Metal 3D Printing & Additive Manufacturing

From machining to MIM, metal parts buyers have a wide range of options for addressing their part-production challenges. The key in choosing from among them is to remember that each technology brings something different to the table, and every part has unique requirements.

Metal fabrication does not lack for depth as an industry. No fewer than 6 distinct—and commonly used—techniques exist for the manufacture of metal pieces and parts in 2018. Each can be considered the “best” option given certain conditions. For this reason, it’s often tough for an organization looking to outsource a specific production run of components to decide just which method is right for them. The list of options is long, and it’s growing more nuanced by the day.

Production runs of small, intricate metal components have traditionally been addressed by metal injection molding or investment casting. Some manufacturers, however, are finding that advances in 3D printing technology can make it a cheaper and faster alternative.

The question of which manufacturing method is best suited to metal part production can be complicated. It’s not a decision that can be reached by weighing only a single factor. To arrive at the best decision, it’s important for businesses to consider many factors and prioritize.

No matter how you slice it, the spike in industry-wide 3D printing revenues over the past 5 years has been impressive. A close look at that growth, however, reveals something interesting: it’s been disproportionately driven a small handful of vertical markets. Of these select markets, none has been as influential as MedTech. Metal-based additive manufacturing (AM), in particular, has proven to be perfectly suited to meet a number of needs in medical and dental device production.

Overview of Material Jetting in Metal 3D Printing

Material Jetting is relatively new and similar to binder jetting, with one key difference -- instead of a binder being jetted through the printhead, a metallic material is jetted. This material is jetted onto the build tray directly using either a continuous jetting or Drop on Demand (DOD) process. The jetted metal is deposited on the build tray in the cross section of the part for that layer. This process continues as it builds up layer after layer. The resulting part still needs to be sintered in a furnace to achieve final part density. Previously, material jetting was limited to plastics and polymers, but recent advances have seen new companies attempting to commercialize the process for metals. XJet currently shows the most promise for material jetting with its patented NanoParticle Jetting technology and recently shipped its first commercial machine to a customer.

Overview of Directed Energy Deposition in Metal AM

Directed Energy Deposition (DED) is an additive manufacturing process where metal wire or powder is combined with an energy source to deposit material onto a build tray or an existing part directly. Parts chosen for DED are typically large without the need for tight tolerances. DED methods are capable of building very large parts and are popular because of the rapid deposition speed. Because it closely resembles welding, DED is commonly used to repair and maintain existing parts. DED machines usually mount a nozzle on a multi-axis arm, which then deposits the metal feedstock to the surface. When used with 5 or 6 axis machines, the material can be deposited from nearly any angle and is melted upon deposition with a laser or electron beam. This process means DED can be used to build objects very quickly and is only limited in size by the reach of the robotic arm.

Overview of Metal Extrusion for 3D Printing

Metal extrusion in additive manufacturing is a fairly new process. Similar to the wildly popular plastic-based FDM process, filament is heated and drawn through a nozzle and then deposited layer-by-layer. This filament is a combination of thermoplastic material and metallic particles. The nozzle moves in the x and y axes across the part for a given layer. The build platform then lowers to make room for new layers. After the part is complete, it is placed into a sintering furnace to burn out the remaining plastic and sinter the metal particles together. Extrusion-based additive manufacturing has been widely used for plastics and polymers, but only recently has developed to create metal parts.

Overview of Binder Jetting

Binder Jetting is a powder bed process that utilizes inkjet technology and a binding agent. The liquid binder is used to “glue” the metal powder together within and between layers. A layer of metal powder is first rolled onto the build tray, and then an inkjet print head moves along the x and y axes and deposits binder in the shape of the part for each respective layer. After each layer is created, the build platform is lowered incrementally to make room for the next layer. The part being printed is supported within the powder bed by the unbound powder, which is then removed to complete the process. The result is a “green part” which then needs to be placed in a sintering furnace to achieve final part density.

Overview of Powder Bed Fusion - Metal 3D Printing

Powder Bed Fusion is a popular technique for metal additive manufacturing and includes two main technologies: Laser Sintering and Electron Beam. These techniques are grouped together since they each begin with a layer of metal powder being rolled onto the build tray, and then an energy source (laser or electron beam) fuses or melts the powder into deliberate 2D designs. These 2D layers are fused on top of each other to create the 3D object. Electron beams produce more energy than lasers and are chosen to fuse the highest temperature metal superalloys for parts used in extreme conditions such as jet engines and gas turbines.

In the firearms community, 3D printing is a topic of hot conversation. Firearms enthusiasts frequently pitch the benefits of additive manufacturing, which allows firms both large and small to rapidly prototype new components and pieces, and bring them to market faster. Hobbyists have been watching the pricing of AM equipment fall, some hoping that they can one day print complete firearms at home. As the saying goes, they want to "be able to produce AR-15s at home using 3D printers they paid for in Bitcoin..."

As the research from Dimension clearly demonstrates, most prospective 3D printing customers are waiting for big success stories prior to adopting the technology. The burden is on us, 3D printing companies, to showcase fantastic new applications of the technology.