology, it is far from being able to replace traditional processes in terms of existing technical conditions, and it is impossible to do so in the foreseeable period. For craftsmanship, it’s a great and powerful addition. Of course, from a long-term perspective, it is difficult to say, and it is very possible in individual fields. As The Economist said: The impact of great inventions was unpredictable at that time, the steam engine in 1750, the printing press in 1450, and the transistor in 1950. We still can’t predict how 3D printers will change the world over a long period of time.

The era of 3D printing has come

The construction of related projects should be followed closely

The era of 3D printing has really come, and many departments are fully prepared to keep pace with the world’s advanced level. In some fields, my country’s 3D printing has reached a leading level, such as China’s titanium alloy laser rapid The molding technology has been in the international leading position. Worldwide, the United States will still produce and purchase the most 3D printers in 2020, and my country will be the second largest country, surpassing Japan and Germany. According to the forecast of relevant institutions, before 2025, the global 3D printing industry will maintain an average annual growth rate of more than 20%. The author believes that China’s annual compound growth rate may reach 30% or higher.

According to statistics from relevant departments, the industrial applications of 3D printing technology are mainly in the fields of consumer electronics, automobiles, medical care, aerospace, construction, and scientific research. From the perspective of specific applications, 3D printing technology is still mainly used for the manufacture of design samples, display models and molds, and the proportion of direct parts processing has rapidly increased from less than 4% in 2003 to about 50% in 2020. It is estimated that the proportion will reach more than 80% in 2025.

At present, my country’s 3D printing industry has entered the parallel running stage from the follow-up stage before 2018, and will become the global leader in this industry in 2025. In order to achieve this goal, the author believes that the following points should be done:

●Strengthen investment and strengthen scientific research.

Build several national R&D units such as the National Engineering Laboratory and Research Institute of Metal Additive Manufacturing of Beihang University, and lead the elite team to carry out R&D with academicians or scientists, because the key to the development of the 3D printing industry lies in the development of talents. nourish.

Planned to establish some high-precision 3D printing enterprises under the guidance of the socialist market economy, such as the connecting ring of the spacecraft’s fuel tank, the upper and lower end caps, and even the box body can be printed with 2219 aluminum alloy, and the aircraft landing gear is zero. Parts can be printed with titanium alloy and aluminum alloy, and nearly 50 parts are manufactured by traditional technology for the entrance door of civil aircraft. If they are manufactured by 3D printing technology, they can be integrated into a large part; auto parts are even a big industry, and many parts can be built. For production lines, it is best to cooperate with automobile manufacturing companies to establish some 3D printing independent enterprises. It is also possible to build production workshops or production lines in existing aluminum processing plants, automobile factories, etc., whether it is a fuel vehicle or a new energy vehicle, there are many parts available for 3D printing. Process printing, many parts of the new energy vehicle engine can be printed with 3D process, and the battery box can also be 3D printed with aluminum alloy.

The automotive industry is one of the most important application areas of 3D printing technology, accounting for 25% of the world market share in 2020. From the perspective of specific use, it basically focuses on designing prototype manufacturing and mold processing in the production process, and most of the materials are aluminum alloys. With the aid of 3D printing technology to assist design and testing, it can significantly shorten the product development cycle and reduce the cost of trial production and testing. For example: General Motors (GM) has used 3D printing technology to print more than 50,000 parts and molds by 2020, South Korea’s Hyundai Motor Company (Hyundai) and Germany’s BMW (BMW) have also already applied 3D printing technology to New car development.

●The medical device and “bioprinting” market is promising

The medical industry is a market with a large demand for personalized customization, and it is difficult to carry out standardized and mass production, and this is precisely the advantage of 3D printing technology. Today, 3D printing technology has been successfully applied in the fields of hearing aid manufacturing, orthodontics and restoration, and prosthesis manufacturing, and it is quite mature. 3D printed dental bridges are more precise and precise, and are more convenient and faster than traditional preparation processes. Similarly, the use of 3D printing technology can well achieve the replication of the remaining limbs, and the manufactured prostheses are more human-like. As of 2020, more than 48,000 patients have used 3D-printed titanium alloy bones in Europe, and a hospital in the United States has replaced up to 75% of the patients’ damaged bones with 3D-printed skulls, which has no impact on the normal life of patients.

3D printing technology can also be used to understand patient conditions and assist in doctor-patient communication. For example, a 3D printer can print a three-dimensional skeleton model of a patient, and doctors can use the model to discuss the treatment process and communicate with patients about surgical plans; medical staff can also learn about the internal structure of a patient’s organs through 3D printed replicas, and can also perform operations on these replicas. Simulate surgery.

3D-printed models or inanimate prosthetics are just the beginning. The most fascinating thing is to directly print active tissues and organs, that is, “bioprinting”, specifically printing a skeleton, and then culturing stem cells on the skeleton to induce it to form tissues; A further method is to directly print tissues and organs for transplantation; even a step further is to directly print living tissues and living organs in the human body, and even the implantation process can be omitted.

●There are more and more 3D printing buildings in the world.

Buildings are big, but a house can be built in 10 days using 3D printing technology. 3D printing technology was originally mainly used for the manufacture of design models, but now complex structures can be printed, which greatly expands the imagination of designers. In January 2014, several 3D printed buildings were unveiled in Suzhou Industrial Park, including a 1100m2 villa and a 6-storey residential building. Their walls are spray-painted layer by layer by a large-scale 3D printer, and the “ink” used for printing is made of construction waste; on July 17, 2015, a 3D-printed modular new material villa appeared in Xi’an. This hardcover villa takes only 3 hours to print, as long as the furniture is placed, you can move in with a bag.

3D printing buildings will produce almost no construction waste, and each residential unit printed can reduce carbon emissions by 2-3t. Some architectural 3D printing systems can complete the work of 10-20 workers in many different industries, and can work 24 hours a day without rest, which can save developers more time and costs.

The above only introduces a few aspects of the application of 3D printing technology. In fact, there are countless items that can be printed, such as living robots, manufacturing various foods and beverages, artificial meat, etc. You can put a printer in the kitchen to make personalized food. 3D-printed vegetarian steak by Israel’s Redefine Meat; the number of components that can be printed in electronics is endless, the first 3D-printed laptop came out in 2015, and anyone can print it in their living room Own items, and the price is only 50% of traditional products; printing clothing and clothing, clothing made with 3D technology, not only has a novel appearance, but also fits comfortably. The designed and printed underwear and high-heeled shoes are very imaginative.

In a word, 3D printing technology is a kind of high-tech with great development potential, and my country attaches great importance to it. In August 2015, Li Keqiang, member of the Standing Committee of the Political Bureau of the CPC Central Committee and Premier of the State Council, presided over a special lecture by the State Council to discuss accelerating the development of advanced manufacturing and 3D printing. question. Since then, governments at all levels, enterprises and institutions have been earnestly implementing the instructions of the Party Central Committee and the State Council, vigorously developing 3D printing technology, and have achieved fruitful results. They have ranked among the world’s leading manufacturers in the manufacturing technology of many 3D printing products, but overall, There is still a certain gap with the United States, Germany, Japan, Israel and other countries, and there is still a gap to catch up, especially in terms of R&D and innovation. By 2025, my country will become the largest and most advanced country in the world with the most 3D printer manufacturing and 3D printing products in various fields.

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