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The State of 3D Printing at Continental Automotive

Other organizations like NASA have also been using 3D printing technology for prototypes and functional parts—long before the rest of the world had an inkling about the impacts that would be made decades later in nearly every major industrial application. The Continental Automotive division serves as a good example of the long evolution of 3D printing and additive manufacturing within industries like automotive.

Selective Laser Melting (SLM) is used to print steel and aluminum. (Image credit: Claus Dick)

With a market cap of roughly $18.5 billion, Continental is a German multinational auto parts maker that manufactures such products as electronics; safety, powertrain and chassis parts; brake systems, tires, and more. Its customers run the gamut of car, truck and bus companies, including Volkswagen, Ford, Volvo, BMW, Toyota, Honda, Porsche and others.

As with every automaker, the firm has been using AM for design and prototyping purposes for some time, but it is now taking the technology to the next level. Just last year, the German-headquartered company opened the competence center for additive design (ADaM) at its Karben site. Five different 3D printing techniques are currently being used at ADaM:

Selective laser melting (SLM)
Selective laser sintering (SLS)
Stereolithography (SLA)
Digital light processing (DLP)
Fused deposition modeling (FDM)

“Practically at every location there are at least smaller additive systems, but this abundance and variety of systems is only available in Karben,” said Frauke Berger, site manager at Continental Automotive, in a recent interview.

Site manager Frauke Berger presents a printed component made of plastic. (Image credit: Claus Dick)

As the automotive and engineering divisions of the company, founded in 1871, work together closely, they are able to put the advantages of 3D printing into action using both plastic and metal materials.

For Continental, this means enjoying savings on the bottom line, more efficient manufacturing processes, ease in designing and making changes without waiting on a third party, and, most importantly for many industrial users, the ability to fabricate more complex geometries previously impossible with traditional techniques.

“A major advantage of additive manufacturing is that parts can be designed differently, and projects are therefore approached in a constructively different way,” said Berger.

Previously, the Continental team was able to create a more durable brake caliper:

“Usually such patterns come from sand casting. It takes about 14 weeks. The printed part was finished in less than a week,” explained Stefan Kammann, head of the Additive Design and Manufacturing business segment. “In principle, all weldable metals such as aluminum, stainless steel and tool steel, titanium or, to a limited extent, copper can be printed.”

Plastics are usually printed at Continental via selective laser sintering (SLS), as the team finds it to be the fastest route, as well as the most similar to ‘series technology.’ Materials such as PA12, as well as PA6, are often employed, along with polypropylene for parts like brake fluid containers.

As 3D printing and AM processes have continued to make impacts around the world and progress due to user’s needs, that growth has been seen at Continental, too, as software, hardware, and materials have been further refined. Orders for parts that may have previously involved up to 40 hours of production time now may take as little as 60 minutes.

“In the past we knocked the supports off the lattice platform with a hammer and chisel and had to be careful not to tear out any piece of the model, the material was so firm,” says Kammann. “The process is extremely precise, and we achieve good surfaces with it.”

With Selective Laser Sintering (SLS), support structures are no longer required. (Image credit: Continental)

DLP printing also allows for the option of 3D printing several parts at once, along with using a selection of materials, like ABS, PLA, TPU, and other plastics.

“For this purpose, a filament, i.e. a rolled plastic, is pressed through a hot nozzle and applied in sausages in a manner comparable to a CNC-controlled hot glue gun,” said Kammann. “You need an infrastructure and other technologies to process, combine, and instill the parts properly.”

Next year, the Continental team is planning to complete a large order for a manufacturer in need of 9,500 parts—all of which will be 3D printed.

Stefan Kammann explains how the rolled plastic is pressed through a hot nozzle. (Image credit: Claus Dick)

Industrial users continue to enjoy the positive impacts of 3D printing and AM processes in a wide variety of other applications too such as aerospace, dental and medical, construction, and far more.

What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

The Continental Competence Center for Additive Design and Manufacturing (Adam) in Karben houses various systems for 3D printing. (Image credit: Claus Dick)

[Source / Images: Automotive IT]

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CSIRO 3D Prints First Self-Expandable Stents from Shape-Memory Alloy Nitinol

Peripheral Arterial Disease (PAD) is a condition which sees fatty deposits collect and lower the blood flow in arteries outside of the heart, most commonly in the legs. Those suffering from PAD will often experience pain while walking, and could even develop gangrene if the case is serious enough. Over 10 percent of people in Australia are afflicted with this painful condition. To treat it, a stent can be temporarily inserted inside the blood vessel to keep it open.

We’ve seen 3D printing used to fabricate stents before, which can help improve sizing options and allow for patient-specific diameters and shapes. But ,until now, there hasn’t been a way to print a self-expandable stent made of shape-memory nickel and titanium alloy nitinol. The material is superelastic, and metallurgists have had a difficult time trying to figure out a way to 3D print a self-expandable nitinol stent without compromising the unique properties of the metal alloy.

But researchers from Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), together with its Wollongong-based partner, the Medical Innovation Hub, have finally made it possible.

Vascular surgeon Dr. Arthur Stanton, the Chief Executive of Medical Innovation Hub, explained, “Currently, surgeons use off-the-shelf stents, and although they come in various shapes and sizes, overall there are limitations to the range of stents available. We believe our new 3D-printed self-expanding nitinol stents offer an improved patient experience through better fitting devices, better conformity to blood vessel and improved recovery times. There is also the opportunity for the technology to be used for mass production of stents, potentially at lower cost.”

Stent model

The first 3D-printed nitinol stent is a major medical breakthrough for PAD patients, as surgeons have had to use off-the-shelf, non-custom stents for these procedures in the past. But with 3D printing, individual nitinol stents can be made right at the hospital, with the surgeon there to offer instructions—saving time and money, and reducing inventory, as well.

According to Australia’s Minister for Industry, Science and Technology, Karen Andrews, 3D printing could mark a major paradigm shift in the $16 billion worldwide stent manufacturing industry:

“This is a great example of industry working with our researchers to develop an innovative product that addresses a global need and builds on our sovereign capability.”

The proof-of-concept stents offer the potential for customization to individual patient requirements, but are equally as suitable for mass production.

Back in 2015, CSIRO opened the Lab22 Innovation Center. The specialist researchers there are focused on creating value for Australia’s manufacturing industry by developing future developments in metal additive manufacturing. CSIRO’s Lab22 collaborates with industry partners, like the Medical Innovation Hub, to build important biomedical parts, like the first 3D-printed sternum and titanium heel, and now the first 3D-printed nitinol stent.

CSIRO Principal Research Scientist Dr Sri Lathabai said, “Nitinol is a shape-memory alloy with superelastic properties. It’s a tricky alloy to work with in 3D printing conditions, due to its sensitivity to stress and heat. We had to select the right 3D-printing parameters to get the ultra-fine mesh structure needed for an endovascular stent, as well as carefully manage heat treatments so the finished product can expand as needed, once inside the body.”

The team used selective laser melting (SLM) technology to successfully fabricate the complex mesh stent structures. Due to the level of geometric accuracy that 3D printing achieves, the stents can be made for specific patients, and nitinol allows them to expand once inside the body. CSIRO has established a new technology company, Flex Memory Ventures (FMV), to help commercialize the technology.

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Investigating Properties of Virgin, Sieved, and Waste 316L Metallic Powder for SLM 3D Printing

We often see metal 3D printing used to make steel parts, so plenty of research is being done regarding the material properties. Researchers from VSB – Technical University of Ostrava in the Czech Republic published a paper, “Research of 316L Metallic Powder for Use in SLM 3D Printing,” about investigating Renishaw’s AISI 316L powder for use in Selective Laser Melting (SLM) technology.

“Understanding the SLM process is extremely challenging, not only because of the large number of thermal, mechanical and chemical phenomena that take place here, but also in terms of metallurgy. The presence of three states (solid, liquid, gaseous) complicates the ability to analyze and formulate a model formula for proper simulation and prediction of part performance when printed,” they explained. “Since the SLM process operates on a powder basis, this process is more complicated by another factor compared to the use of other bulk material. The properties of the used printing powder define to a large extent the quality of the finished part.”

Because the material can impact an SLM 3D printed part’s final properties, powder research should be done ahead of time for best results. Particle size, shape, flowability, morphology, and size distribution are key factors in making a homogeneous powder layer, and using gas atomization to produce spherical particles helps achieve high packing density; this can also be improved with small particles.

The researchers investigated three phases of metallic powder present in the SLM process – virgin powder (manufacturer-supplied), test powder that had been sieved 30 times, and waste powder “that had settled in the sieve and was no longer being processed and disposed of.” They used a non-magnetic austenitic stainless steel, alloyed with elements like nickel and chromium and containing a low percentage of carbon.

Scanning electron microscopy (SEM) was used to investigate the powder morphology, which “affects the application of metal powder by laser in terms of fluidity and packing density.” First, the shape of the powder particles was measured and evaluated, and then a visual quality evaluation was completed to look at the spherical quality and satellite (shape irregularity) content. The team found that many particles had satellites, but that this number increased in over-sized powder.

Fig. 1. SEM image of virgin powder 316L, magnification x180

“The measurement of virgin powder (Fig. 1) reveals that the production of powder by gas atomization is not perfect and the shape of some particles is not perfectly spherical,” the researchers wrote. “It is also possible to observe satellites (small particles glued to larger ones, Fig. 2), which are again a defect of the production method.”

Fig. 2. Satellite illustration, magnification x900

They found that the particle shape was “not always isometric,” and that cylindrical, elongated, and irregular shapes appeared alongside spherical particles in over-sized powders.

“Another interesting phenomenon was manifested in the sieved powder, where particles with a smoother and more spherical surface were observed than the original particles. This is most likely due to the melting and solidification process that is specific to AM,” they noted.

Fig. 3. Morphological defects – a) particle fusion; b) gas impurities; c) agglomeration – sintered particle;
d) dendritic particle structure; e) spherical particle; f) particles with a satellite

An optical method was used to measure powder porosity. The 316L powder was embedded in a resin, and was “1 mm layer abraded” post-curing before the particles were cut in half and polished with diamond paste. The images captured via microscope were loaded into analysis software, which determined that the total density of the powder was 99.785%.

“In general, pores must be closed from 3/4 of their circumference to be considered pores,” the team explained. “Particles that do not comply with this rule are automatically considered irregular particles.”

Fig. 4. An example of open pores that correspond to the rule (L), and pores that do not conform (R)

The researchers also measured the size of all individual pores and recorded which ones began at 5 µm, though they noted that due to potential image resolution issues, “pore sizes of about 5-8 μm should be taken with some uncertainty.”

Fig. 5. Pore size measurement of 316L metallic powder

A histogram showed that, in the metallic powder particles, the “15 µm pore size was most present,” and that the largest was 30 µm.

Table 3. Measured values of porosity of powder particles

Finally, they used an optical method to measure and examine grain size distribution of the virgin and sifted powder. Using 200x magnification, measurements were taken at five random locations, each of which had roughly 200 particles on which they performed static analysis. The results were processed with statistical software, which created cumulative curves to indicate how many particles were smaller or larger than a certain size.

“Of these, the quantiles d10, d50 and d90 were obtained, which express the cut-off limit within which the size falls to 10, 50, 90 % of the measured particles,” they wrote.

The average particle size only increases a little by repeatedly sieving the metallic powder, but because of irregular particles, agglomerated or molten particles larger than 45 μm, they fall through the mesh. Results show that <10 µm particles are reduced, while larger particles are increased, in the sift powder. But, the team notes that the powder is still usable.

“The sift powder showed an increase in particle volume and surface area while circularity decreased, indicating that virgin powder generally has a higher sphericity,” the team explained.

They found defects like agglomeration, gas impurities, and particulate fusions at all three stages, but since the powder is still usable, they concluded that SLM is both an economic and ecological technology. The researchers listed several measures to take in order to “achieve the best possible consolidation,” such as high purity, fine surface, low internal porosity, tight particle distribution, and as few surface pores and satellites as possible.

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Texas A&M: A Method for 3D Printing Porosity Free Martensitic Steels

While seeking a corrosion-resistant alloy for gun barrels in 1912, British researcher Harry Brearley, who is commonly regarded as the inventor of stainless steel, discovered a martensitic stainless steel alloy. Although several variants of steel exist today, this type particularly stands out from its steel cousins as stronger and more cost-effective to produce. The renowned metallurgist probably never thought that his breakthrough discovery would go beyond developing affordable cutlery to the masses, well into applications in the aerospace, medical, automotive, and defense industries. Now over 100 years later, it can also be used as a metal 3D printing material for complex designs.

However, for these and other applications, the metals have to be built into complex structures with minimal loss of strength and durability, which is why researchers from Texas A&M University, in collaboration with scientists in the Air Force Research Laboratory, have developed guidelines that allow 3D printing of martensitic steels into very sturdy, defect-free objects of nearly any shape.

Reported in the scientific journal Acta Materialia, the findings of their study suggest that the process optimization framework introduced is expected to allow the successful printing of new materials in an accelerated fashion and introduces the process parameters for building porosity-free parts.

Although the procedure developed was initially for martensitic steels, the researchers said they have made their guidelines general enough so that the same 3D printing pipeline can be used to build intricate objects from other metals and alloys as well.

“Strong and tough steels have tremendous applications but the strongest ones are usually expensive — the one exception being martensitic steels that are relatively inexpensive, costing less than a dollar per pound,” said Ibrahim Karaman, Chevron Professor and head of the Department of Materials Science and Engineering at Texas A&M. “We have developed a framework so that 3D printing of these hard steels is possible into any desired geometry and the final object will be virtually defect-free.”

A flowchart summarizing the framework, introduced in this study (Credit: An ultra-high strength martensitic steel fabricated using selective laser melting additive manufacturing: Densification, microstructure, and mechanical properties)

The high-strength, lightweight, and cost-effective martensite steels are formed when steels are heated to extremely high temperatures and then rapidly cooled. The sudden cooling unnaturally confines carbon atoms within iron crystals, giving martensitic steel its signature strength.

Texas A&M claimed that to have diverse applications, martensitic steels, particularly a recently discovered type of low-alloy, ultra-high-strength martensitic steel known as AF9628, need to be assembled into objects of different shapes and sizes depending on the particular application they will be used for, and that’s when additive manufacturing (AM) offers a practical solution.

Stainless steels can be used to 3D print complex designs that are normally impossible to fulfill. 3D printing methods initially used by the team to build complex items were direct metal laser sintering (DMLS) aka selective laser melting (SLM) and also known as Powder Bed Fusion. However, Texas A&M researchers detected that 3D printing martensitic steels using lasers can introduce unintended defects in the form of pores within the material. Moreover, they detected that there is currently no known work describing process-structure-property relationships for AF9628 in the context of AM, something they considered should be systematically studied, focusing on the effects of AM process parameters on the microstructural evolution and resulting mechanical properties of this new martensitic steel.

“Porosities are tiny holes that can sharply reduce the strength of the final 3D printed object, even if the raw material used for 3D printing is very strong,” Karaman said. “To find practical applications for the new martensitic steel, we needed to go back to the drawing board and investigate which laser settings could prevent these defects.”

In an effort to produce high strength parts with a high degree of control over geometry, the researchers presented the effects of the SLM parameters on the microstructure and mechanical properties of the new steel AF9628.

For their experiments, Karaman and his team first chose an existing mathematical model, called Eagar-Tsai, inspired from welding to predict the melt pool geometry, that is, how a single layer of martensitic steel powder would melt for different settings for laser speed and power. By comparing the type and number of defects they observed in a single track of melted powder with the model’s predictions, they were able to change their existing framework slightly so that subsequent predictions improved.

They claim that after a few of these iterations, their framework could correctly forecast, without needing additional experiments, if a new, untested set of laser settings would lead to defects in the martensitic steel.

Raiyan Seede, a graduate student in the College of Engineering at Texas A&M and the primary author of the study, explained that “testing the entire range of laser setting possibilities to evaluate which ones may lead to defects is extremely time-consuming, and at times, even impractical. By combining experiments and modeling, we were able to develop a simple, quick, step-by-step procedure that can be used to determine which setting would work best for 3D printing of martensitic steels.”

Seede also noted that although their guidelines were developed to ensure that martensitic steels can be printed devoid of deformities, their framework can be used to print with any other metal. He said this expanded application is because their framework can be adapted to match the observations from single-track experiments for any given metal.

“Although we started with a focus on 3D printing of martensitic steels, we have since created a more universal printing pipeline,” Karaman indicated. “Also, our guidelines simplify the art of 3D printing metals so that the final product is without porosities, which is an important development for all type of metal additive manufacturing industries that make parts as simple as screws to more complex ones like landing gears, gearboxes or turbines.”

Backscattered electron images of the etched cross-sections of AF9628 ultra-high strength martensitic steel as-printed cubes. The yellow dotted lines indicate melt pool boundaries (Credit: An ultra-high strength martensitic steel fabricated using selective laser melting additive manufacturing: Densification, microstructure, and mechanical properties)

This research, funded by the Army Research Office and the Air Force Research Laboratory, reports a successful methodology to determine optimal processing parameters, like laser power, laser scan speed, and hatch spacing, in selective laser melting AM in order to fabricate porosity-free parts.

The team of researchers effectively used it to fabricate fully dense samples over a wide range of process parameters, allowing the construction of an SLM processing map for the new martensitic steel alloy AF9628. Given the potential of this new high-performance steel, useful for machine tool components, structural components for aircraft gear, automotive parts, and even for ballistic armor plates, creating a new framework offers the potential to 3D print this new material much quicker, providing a powerful tool to many industries.

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Researchers Compare Microstructure of As-Cast, Hot-Extruded, and 3D Printed Magnesium Alloy Samples

Fig. 1: SEM micrographs of the WE43 alloy powder

Alloys of the shiny gray chemical element magnesium (Mg) feature a high strength-to-weight ratio and a low density of about 1700 kg/m3, making them good options for technical applications in the automotive, aviation, and medical fields. But it’s been determined that their weight can be further decreased if porous structures are formed – which can be achieved with 3D printing. A team of researchers from the University of Chemistry and Technology Prague and the Brno University of Technology, both in the Czech Republic, wanted to study the microstructure of a particular magnesium alloy after it had been fabricated using three different methods: as-cast, hot-extruded, and 3D printed with SLM technology.

SLM 3D printing can achieve complex geometric shapes, but there are issues when it comes to fabricating magnesium alloys with this process, mainly high reactivity of magnesium powder, which can lead to unsafe oxide particles forming within 3D printed parts. Patrícia Krištofová, Jiří Kubásek, Dalibor Vojtěch, David Paloušek, and Jan Suchý recently published a study, titled ” Microstructure of the Mg-4Y-3RE-Zr (WE43) Magnesium Alloy Produced by 3D Printing,” about their work mapping an SLM 3D printed magnesium alloy’s microstructure.

“Magnesium alloys made in the form of 3D printing are relatively new production processes,” the researchers wrote. “The study therefore this process compared with current processes, which are now well known and mapped. It was therefore studied the microstructure produced by three different processes of production. The microstructure and chemical composition of present phases were studied using scanning electron microscopy (SEM) and energy dispersive xray spectrometry (EDS). Based on the microstructural examination, significant differences were found between the materials produced by different production processes. The microstructure of the as-cast alloy consisted of relatively coarse α-Mg dendrites surrounded by eutectics containing intermetallic phases rich-in alloying elements. During hot extrusion, the eutectics fragmented into fine particles which arranged into rows parallel to the extrusion direction. The 3D printed alloy was characterized by significantly refined microstructure due to a high cooling rate during the SLM process. It consisted of very fine dendrites of α-Mg and interdendritic network enriched-in the alloying elements. In addition, there were also oxides covering original powder particles and the material showed also some porosity that is a common feature of 3D printed alloys.”

The team used an SLM Solutions 280HL 3D printer to fabricate 15 × 5 × 60 mm rectangular samples of WE43 magnesium alloy, and used SEM and EDS to study their microstructures; then, these were compared to identical materials that had been manufactured through simple gravity casting and hot extrusion.

“The first sample was an as-cast ingot of 60×80×500 mm in size purchased from an industrial supplier. The second WE43 alloy sample was prepared by hot extrusion of the ingot. Cylinders with a diameter of 30 mm and a length of 60 mm were directly cut from the ingot and then extruded at 400°C, extrusion rate of 2 mm/s and extrusion ratio of 16. The resulting extruded rods had a diameter of 7.5 mm,” the researchers explained.

“The analysis revealed that 10% of the WE43 alloy powder particles had a size of 26.9 μm, 50% to 39.8 μm and 90% to 57.9 μm. Thus, the powder contains a sufficient amount of both larger and smaller particles. With respect to the particle size, the size of the building layer was 50 μm.”

The team conducted microscopic observations of the samples, and you can see the views of their microstructures in Figure 2.

Fig. 2: SEM micrographs of the WE43 alloy: a) as-cast, b) hot extruded, c) 3D printed by SLM, d) 3D printed by SLM – detail.

The as-cast alloy has a coarse microstructure, while the microstructure of the sample fabricated with hot extrusion was “considerably” modified. The microstructure of the 3D printed sample is completely different from the other two, featuring regions about 20-50 µm in size that are surrounded by thin boundaries.

“In addition, residual porosity is observed as dark areas between grey regions. The shape and size of grey regions indicates that these regions correspond to original powder particles, either totally or partly melted by laser beam,” the researchers explained. “A more detailed image in Fig. 2d shows very fine internal microstructure of these particles. It contains α-Mg dendrites (dark) surrounded by interdendritic regions (light) enriched in Y and RE elements. The average thiskness of dendritic branches is only approx. 3 µm, suggesting very high cooling rates during the SLM process. In literature focused on the SLM process, cooling rates of 103-106 K/s are often reported.”

The researchers also studied the distribution of elements in the material’s structure, which showed that both the hot-extruded and as-cast material samples had very low oxygen concentration. But the SLM 3D printed sample showed a different story, illustrated in Figure 5 and Table 4.

Fig. 5 Microstructure of the SLM WE43 alloy (SEM) and elements distribution maps (EDS).

“First, element maps and point analysis demonstrate an increased concentration of oxygen in the material which is located mainly in pores (point 1) and also at bondaries between melted powder particles. In the particle interior the O-concentration is very low (point 2),” the researchers wrote. “Second, element map in Fig. 5 also indicates increased content of Y at powder particle boundaries. It can be assumed, that partial oxidation of the powder occurred during the SLM process inside the building chamber. Most probably, the atmosphere contained traces of residual oxygen which reacted preferentially with yttrium due to a high chemical affinity of these elements. For this reason, imperfect connection between powder particles and porosity are observed.”

Results show that an SLM material’s microstructure is “extremely fine” because of high cooling rates, and will also feature a high oxygen concentration “due to a high affinity of the alloy to this gas.” This creates an “imperfect connection” between powder particles and porosity. The researchers plan further studies of this magnesium alloy in order to produce pore-free compact material and decrease the “harmful influence of residual oxygen.”

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3D Printing News Briefs: May 26, 2019

This year’s RAPID + TCT ended late last week at the Cobo Center in Detroit, so we’re again starting off today’s 3D Printing News Briefs with more news from the busy show floor. DyeMansion launched a new extended color series at RAPID, while 3D Systems made the announcement that its Figure 4 Modular is now available. Moving on, SLM Solutions just celebrated the grand opening of its new Shanghai application center. Finally, a Reddit user made an adorable miniature 3D printer.

RAPID 2019: DyeMansion’s New Colors

DyeMansion at RAPID 2019 [Image: Sarah Saunders]

Munich startup DyeMansion, a leader in finishing and coloring solutions for 3D printing, launched its new ColorsX extended color series for end-use products at RAPID last week, in order to continue helping its customers achieve the perfect finish for all of their applications. Automotive ColorsX and Neon ColorsX are the first solutions under the startup’s X Colors for X Industries premise, with more to follow in the future. The automotive color line has improved light and heat resistance for better 3D printed polyamide components and interior car parts, and features Automotive BlackX, which has a less saturated black tone than DyeMansion’s basic DM Black 01 and was created according to ISO EN 105 B06 method 3’s hot irradiation standards. The luminous neon color line includes GreenX, YellowX, OrangeX and PinkX to help create striking end-use products. Both of these new color lines are compatible with DyeMansion’s PolyShot Surfacing (PSS) and VaporFuse Surfacing (VFS).

“Some of our earliest customers who made use of DyeMansion Print-to-Product technologies for serial production are from the Automotive and Lifestyle industries,” explained Kai Witter, DyeMansion’s Chief Customer Officer. “While working closely with our customers, joint strategies are always about creating even more value to their businesses. So, I feel very delighted to now offer additional value creating products. Automotive and Neon ColorsX are only the beginning of providing more specific industry offers.”

Once DyeMansion decided to launch its ColorsX series, it also named the coloring process it established back in 2015: DeepDye Coloring (DDC), which can be easily controlled and traced through integrated RFID technology and offers a limitless choice of custom colors.

RAPID 2019: 3D Systems Announces General Availability of Figure 4 Modular

Also at RAPID last week, 3D Systems announced the general availability of its scalable Figure 4 Modular production platform. The flexible digital light printing (DLP) system has multiple configurations that can print parts with high surface quality, and allows manufacturers to iterate designs more quickly, as well as produce end-use parts without having to worry about a minimum order quantity. Three models make up the Figure 4 – Standalone, Production, and Modular – and several customers, such as D&K Engineering and Midwest Prototyping, are reaping the benefits. Additionally, 3D Systems also announced five new DLP and SLS materials, the first of which is the immediately available Figure 4 FLEX-BLK 10. The other new Figure 4 materials, such as TOUGH-BLK 20, MED-AMB 10, MED-WHT 10, and HI-TEMP-AMB 250, are expected to be available in Q3 and Q4 of 2019.

“The newest additions to our plastic 3D printing portfolio demonstrate our commitment to driving the adoption of digital manufacturing. With the industry’s first, truly scalable plastic production platform and our robust selection of materials, 3D Systems enables customers to rethink manufacturing and realize improved agility, reduced complexity, and lower overall total cost of operation,” said Vyomesh Joshi, the President and CEO of 3D Systems.

3D Systems also announced that its customers Rodin Cars (based in New Zealand) and North Carolina-based Stewart-Haas Racing are using its plastic and metal 3D printing solutions to improve the speed and performance of their cars.

SLM Solutions Celebrates Opening of New Shanghai Application Center

The same year that SLM Solutions opened an applications and demonstration center in Germany, it also established Chinese operations in Shanghai. Earlier this week, the selective laser melting experts celebrated the grand opening of their expanded office facilities and application center in Shanghai, which will help the company continue to grow its presence on the Asian market. The new center has installed four SLM systems: one SLM 125, one SLM 500, and two SLM 280 printers. Additionally, the facility also has equipment to represent an SLM build’s supporting process chain, such as a metallurgical lab and post-processing capabilities. The grand opening included a tour through the new new customer service and application engineering center.

“As we continue to grow our Chinese team, the opening of our Shanghai Application Center is an important milestone in SLM Solutions’ development and indicates the confidence in the Chinese market,” stated Jerry Ma, General Manager of SLM Solutions (Shanghai) Co., Ltd. “As part of the global strategy for growth we have the capacity to more than double our number of employees and the equipment to support all Chinese users with the technological resources shared by our applications centers around the world. We can also provide high-quality, fast technical services to better promote the development of selective laser melting and create more value for customers.”

Mini 3D Printed 3D Printer

A reddit and imgur user by the name of “Mega Andy” used 3D printed parts and DVD drive motors to make his own miniature 3D printer. And by miniature, I mean that he used a banana for scale, which was taller than the 3D printed 3D printer itself! It’s a really interesting project – the device runs Marlin, and features a glass bed and an E3D V6 hotend. The black and gold parts of the mini 3D printer were made out of PLA material, while PETG was used to make teeth for the leadscrews. Speaking of this, Mega Andy said that the printer is “fairly unreliable” because it easily ruins the teeth that guide the device on the leadscrew. Additionally, he’s also working to improve and lengthen the Z axis due to binding problems. Mega Andy released the STLs onto Thingiverse so others could try to make their own versions of the miniature 3D printed 3D printer…say that five times fast.

“So this project is nothing new, people have made 3d printers, CNC, engravers before using this hardware. What I wanted to do differently with this is have a designed 3D printed frame to hopefully fit standard parts. Instead of mounting full metal dvd drive assembly’s together and look like a DIY project I wanted a something that could be more compact and neat,” Mega Andy wrote on Thingiverse.

“This project is not for everyone and would only recommend to someone with a decent knowledge of 3d printers, basic soldering and lots of patience. Also some fiddling was needed to get the right amount of tension on the leadscrew, this bit is a massive pain but hopefully no one else needs to go through quite as much issues as i did with this bit. They will wear out though and a 3d printer will be needed to print new parts for it when they inevitable wear out.”

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SLM Solutions Helping to Create Guidelines for 3D Printing Spare Parts in Oil, Gas, & Maritime Industries

Last January, 11 companies – now at a total of 16 – began working together on two aligned Joint Innovation Projects (JIPs). Their objective – collaborate in developing a guideline for 3D printing functional, qualified metal spare parts for the Oil, Gas, and Maritime industries, in addition to creating an accompanying economic model.

The 16 companies working on Joint Innovation Projects (JIPs). [Image: SLM Solutions via Facebook]

These 16 partner companies participating in the standardization project include:

In addition, SLM Solutions, a top metal 3D printing supplier headquartered in Germany with multiple offices around the world, is also working to support these two joint projects.

“Our aim is to make the SLM technology better known in the industry and to increase its application through uniform standards,” stated Giulio Canegallo, Director of Business Development Energy for SLM Solutions, who is representing the company in the JIP.

The company offers cost-efficient, fast, and reliable Selective Laser Melting (SLM) 3D printers for part production, and works with its customers throughout the process in order to offer expertise and support. It will be supporting the JIPs by offering its technical 3D printing expertise, for SLM additive manufacturing in particular.

Using pilot parts, like this pump impeller 3D printed on the SLM 280, the guideline is tested for practical application.

Together with the other 15 JIP partner companies, SLM Solutions is working to create two separate but aligned, coherent programs: a toolbox that will enable economic viability, selection, and supply chain setup, to be be managed by Berenschot, and a guideline towards certified parts, which will be manged by DNV-GL.

Because these two programs will be aligned in their setup, the companies can ensure, as SLM Solutions put it, “maximum cross fertilization.” In order to make sure that all the steps are there to achieve high quality, repeatable production, up to five pilot parts will be produced for the JIPs. One of these pilot parts is a pump impeller, which SLM Solutions already fabricates on its SLM 280 3D printer for oil and gas company Equinor.

During production of the selected pilot parts, the partner companies will complete a final applicability test of this guideline, focusing specifically on its practical use in successfully producing the parts, and their overall quality. The information that’s learned in these case studies will be added to the guideline’s final version so that others can benefit.

The practical guideline will be available to use by this coming June, and will offer a framework so users can make sure that their 3D printed metal spare parts, fabricated through either SLM or Wire Arc Additive Manufacturing (WAAM) technology, will conform to the exacting specifications of the Oil, Gas, and Maritime industries.

A functional, comprehensive business tool will also be released in June, to help figure the bottom-line impact that will result from using 3D printing to fabricate spare parts, as opposed to more conventional methods of manufacturing. A database of parts will also be put together in cooperation with the business ROI-model, in order to show just how applicable 3D printing is for manufacturing spare parts for these three industries. The model will be officially tested during the Q2 parts production process.

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TU Delft Researchers Develop Heat Accumulation Detection Procedure for SLM 3D Printing

Selective Laser Melting (SLM), a powder-based 3D printing technique also known as Laser Beam Melting or Laser Powder Bed Fusion, has been used to process metal in a variety of sectors, such as automotive, medical, and aerospace. Because this AM method offers excellent freedom of form, it’s a perfect enabling technology for designs that are topology optimized; this means they have a complex layout, but still offer a superior performance. But, SLM 3D printers don’t always realize the dimensional accuracies that are necessary for very precise components.

Because of laser-induced heat, SLM 3D printed layers go through stages of rapid heating-cooling, which can cause inaccuracies, such as unwanted mechanical properties and poor surface finish. If certain design features, like thin sections and overhangs, that can cause local heat accumulation could be detected earlier in the design stage, this issue could be avoided more easily. To do this, next generation topology optimization (TO) methods need to be developed.

A group of researchers from TU Delft recently published a paper, titled “Towards Design for Precision Additive Manufacturing: A Simplified Approach for Detecting Heat Accumulation,” focused on a simper heat accumulation detection procedure – very important for creating a TO scheme that can account for thermal 3D printing aspects.

“In order to address thermal aspects of AM into a TO framework, an appropriate AM process model is required. This becomes problematic because a high fidelity AM process model is computationally very expensive and integrating it within a gradient-based TO framework becomes even more cumbersome,” the researchers explained in the paper. “Therefore, in this research, a physics based yet highly simplified approach is proposed in order to identify zones of heat accumulation in a given design. The computational gain offered by the simplification, makes it feasible to integrate the heat accumulation detection scheme within a TO framework.”

Definition of overlapping cells for heat accumulation detection.

In addition to being used in a TO process, the team’s new procedure can also be used to independently analyze 3D printing designs, manual design improvements, and even determine the best build orientation.

Equivalence of a 3D body (A) to a simplified body (B) with equal thermal capacitance
and conductance.

Two simplifications made in this research can be used to help lower the computational cost that’s associated with the thermal analysis of 3D printable designs. The first, “motivated by the fact that the local geometry of only few previously molten layers” can significantly effect the new layer’s initial cooling rate, is to perform thermal analysis in the vicinity of the 3D printed layer being deposited.

The second is to use a steady, rather than transient, state thermal response to predict heat accumulation.

“For this purpose, a physics based conceptual understanding is developed which enables estimation of spatially averaged transient thermal behavior of a local geometry just from its steady state response,” the researchers wrote.

A structure’s topology can influence its internal heat flow; as such, different geometrical features in an AM design can obstruct or facilitate heat flow during the 3D printing process differently.

The researchers explained, “In this work we explore the possibility to approximately quantify, and hence compare, different geometries from the viewpoint of heat accumulation. For this purpose, first the concepts of thermal conductance and time constants are studied.”

Time constant maps obtained by the heat accumulation scheme using the concept of
overlapping cells.

Thermal conductance, equivalent to the reciprocal of thermal resistance, is a structure’s measure to conduct heat, while the time constant of the transient thermal response is studied to quantify the heating/cooling rate. The team also divided the design in their experiment into overlapping cells, so as to increase the possibility of detecting the heat accumulation zones.

High time constants were recorded close to overhang surfaces, and so the researchers discovered that heat accumulation for design features depends a lot on the nearby local geometry, and that “purely geometric design guidelines of prescribing a limiting overhang value might become insufficient for preventing problems associated with local heat accumulation.”

“The computational advantage offered by the proposed method enables development of a physics based topology optimization method which would be beneficial for designing precision AM components,” the researchers concluded. “Next step for this research is to combine the developed method with density based topology optimization by penalizing design features which are prone to heat accumulation during each iteration.”

Co-authors of the paper are Rajit Ranjan, Can Ayas, Matthijs Langelaar, and Fred van Keulen. The team will publish an additional paper on their heat accumulation detection method’s integration within a TO framework.

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New Study Shows that SLM 3D Printing Has High Potential for Fabricating Metallic Glass Components

Metallic glass, also known as amorphous metal, was first introduced in the early 1960s, and since then, it seems that everyone wants in on the action. The material is valued for its many exceptional properties, such as low stiffness, near-theoretical strength, high corrosion resistance, and large elastic strain limits. Bulk metallic glasses (BMG), which have characteristic specimen sizes in excess of 1 mm, have been explored successfully for for glass formers.

It’s not easy to produce metallic glasses with complex geometry, because the molten alloys must be cooled rapidly to move past the nucleation and growth of crystals, and most commonly used methods, such as melt spinning, casting, and powder metallurgy, are limited in both complex geometry and dimension. That’s why it’s so important to continue exploring and developing more novel processing routes for producing amorphous components.

A schematic illustration of SLM-YZ250 3D printer: (a) operating mode of the device; (b) processing scanning pattern.

A team of researchers from the University of Science and Technology Beijing have been investigating the use of selective laser melting (SLM, also called DMLS, Direct Metal Laser Sintering, Powder Bed Fusion, Laser Powder Bed Fusion) 3D printing to fabricate Fe-based metallic glass powder with unrestricted, complex geometry. This specific technology offers very high cooling rates, which is important for glass formation of most BMGs, and can apply various processing parameters involving laser energy density to melt the metal powder.

The researchers recently published a paper, titled “Fabrication and characterization of Fe-based metallic glasses by Selective Laser Melting,” in the Optics and Laser Technology journal. The paper details SLM’s high potential for 3D printing metallic glass components with complex geometries.

The abstract reads, “Fe-based metallic glasses (MGs) can be potential structural materials owing to an exceptional combination of strength, corrosion and wear resistance properties. However, many traditional methods are difficult to fabricate Fe-based MGs with complex geometry. In this study, a new metallurgical processing technology, selective laser melting (SLM), was employed to fabricate Fe-Cr-Mo-W-Mn-C-Si-B metallic glasses. The microstructure, thermal stability and mechanical properties of the as-fabricate samples processing with different laser energy density have been investigated by X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and nano-hardness. Thanks to the high cooling rates of SLM, the crystalline phases in the gas-atomized powder almost completely disappeared and nearly fully amorphous structure parts were obtained after SLM processing. By choosing appropriate parameters, the size and quantity of the pores were reduced effectively and the relative density of the samples can reach values of over 96%. Although additional work is required to remove the residual porosity and avoid the formation of cracks during processing, the present results contribute to the development of Fe-based bulk metallic glasses parts with complex geometry via the SLM.”

(a) SEM secondary electron image of the gas-atomized powder; (b) SEM back-scattered image of the cross-section of the powder.

Fe-based BMGs are important for their unique combination of high physical, chemical, and mechanical properties, low affinity towards oxygen, and the fact that the raw material is less expensive than other commercial BMGs. So the researchers used a Fe-based metallic system Fe-Cr-Mn-Mo-W-B-C-Si with large glass forming ability (GFA) for the study, and used X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) to investigate structural variations between the original powder and the SLM 3D printer parts.

Samples prepared with different laser energy density.

According to the powder’s morphology, the surfaces are very smooth, which results in good flowability. But, the team also observed that micro-pores were formed by trapped glass, and that crystallization did occur in a small amount of the powder, due to the fact that, as the researchers explained, “the cooling rate during gas atomization is not high enough to suppress crystallization.”

However, the crystalline phases in the gas-atomized powder disappeared after SLM 3D printing.

Samples were 3D printed with different laser energy densities, in order to investigate the metallic glasses’ mechanical properties and microstructural evolution. By choosing the appropriate parameters, the researchers were able to successfully 3D print high quality Fe-based metallic glasses.

“At present it is great challenge to produce large-scale glassy alloys in sophisticated geometries with the existing technologies. SLM technology, including heating the powder to melting in very short time and then the melting pool rapidly solidifying procedures, provides new opportunities for the creation of large, geometry freedom of metallic glass components,” the researchers explained. “From the results above, we noticed that although the as-received powder had partially crystallized, the powder experienced a quickly laser processing procedure with high cooling rates, leading to nearly fully amorphous structure. This phenomenon proves that under optimized SLM processing conditions, the nucleation and crystallization are inhibited, and amorphous structure can be acquired.”

They also noted that to improve the quality of the SLM 3D printed parts by decreasing micro-cracks and pores, further fine-tuning of the processing parameters is necessary.

A selection of the as-built parts.

The researchers concluded, “In addition, the preparation process of the powder system still needs to be optimized, and ensuring a fully amorphous structure powders can be obtained which eliminates crystallization in the SLM parts. The present results confirm that additive manufacturing by SLM represents an alternative processing method for the preparation of bulk metallic glass components without limitations in size and intricacy. The processing method and conditions are in principle available for a large variety of metallic glasses production.”

Co-authors of the paper include X.D. Nong, X.L. Zhou, and Y.X. Ren with the university’s State Key Laboratory for Advanced Metals and Materials.

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Using Two-Stage T6 Heat Treatment to Tailor the Mechanical Properties of 3D Printed Aluminum AlSi10Mg Alloys

Backscattered electrons images to observe oxidation regions of (a) T6 heat-treated, and not in (b) as-built, selective laser melting samples, (c) magnification of (a).

While many aluminum alloy components are still fabricated using traditional casting technologies, there’s been plenty of research and development into 3D printed aluminum alloys as well. For metallic 3D printing, the selective laser melting (SLM) method is typically used to produce Al alloys; however, AlSi10Mg alloys made with SLM technology must set up different post-printing treatments. This is due to a rapid cooling rate during the solidification process, which causes the microstructure and mechanical properties of the part to be vastly different from conventional cast or forged metal alloys.

Additionally, high heat transfer, high reflectivity to the laser beam, and easy oxidation to a tenacious oxide film make SLM-produced AI alloys more difficult than those of steel or titanium.

A pair of researchers recently published a paper, titled “T6 heat-treated AISi10Mg alloys additive-manufactured by selective laser melting,” in the Procedia Manufacturing journal about tailoring the mechanical properties of SLM-fabricated AlSi10Mg alloys with a two-stage T6 heat treatment.

The abstract reads, “A two-stage T6 heat treatment has been proposed to tailor mechanical properties of the selective laser melting fabricated AlSi10Mg alloy. The process included solid solution at 535 ºC and artificial aging at 158 ºC for 10 h. The densification, hardness and oxidation behavior have been investigated after T6 heat treatment. The results demonstrate that the hardness of the T6 heat-treated samples are lower than untreated ones. This is because a fine-grained recrystallization microstructure develops during solid solution. Oxides aggregation and dimple distribution occurred due to sufficient diffusion at the artificial aging of the second stage.”

Optical microscopy images of (a) as-built selective laser melting, and (b) magnification; (c) T6 heat-treated, and (d) magnification, samples perpendicular to building direction of selective laser melting.

The T6 heat treatment is most often used to increase the strength of Al-Si components with Cu and/or Mg in conventional manufacturing, which uses a high-temperature solution treatment to both dissolve larger intermetallic particles and homogenize the alloying elements. Then, lower temperature artificial aging is used to form fine precipitates.

New studies show that T6 heat treatment can actually cause cast alloys to soften, instead of harden, when they’re annealed at either 300 ºC or 530 ºC, which contrasts earlier research. In addition, SLM-fabricated AlSi12 post-solution had a 25% increase of ductility.

“However, most research so far focuses on how to increase the tensile strength during selective laser melting processing, only a few can refer to balancing plasticity and the resistance to facture by post heat treatment. Furthermore, only limited comprehensive work has currently been done to study heat treatment processes specific for selective laser melting-fabricated AlSi10Mg alloys, particularly on their influence on the mechanical properties,” the researchers wrote. “Thus, this raises the need to verify conventional T6 heat treatments when it comes to selective laser melting materials, and what would be the influence of these heat treatments on the specific mechanical properties of selective laser melting-produced AlSi10Mg alloys.”

Hardness measurement of as-built selective laser melting and T6 heat-treated samples.

The paper’s proposed thermal treatment uses a solid solution at 535 ºC and artificial aging at 158 ºC for 10 hours on gas-atomized AlSi10Mg powder provided by Renishaw. Then, the researchers investigated the impact of their two-stage T6 heat treatment on both the mechanical and microstructural properties developed in SLM 3D printed samples.

The samples’ mechanical properties depend on the densification mechanism of the parts, and their microstructure during SLM processing.

“In AlSi10Mg alloys, the theoretical bulk density usually is 2.68 g/cm3. After the selective laser melting processing, the densification of the as-built samples was 96%. By contrast, after T6 heat treatment, the mean value of the densification of the samples is 96.52% and the maximum densification is 98.13%,” the researchers wrote.

These similar values are an indication that the two-stage T6 heat treatment had very little effect on the SLM 3D printed parts’ densification. Additionally, post-T6 heat treatment, the hardness of the as-fabricated sample in a building direction significantly decreased as well. Evidence also shows that the T6 heat treatment can spheroidize oxidation regions to even further enhance the mechanical properties of SLM 3D printed samples.

The researchers concluded, “This heat treatment aims to tune the mechanical behavior of selective laser melting-produced AlSi10Mg alloys. The effects of the T6-like heat treatment on the densification, hardness, and oxidation behavior have been investigated. Similar densification of 96% in the as-built samples and of 96.52% in the heattreated samples indicates that the T6 heat treatment has no importance to the densification. Decrease by about 20% in the hardness of heat-treated samples compared with the selective laser melting as-built samples. The T6 heat treatment can spheroidize oxidation regions and thereby form dimple structure. This finding can offer an intriguing insight into explore oxidation behavior and mechanical properties of selective laser melting-fabricated AlSi10Mg alloy using a two-stage heat treatment.”

Co-authors of the paper are Xianglong Yu with the CAS Key Laboratory of Mechanical Behavior and Design of Materials (LMBD) at the University of Science and Technology of China and Lianfeng Wang with Shanghai Aerospace Equipment Manufacturer.

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