This article is from the WeChat public account: TCT Asia Perspective (TCTAsia)
For 3D printing, whether it is metal, plastic or ceramic, it will affect everything from the use of support structures to shrinkage issues and the performance of the final part, but what if two completely different materials can be used for the final part?
The best example of this is undoubtedly the comparison between high-performance polymers (HPPs) and metals, where the properties and characteristics of polymers can rival those of many metal materials, making them a viable alternative. But what are the main differences between the two, and what should I pay attention to when printing? Next, TCT will combine overseas information to study these issues.
AON3D is a large part made using HPP
The difference between metals and high-performance polymers begins with their origins. While most metals are found in nature (with the exception of alloys, of course), polymers are man-made. In addition, the specific polymers used in 3D printing are made from chemically distinct polymer chains that are entangled.
While they may have been very different at the time of their birth, we think that the properties and characteristics of HPP are similar to those of metals. However, engineering plastics tend to have higher strength, purity, stiffness, abrasion resistance, and chemical resistance. These include thermoplastics such as ULTEM, PEKK, PEEK, etc.
While TPE/TPU, PC, and nylon are also sometimes classified as thermoplastics, they should be considered "engineering thermoplastics," while "high-performance" thermoplastics are in their own right. It is important to note that engineering materials, while not as good as metals or high-performance thermoplastics, are sufficient for certain applications and are less expensive. Users should accurately consider their own needs when choosing.
Different polymers have different classifications, as shown in the diagram, the pyramid is designed to slow down compatibility with SLS
There are also many types of metals used in additive manufacturing, including naturally occurring metals as well as alloys. Commonly used metals include aluminum and its alloys, steel (including stainless steel and tool steel), copper alloys, gallium, titanium and its alloys, cobalt-chromium-nickel-based alloys, and in recent years, even precious metals such as gold or silver. The type of metal used depends on the intended use of the end part, as each metal has different properties.
Both HPP and metals have mechanical, thermal, and chemical properties. In fact, high-performance thermoplastics are comparable to most metals, especially so-called "super" polymers such as PAEK (which includes all materials of the polyetherketone family, such as PEEK and PEKK) and PEI (better known by its brand name Ultem).
For example, PAEK materials are known for their excellent chemical, fluid, abrasion, temperature, and fire resistance. In addition, they have excellent thermal and mechanical properties and have high impact strength even at high temperatures or sub-zero temperatures. Not only that, but one of the biggest advantages of using high-performance polymers is their extremely high strength-to-weight ratio (even about 60-70% lighter than aluminum), which makes the component not only strong but also lightweight. The glass transition temperature also tends to be high, as is the elongation at break, although this varies between PEI, PEKK and PEEK. Corrosion resistance is also a significant advantage of all polymers compared to metals.
The difference in tensile strength between aluminum and ordinary HPP materials
On the other hand, there are indeed differences between different metals. For example, aluminum is weaker than many other metals, but much lighter. Copper, on the other hand, has electrical and thermal conductivity, as well as good ductility. Also, titanium is known for its biocompatibility, while cobalt is favored for its strength and ductility.
Overall, metals are popular for their strength and stiffness, and high-performance polymers are typically less dense than metals. Depending on the specific alloy used, metals also tend to be able to handle a wider range of temperatures. However, metal parts also tend to require more time and technical costs because the machining process involves lasers.
Some of the polymer exhibitors at TCT Asia 2024:
Polymaker, eSun, BASF Forward AM, Northberry, Yuanjia Biotech, Aidi Synthesis, Zhuhai Sanlu, Jufeng New Materials, Zhongshan Dajian, NatureWorks, Arkema, Guangzhou Yousu, Evonik, Alice, Leifus, Lexin Corning, Complexe High-tech, Hisun Biotech, Corbion, Hangzhou Zhuopu, Yongdian (in no particular order), etc
Some of the metal exhibitors at TCT Asia 2024:
Willari, Ningbo Zhongyuan, Jiangsu Jinwu, Nantong Jinyuan, Anhui Zhongti, Hegnass, Zhejiang Tianti, Feierkang, Academy of Military Sciences, Hebei Yibo, Liaoning Guanda, Hunan Aoke, Zhongtian Shangcai, Ningbo Shangcai, Shaanxi Dingyi, Xingchen Technology, Yinna Technology, Youyan Additive, Baoji Jiaqi, Xi'an Ouzhong, Gaoye New Materials, Xingguan New Materials, Panxing (in no particular order), etc
For more 3D printing material solutions, visit TCT Asia - Materials Zone on May 7-9, 2024 to find out. Scan the QR code now to register for an appointment and get free 50 yuan tickets.
Due to the nature of the material, the process used is also different. There are many more metal-compatible additive manufacturing technologies than high-performance polymers.
When it comes to metal powders, the most common processing methods are laser powder bed fusion processes, such as DMLS and EBM. Directed energy deposition (DED) processes, including many others such as WAAM, EBAM, and WAM, use wire or powder to fabricate or repair oversized metal parts (currently the only additive manufacturing process that can do this).
Many metal 3D printing processes involve lasers
In processes that do not use lasers, such as binder jetting technology, the binder is ejected to bind the powder together. However, due to its properties, this technique requires extensive post-processing, such as sintering after the initial printing. Then there is extrusion, which is only available from certain companies, in which the metal is printed along with a polymer matrix. However, debinding and sintering also need to be carried out before the part can be used.
In contrast, while standard polymers are compatible with a wide range of additive manufacturing processes, high-performance polymers are not. The main 3D printing production process for these materials is extrusion, which can be used either filaments or pellets (although filaments are more often used these days). SLS can also be implemented, but there are far fewer solutions available (especially EOS P810 machines), which work well as no support structures are required.
But it must be considered that high-performance polymers are not easy to print. Even if extrusion is the main process, not all FDM or FGF 3D printers are up to the task, and printers designed for high-performance thermoplastics must be used.
Parts made with high-performance polymers are often extruded
Not only that, but due to the nature of semi-crystalline polymers such as PEEK and PEKK, they can be unstable when melted, making it difficult for even professional users with equipment to print, especially since all high-performance polymers are prone to warping.
The similarity between metals and high-performance polymers also lies in the difficulties in the printing process: in a closed chamber and at high temperatures, both materials require a lot of work to print successfully. But even then, it is more difficult for the metal, because the machine needs to print in a closed chamber without oxygen, otherwise the oxygen will react with the metal during the printing process. To avoid this, the closed chamber must be filled with an inert gas such as argon.
Additionally, due to the use of lasers and the nature of metals, some people do believe that high-performance polymers are easier to print because there are fewer steps involved. Another example is that laser powder bed fusion requires additional safety measures and safety equipment, including respirators and protective clothing, to ensure that the powder does not enter the lungs or come into contact with the skin.
In the process of moving towards 100% recycled materials, the first consideration is to consider less reactive alloys such as stainless steel, nickel-based alloys or cobalt-based alloys. While these materials are easier to recycle, there is a strong interest in the recycling of highly reactive alloys, which are critical for defense and high-performance applications. Strategic considerations include volume availability, metal unit value, and powder demand, with nickel superalloys, titanium, and aluminum being promising starting points.
There is also a great deal of overlap in the application areas of HPP and metals. For example, both are used in industries such as aerospace, where high-strength, corrosion-resistant components are essential for large temperature changes and compliance with regulations for safety-critical components. HPP is lighter in weight compared to metal, which is very important in the aerospace sector.
In the automotive and transportation sector, WKW.automotive, a global supplier of aluminum profiles to automotive OEMs, has partnered with BASF Forward AM to provide innovative applications and solutions for the automotive industry with 3D printing metal materials and technologies.
BASF's Forward AM (booth no.: 8D50) Ultrafuse 17-4 PH metal wire and Ultrafuse®® Support Layer support wire are the perfect material for the production of prototype tools due to their high hardness, strength and stiffness, as well as mechanical properties that are superior to plastic materials. BASF Forward AM also offers metal debinding and sintering services, as well as the necessary post-processing solutions, such as polishing, to meet all tolerances and mechanical property requirements.
Medical applications are also important, but it is important to note that not all HPPs or metals are suitable for medical applications. Titanium is popular for its biocompatibility due to its universal antibody fluid corrosiveness, ability to bind to bone, and high limits. Polyetheretherketone (PEEK) has properties very similar to human bone, making the material particularly suitable for 3D printed implants.
Just in October 2023, Evonik (booth number: 7Q05) launched the world's first 3D-printed carbon fiber-reinforced PEEK filament for medical implants. According to Evonik, the new products are VESTAKEEP iC4612 3DF with 12% carbon fiber content and VESTAKEEP®® iC4620 3DF with 20% carbon fiber content, and users can choose according to the mechanical properties required for 3D printed implants such as bone plates and other artificial prostheses.
The high strength of carbon fiber and the excellent toughness of PEEK give VESTAKEEP iC4612 3DF and VESTAKEEP®® iC4620 3DF excellent mechanical properties. The carbon fiber arrangement of the carbon-reinforced PEEK filament can be controlled during the 3D printing process. The material is highly biocompatible and is ideal for metal allergy sufferers, while also being free of artifacts under X-rays.
Winwin is a 3D printed implant made of carbon fiber-reinforced polyetheretherketone (PEEK) filament material
Polymers are better suited for lighter parts and are superior in corrosive environments. In addition, they have effective thermal and electrical insulators, making them ideal for electrical applications. However, when it comes to strength regardless of weight, metal will have an advantage. Because the greater the range of options, the easier it is to select the material they need based on their specific properties. In addition, metals are electrically conductive, and while not suitable for applications that require insulation, they can be of great benefit in electronic components and wiring systems. This is also an element when creating sensors or biomedical devices.
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TCT Asia 2024
Time & Place
May 7, 09:00 - 17:30
May 8, 09:00 - 17:30
May 9, 09:00 - 15:00
National Exhibition and Convention Center (Shanghai) Hall 7.1 & 8.1