Advancing metal 3D printing tech

Metal 3D printing has the potential to reshape the way metallic objects are manufactured and four companies – Desktop Metal, ExOne, Rapidia and Velo3D – are breaking new ground with their metal 3D printing technologies.

Showcased in a recent report by International Data Corp. (IDC), a global provider of technology and telecommunications market intelligence, these companies are pioneering 3D metal printing technologies with the potential to reduce costs while providing significantly greater quality and production speeds.

"The 3D metal printing market is seeing dynamic growth, and a key part of that growth is the development of new technologies and materials. These new products are creating new capabilities that enable a wider set of manufacturers to adopt 3D metal printing," said Tim Greene, 3D printing research director at IDC. "But it's not just adoption, the lower costs, better quality, and faster production are also allowing wider utilization within the companies that use 3D metal printers, up to and including the production of end-use parts."

The four companies profiled in the "IDC Innovators: 3D Metal Printers 2020" report are expected to impact the 3D metal printing market with their innovative technologies and groundbreaking business models.

• Desktop Metal is included in the report because of its Shop System, a new binder-jetting based 3D printer that is more productive and less expensive than powder-bed fusion 3D printers, that should enable digital transformation in job shops.

• ExOne is recognized for the combined launch of the X1 160 metal binder jetting system; its patented Triple ACT technology; and a new metal binder that will enable future binder jet 3D printing of premium metals such as Inconel 718 (a nickel-chromium alloy with other metals such as iron, niobium and molybdenum), titanium and aluminum.

• Rapidia is featured for its "office friendly" water-based 3D metal printing technology.

• Velo3D stands apart for the development of a unique process that enables the production of "impossible" geometries.

While each of these companies individually bring new ideas to 3D metal printing, together they are advancing this relatively new technology toward wider commercial adoption.

3D printing

In recent years, the use of 3D printers has become increasingly popular with commercially feasible prices, more ease of use and diverse market options. The average consumer can now explore this new technology with vigor.

In most minds, the term 3D printing still applies to polymer-based printers with several different technologies and methods having been developed involving plastics, epoxy resins and nylon, to name a few.

These 3D printers essentially work by extruding plastic or other such easily malleable materials through a tiny nozzle that then moves precisely under a pre-determined computer design.

One layer is printed at a time, with sometimes up to several thousands of layers, until the final three-dimensional product is finished. This is typically called fused depositional modeling (FDM).

When printing a desired object, a design is required to input into the 3D printer, these designs are often created with computer-aided design (CAD) software, a 3D scanner or by digital camera and photogrammetry software.

As errors can occur many fail-safes are built into CAD, making it the preferred method of design.

Now the same technology that was developed for polymer-based 3D printing is gaining wider use to "grow" objects made of metal.

Metal growing machines

Traditionally a process that involved some combination of casting, fabrication, stamping and machining, the age-old technology of metalworking has begun to take on a 21st century look over the past decade.

While the traditional metal removal methods continue to be the mainstay of metalworking, growing engine brackets and large nuts on a 3D printer rather than machining them is becoming increasingly popular.

With the possibility to fabricate a necessary tool in an isolated location or quickly repair broken machinery by printing the part rather than wait days or weeks for it, many industries around the world are beginning to see the advantages that 3D metal printing can provide.

At present, the most popular metal 3D printing process is a powder bed system with many names – direct metal laser sintering (DMLS), selective laser sintering (SLS) or selective laser melting (SLM).

No matter the moniker, this technique uses a laser to melt a 2D design onto a flattened bed of powder before a new layer is set on top with the process repeating until completion.

This method is slow and requires a careful design approach, but the successes far outweigh the drawbacks with parts being printed this way being strong and durable.

Another way to print 3D metal objects is directed energy deposition (DED) or laser metal deposition (LMD), a powder-fed system. It sends a highly concentrated metal powder stream through an extruder, which is immediately met with a laser at the surface of the part.

DED is a highly accurate metal 3D printing process, which can also be used to repair broken parts.

And lastly, metal binder jetting applies a liquid binding resin onto a powdered metal material. This method is fast, relatively cheap and can also be used to create large structures.

The drawback to this style lies in the end product, the resulting strength and density being nothing compared to the traditional method of metalworking.

Post-processing can be done to binder-jetted parts to make them stronger, but this has a cost of further time.

With 3D metal printing, there are several different metals and alloys which are manufactured and modelled using 3D metal printers.

Aluminum, steel, brass, copper, bronze, sterling silver, gold, platinum, and titanium to name the most common.

As most of these are more of the soft and malleable material, extrusion is not a difficult process. However, as the more rigid and durable materials come into play, clever engineering and designs are required to keep structural integrity of the metal.

Desktop Metal, ExOne, Rapidia and Velo3D are taking innovative approaches to build upon these strong foundational 3D printing technologies.

Next gen metal printers

Desktop Metal's newly coined Bound Metal Deposition (BMD) is an extrusion-based metal Additive Manufacturing (AM) process where components are constructed by the piping of a powder filled thermoplastic medium.

Bound metal rods-metal powder held together by a wax and polymer binding-are then heated and siphoned onto the build plate, shaping the part layer-by-layer.

While most similar to powder-fed systems, where Desktop Metal truly shines is with their Shop System, the world's first metal binder jetting system designed specifically for machine shops-enabling shops to easily produce parts with exceptional surface finish and resolution at scale.

This technology leverages the ability to deliver an office-friendly 3D printing solution. Not requiring the unwieldy laser or electron beam facilities that would make most companies balk.

ExOne has focused their efforts on binder jetting printing, providing a range of products that could allow in-house fabrication of parts quickly and affordably.

Much like their polymer-based relative, the advent of commercially viable and easy to use metal printers could become the next mainstream device for entrepreneur and corporation alike.

Unlike usual 3D printers, Rapidia has developed a water-based metal paste technology which removes the debinding process and allows for parts to move right to sintering.

Debinding removes the primary binding material from the molded component, commonly a type of wax to help glue the layers together during printing, before sintering.

The debound components are then sintered, which uses a high temperature furnace to remove any residual binder and fuse the metal particles together to create a durable result.

Without the need for debinding and sintering, Rapidia's incredibly unique method saves tens of hours of time while still producing solid results.

Velo3D has devised a method of metal 3D printing without the supports commonly needed for the process

Supports serve two purposes and are commonly seen in most metal 3D printed models – as anchors to keep a product from moving due to thermal distortion and to transfer heat.

Temporary support structures are an inconvenient necessity in DED and traditional powder bed fusion (PBF) and often require post-print machining operations.

VELO3D separates itself from existing powder bed fusion solutions with its unique ability to print low angles and overhangs down to zero degrees (horizontal), as well as large diameters and inner tubes up to 100mm without the need for supports.

This not only eliminates the need for post-processing, but it overcomes the "45-degree rule" – a boundary requiring supports at angles less than 45 degrees. This lack of a need for supports frees designers to truly build three-dimensionally.

These unique approaches to a growing industry can only continue to help it flourish and as this technology continues to grow and develop, other major industries in the world may yet see revolutionary changes-medical, mining, military, auto, and even aerospace could see new possibilities open up, if a necessary part was available with just the press of a button.