You may have heard the term 'metal 3D printing' being thrown around in recent years. Since its inception, the concept has proven its worth in the development of both prototypes and industrial end-use parts and is slowly making its way into regulated industries such as aerospace, medical, and defense.
The reality is that metal 3D printing is a very broad concept. There is no single additive manufacturing technology that metal 3D printing boils down to, rather a collection of sub-technologies that - you guessed it - print with metals. There are now a whole host of companies that base their entire business models on metal 3D printing, whether it be through manufacturing 3D printers, developing novel 3D printing alloys, or providing metal 3D printing services.
Powder bed fusion
Without a doubt, the most popular and widely adopted metal 3D printing process is powder bed fusion. PBF makes use of either a laser beam or an electron beam to melt metal powder in a powder bed, fusing consecutive layers on top of each other to build 3D parts. With companies such as EOS, Farsoon, and SLM Solutions pouring so many resources into R&D, PBF is one of the more advanced 3D printing technologies out there and has its uses in just about every industry that benefits from metal components.
Earlier this year, Ford Motor Company and EOS collaborated to combat alloy wheel theft through the development of unique 3D printed locking wheel nuts. which can not be loosened with standard tools. For context, locking wheel nuts are used to secure the wheels of a vehicle, which can be unscrewed with the key supplied with them. Third-party removal tools for these nuts have become more accessible as a result of cars being bought and sold without passing down the original components.
Unfortunately, alloy wheels have become a target for thieves as they can use these tools to loosen and remove a car’s wheels, which are sometimes valued at around $2600. By designing the nut and key in a personalized manner using 3D printing, Ford aimed to provide a system that can not be removed using standard equipment. The nut and key are designed as one piece, then 3D printed using acid and corrosion-resistant stainless steel on an EOS M 290 metal DMLS 3D printer.
Elsewhere, in the aviation sector, aerospace supplier Premium AEROTEC, together with GE Additive, very recently announced that it had reached a new productivity milestone in the series production of titanium parts via PBF. Just last year, the partners were able to qualify multi-laser titanium builds on a GE Additive Concept Laser M2 system, and have since been working on increasing the machine’s throughput.
The flagship system features two lasers and a build volume measuring 250 x 250 x 350mm, as well as a 3D optic with variable spot diameter. The current generation of the machine, series 5, was designed with regulated industries in mind and claims to deliver the accuracy, repeatability, and safety necessary to produce such parts. These parts include fuel nozzles, engine casing components, and a whole host of other functional prototypes.
Directed energy deposition
One of the other major metal 3D printing technologies is directed energy deposition. DED, although not as popular as PBF, is capable of producing highly dense parts at previously unseen throughputs, with some machines being able to print several kg of metal every hour. The process involves depositing powder or metal at the tip of a nozzle, where it intersects with either a laser, electron beam, or plasma arc that melts and fuses it to the plate below. DED is very commonly used to repair parts and add to already existing components. As such, it’s used heavily in MRO applications in the aerospace industry.
Optomec, a leader in DED 3D printing systems, recently received a $1M contract from the U.S. Air Force to deliver a high-volume DED machine to be used for the refurbishment of titanium turbine engine components. The U.S.-based company was tasked with manufacturing the machine, which is set to feature a range of state-of-the-art capabilities, including an automation system for batch processing, an oxygen-free controlled atmosphere, and an adaptive vision system. The machine will be installed at Tinker Air Force Base in Oklahoma City.
The automated additive repair system designed by Optomec will be able to process tens of thousands of repairs each year, initially focusing on tip refurbishment for the U.S. Air Force’s turbine blades. The company will also assist the Air Force in developing optimal process parameters for a range of target repairs - a prime application of the technology.
Metal 3D printing: from novelty to common-place
Metal 3D printing is here and it's here to stay. A couple of decades ago, the technology may very have been a gimmicky novelty, but it has since found its uses in advanced industries such as aerospace and automotive. The ability to produce high strength parts with excellent thermal and chemical properties is a very powerful tool, all wrapped up in the design freedom wrapper offered by 3D printing. While the technology is currently limited in its throughput, its effectiveness in functional prototyping is near-unmatched. The next ten years will undoubtedly yield a plethora of technological advancements that will put it on a more level playing field with conventional manufacturing.