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Pushing the boundaries of additive manufacturing

Additive manufacturing

Matthew Dale details some of the key innovations seen at Formnext 2022

For me, attending Formnext 2022 helped cement a message shared by additive manufacturing (AM) experts in the weeks prior to the show – that AM systems are now very capable of delivering the precision, repeatability, throughput, part size and consistency demands of serial production. Gone are the days where this technology was simply viewed as a novel prototyping tool.

An overwhelming theme that came across this year was just how big additively manufactured parts are getting, with dimensions up to a metre and beyond now being well within reach.

For example, SLM Solutions recently extended the build envelope of its NXG XII 600 powder bed fusion system by 900mm in the z-axis – now totalling 600 x 600 x 1,500mm.

This newly released ‘NXG XII 600E’ model is designed for customers demanding larger metal parts at exceptional build rates.

Equipped with the same suite of twelve 1kW lasers as its predecessor, the new model delivers build rates up to 1,000cm3/hr – five-times faster than a quad-laser system and twenty-times faster than a single-laser system. With such speeds, serial production of complex geometries can now be completed in a matter of hours or days, rather than weeks and months. At Formnext the firm showed examples of large-scale parts built using the original NXG XII 600, including an impeller and an engine midframe made from IN718, and heat exchangers made from AlSi10Mg. The system can also work with other commonly qualified materials such as TiAl6V4 and various copper alloys.

Left and centre: SLM Solution's new NXG XII 600E is designed to build exceptionally large parts with build rates up to 1,000cm3. Right: An impellar produced on the NXG XII 600 in 5.5 days from IN718 with a layer thickness of 60µm

SLM has already accepted its first order for the extended system from Concurrent Technologies Corporation (CTC), the prime contractor for a US Air Force Research Laboratory (AFRL) project, which intends to additively manufacture components that can withstand the extreme temperature and performance requirements of the space and defence sectors. 

“The reason why we came out with the original NXG XII 600 was because it was being strongly requested by our customer base,” Emily DeSimone, Director of Global Marketing at SLM Solutions, told Laser Systems Europe at the show. “That system offered a 600 x 600 x 600mm build envelope, however we were getting feedback that an even larger format was required. So this is what the extended z-axis can now offer. CTC, which helped fund the development of the NXG XII 600E via an AFRL contract, will use the newly purchased system in its development of advanced hypersonic weapon systems once we deliver it in 2023.” SLM also had a range of other firms expressing interest in the newly extended system at Formnext, DeSimone added.

Despite only just releasing the newly extended system, it looks like SLM Solutions already has its sights set on even larger build envelopes. In the wake of the show, the firm announced its plans to increase build volume even further, with an upcoming solution set to be able to produce metal parts up to 3,000 x 1,200 x 1,200mm (LxWxH) at build rates up to 330cm³/h. The firm has not yet revealed when the new system can be expected, but claims it to be a ‘real revolution of manufacturing’ capable of producing ‘giant and massive’ metal parts.

Another example of large build volume was seen over on Prima Additive’s booth, where the firm’s new IANUS laser processing robotic cell was shown to be capable of producing parts up to 1,600 x 1,200 x 700mm in size via directed energy deposition (DED). 

Prima Additive’s new IANUS system is capable of producing parts up to 1,600 x 1,200 x 700mm in size via directed energy deposition

While configured for powder-based DED at Formnext, Daniele Grosso, Marketing Manager for the firm, informed Laser Systems Europe that the system can also be equipped with changeable heads to facilitate wire-based DED, remote laser welding and laser hardening. “It is capable of building a part using AM and then processing it using laser welding or hardening without having to remove the part from the build chamber,” he said.

The machine was developed in collaboration with Siemens, and so incorporates the firm’s expertise in robotics, automation and digitalisation. “The IANUS therefore presents a series of functional solutions for inclusion in the factory of the future,” Grosso continued. “This machine and its robotics therefore work with any CAD-CAM-CNC software also developed by Siemens. So in this way, if a manufacturer has traditionally used a milling machine equipped with Siemens software, they will be able to easily program the IANUS and its robotics without having to learn a new programming language. They will also be able to handle data surrounding the system and its processes in the same way they are used with other Siemens-powered systems.

Copper printing with green laser technology

Also on Prima Additive’s booth was evidence of another developing AM trend: the ability to print components from pure copper. The firm was demonstrating the exceptional quality and repeatability of its Print Green 150 system, which thanks to a 200W green laser can produce pure copper parts up to 150 x 160mm in size with densities exceeding 99.9%. The system can also be equipped with an infrared laser for processing standard alloys. This can be done in a dual-laser configuration to increase productivity – either featuring two green lasers, two infrared lasers, or one of each if manufacturers are required to build both copper and standard alloy parts. Each laser is equipped with a beam expander to adjust its beam size according to requirements. The system can achieve a single line width of 0.1mm and a minimum layer thickness of 0.02mm during builds in order to deliver high precision.

A range of copper parts can be printed with Trumpf’s new TruPrint 5000 Green Edition, including gas coolers, fluid mixers, semiconductor coolers, shaft inductors and heat exchangers

“It also has a dual pre-heating system that allows the surface of the powder bed to be heated both from above and below via a heated plate, thus allowing the powder bed to reach a temperature of up to 300°C, if required,” remarked Grosso. “In addition, a high-speed coaxial pyrometer monitors the temperature in real time while two cameras monitor the process and the powder bed. Lastly, the system also offers optimised gas flow in order to minimise nitrogen or argon consumption.”

Copper printing was also front and centre over at Trumpf’s booth, where the firm was showcasing a new version of its largest 3D printer, the TruPrint 5000. The system has been equipped with a TruDisk 1020 green laser in order to facilitate the processing of large copper components up to 300mm in diameter and 400mm in height. The system can deliver 800W of laser power to the workpiece to achieve build rates of up to 100cm3/h, with layer thicknesses down to 30μm. 

At the show, the firm displayed a radio frequency quadrupole manufactured from electrolytic tough pitch (ETP) copper, as well as other copper parts including gas coolers, fluid mixers, semiconductor coolers, shaft inductors and heat exchangers.

A radio frequency quadrupole manufactured on the TruPrint 5000 from electrolytic tough pitch (ETP) copper as part of the I.FAST Project.

Trumpf’s research into the gas flow and laser exposure strategies has enabled it to maximise the repeatability of the TruPrint 5000, allowing such components to be produced in series production across a network of machines. The firm claims it can even print copper “as easily as common 3D printing materials such as stainless steel”. The system can also be used for hybrid production, for example to print special functions such as cooling channels onto milled or cast components, or for repairing parts such as turbine blades.

A new approach to AM process monitoring 

In addition to optimised gas flows and laser exposure strategies, the increasing repeatability of AM systems can also be attributed to continual advances in process monitoring technologies. Arrays of visual-, thermographic- or OCT-based cameras and sensors are now being used in modern AM systems to reliably identify defects during builds. They even enable parameters to be adjusted on the fly to minimise the creation of such defects, ensuring maximum precision and consistency throughout builds.

While GF Machining Solutions has integrated such sensor technologies into its existing systems, this year at Formnext the firm was presenting a prototype electromagnetic system currently under development in collaboration with Swiss companies AMiquam SA and Inspire AG. 

The plug-and-play system is based on eddy current technology and was being shown on GF’s DMP Flex 350 laser powder bed fusion (LPBF) machine. It is designed to collect information on AM process stability via quality assessment on porosity or other defects, in compliance with the international standards and regulatory bodies of regulated markets such as aerospace and healthcare.

“There are a number of process monitoring technologies currently being applied to LPBF,” said Dogan Basic, Product Marketing Manager for Advanced Manufacturing at GF Machining Solutions. “For example, one of the main methods currently involves one or multiple visual-, thermographic- or OCT-based sensors being used in situ to examine the melt pool and identify defects. While these technologies do work, many aren’t currently being used across aerospace or medical device manufacturing to assess parts, as these technologies aren’t yet standardised or validated in these industries.”

He continued by explaining that for non-additively-manufactured parts, such industries often use eddy current technology for quality check and parts validation. This involves passing an electrical current through the parts in order to map them and reveal porosity and other defects.

GF Machining Solutions presented a prototype electromagnetic process monitoring system intended for heavily regulated industries 

“And so what we are doing here is working with our partners to adapt this technology to LPBF,” said Basic. “The appeal here is that this is already a standardised and validated technology used across heavily regulated industries. And so if this technology – which delivers results similar to melt pool monitoring techniques – is used to check a part, these industries will know not only whether a part is good or not, but also whether it is validated for use in their industry.” 

Currently such industries have to use non-destructive testing solutions such as CT-scanning to validate AM parts, which can be expensive. Therefore, according to Basic, by using a monitoring technology already validated by the official regulatory boards, firms in these industries will no longer have to resort to this kind of testing.

He explained that the current version of the DMP Flex 350 uses both a melt pool monitoring system as well as a camera to photograph parts after each build layer. However, the idea in the future is to offer as an option the new eddy current technology, the data of which will be fed into software that, according to Basic, is being beta tested over the coming months.

We anticipate this new offering to attract a lot of interest from aerospace companies due to it preventing the need to perform non-destructive testing,” he said. “We are currently collaborating with multiple large aerospace suppliers and OEMs to develop the new technology, and have so far received very positive feedback.”

Should the new technology continue proving successful, GF Machining Solutions plans to integrate it across its DMP Flex 350 Dual system as well as the rest of its AM system range in the future.

GE Additive’s Concept Laser M Line pushed to its limits

At GE Additive’s booth, the firm unveiled the results of a joint design and engineering project with Shell International – an additively manufactured oxygen hydrogen micromixer measuring 296mm in height and 484mm in diameter.

The complex, non-functional demonstration part was printed in nickel alloy 718 on a GE Additive Concept Laser M Line system, installed at Shell’s 3D Printing CoE and Workshop at its Energy Transition Campus Amsterdam (ETCA) in the Netherlands. Having its own printing capability grants Shell’s R&D department the freedom and speed to create novel parts not available in the market and solve new technical challenges in support of the ongoing transition to sustainable energy sources.

“We really wanted to put the M Line through its paces and test it to its limits,” said Joost Kroon, an additive technology subject matter expert at Shell. “Working with the GE Additive team we agreed to apply additive technology to reimagine a large, complex part, incorporating channels that would be difficult to manufacture conventionally. Working on an oxygen hydrogen micromixer aligns well with our companies’ strategies to play a positive role in the energy transition.”

Sonali Sonawane Thakker, a lead design engineer at GE Additive’s AddWorks team based in Munich, was tasked with researching, designing and iterating the final design on display at Formnext. Her mission was to design a part that was large and complex and incorporated channels for hydrogen and compressed oxygen. Sonawane Thakker was able to deploy the design freedoms that additive technology affords to rethink the structure and shape of the part.

An additively manufactured oxygen hydrogen micromixer was one of GE Additive’s centrepieces at Formnext

“Once we had settled on a part, our preliminary research showed that existing micromixers – also known as hydrogen-oxygen burners – are typically cylindrical, when conventionally manufactured, to accommodate the complex layout of tanks, pipes and nozzles,” she said. “For additional complexity we chose a large conical design and also moved from a flat to a curved structure with an ISO grid to increase the overall strength, rather than a customary flat one.”

Thakker sought inspiration from geometries and symmetry in the natural world, in particular the Fibonacci sequence replicated in flowers and petals. “With over 330 individual nozzles to incorporate in a circular pattern, I took inspiration from the ways pollen grains form in a flower head. The curved wall and the conical shape also reflect the shape of a petal,” she added.

Post processing was also completed at the Shell facility, and this was made easier through inclusion of powder removal holes, incorporated by Thakker during the design phase. The part was completed in early November and sent to GE Additive’s booth at formnext. 

“Given this is one of, if not the largest and most complex part built on an M Line so far, we’ve remained in close contact with the GE Additive team in Munich and were supported on the ground here in Amsterdam by their local field service engineers,” said Lisa Kieft-Lenders, team lead at at the Shell 3D Printing Center of Excellence and Workshop. “After some adaptions at the start, the build ran smoothly over nine days.”

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