New to additive manufacturing and the key technologies that make it happen? Here’s everything you need to know to get started.
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Although it’s not a new technology in the strictest sense, additive manufacturing (AM) — sometimes referred to as 3D printing — has attracted significant attention in recent years for several reasons:
- Whether an organization is using AM systems and materials to shape new polymer blends or various aluminum alloys, it’s able to create parts according to geometric parameters that were once impossible or (at the very least) extremely difficult to achieve.
- Parts made through additive manufacturing can be smaller, lighter or require fewer individual components than those made using traditional processes while still matching or even exceeding the traditionally made part’s performance.
- Additive manufacturing has many applications, ranging from the casual and fun (running shoes and hockey helmets), to the exciting (rocket engines), to life-saving (medical implants and surgical equipment).
- Additive manufacturing users have seen tangible increases over time in production quality and efficiency, alongside reductions in time-to-market and overall expenses.
These are the broad strokes, but if you want to learn more about the background, processes, applications and successes of this remarkable technology, keep reading.
A Brief History of Additive Manufacturing
In some sources, you’ll see a patent filed by American engineer and inventor Bill Masters — specifically U.S. 4665492A, dated July 2, 1984 — called the first 3D printing patent. Others award this distinction to a patent filed by Charles Hull that same year. In fact, both are crucial to the technology’s history.
But a patent application filed with the Japan Patent Office (JPO) by Hideo Kodama (JP S56-144478) predates Masters and Hull by almost three years. Like the application Masters eventually sent to the U.S. Patent and Trademark Office (USPTO), it describes an automated process for creating 3D shapes by using heat — either laser or ultraviolet (UV) — to harden soft plastics.
Kodama couldn’t attract funding for his idea, despite publishing it in well-known trade journals, so he abandoned his patent application. Masters went through with his patent, received a grant and worked in the field for about 10 years but also attracted little attention.
An Important Year for 3D Printing
1984 marked the invention of several pivotal AM processes — though it took time for these early innovations to be realized at scale. Masters’ design (like Kodama’s) involved early examples of computer numerical control (CNC) and computer-aided design (CAD) programming integral to future AM systems.
This year also saw two patent filings vital to one of the first additive manufacturing processes with potential commercial viability: stereolithography (SLA).
The first, by French inventors Alain le Méhauté, Olivier de Witte and Jean Claude André, was abandoned by their sponsor soon after its filing. The second, belonging to Charles Hull, led to the production of the SLA-1 3D printer. The SLA-1 was prohibitively expensive for many, and Hull, like other early AM advocates, had trouble convincing traditional manufacturers of its potential. However, Hull also invented STL for the SLA-1’s design files, and that format remains common today.
Refinement and Upscaling
Engineers spent the 1990s steadily improving early additive manufacturing processes — SLA and fused deposition modeling (FDM) — as well as developing new ones. Most (though not all) focused on shaping polymers into 3D components, including material and binder jetting, sheet lamination, laser powder bed fusion (LPBF) and selective laser sintering (SLS). Some of these, like SLS and LPBF, allowed for some advanced metalworking, but the development of material deposition methods including microcasting and thermal spray truly paved the way for metal additive manufacturing.
Coupled with advancements in CAD software and the rise of powdered polymers and metals, the refinement of industrial 3D printing systems helped them become well-known for rapid prototyping throughout the 2000s. In the 2010s, additive manufacturing had scaled up enough to facilitate part assembly at much higher levels, approaching true mass production. Despite challenges with material compatibility (mostly on the metal side), the initial cost and efforts needed for implementation, a skills/knowledge gap and skepticism from traditional manufacturers, the technology’s presence and importance continue to expand.
The Major AM Technologies
While there are many more additive manufacturing methods than would fit in this article, making an informed decision about AM requires an understanding of the various technologies at play.
Vat Photopolymerization
Vat photopolymerization (or sometimes simply polymerization) is arguably the most common SLA process. This method’s name comes from the source of the material that fuels production: a vat of liquid photopolymer resin. A build platform is repeatedly lowered into (and then raised from) the vat, and every time it emerges, a UV or laser light source hardens the resin on the platform into layers that form a component according to the design parameters of the system’s connected CAD software. When assembly is complete, the system removes the product from the vat, which is drained of excess resin.
Objects additively manufactured through vat polymerization may need more post-processing than parts made through other AM methods. Further UV or laser exposure can be necessary to harden the component effectively. Also, during the build, support structures may be needed on the platform so the hardening resin forms the designer’s intended shape. These must later be carefully removed from the part. Overall, vat polymerization is a fast and accurate process, but because finished components are not necessarily degradation- or corrosion-resistant, it may be better for prototyping than producing market-ready parts.
Material and Binder Jetting
Material jetting is closer in nature to traditional printing than most other additive manufacturing methods, even though 3D printing is sometimes used as an overall synonym for AM. Nozzles emit liquefied material (usually polymer or wax; occasionally metal) as repetitive drops onto a build platform. UV light hardens the drops as they form layers in line with design parameters and take the planned object’s shape. Because material jetting is only compatible with a select few materials, its utility is limited. The method’s chief advantage is low waste, which is also helpful for rapid prototyping.
Binder jetting combines powder and liquid, depositing them in alternating layers, with the liquid — typically a polycarbonate or polyamide — functioning as an adhesive. The main advantage of this method is that powdered metal alloys can be used together with polymers or ceramics to create a part, but this is somewhat offset by the lengthy post-processing time required for the liquid layers to cool and form suitable bonds.
Material Extrusion
This generally refers to fused deposition modeling (FDM), one of the first additive manufacturing methods to see commercial success. It’s also the method best known to consumer users of desk-sized 3D printers. Polymer or plastic is drawn into the printer, heated and finally deposited in layers through a nozzle, which automatically adjusts throughout the process to meet design specifications.
Material extrusion via FDM can only print with polymer or plastic. Although an FDM industrial printer is compatible with ABS plastic, which can be the basis for sturdy parts, it’s slow and only moderately accurate when compared to other additive manufacturing processes. This is the main reason why companies producing FDM printers pivoted sharply to the consumer market.
Sheet Lamination
An additive manufacturing method exclusive to sheet metal and paper, sheet lamination has limited applications, but can be useful for high-speed, low-cost prototype fabrication.
The metal version of this process is called ultrasonic additive manufacturing (UAM), and involves the ultrasonic welding of metal sheets (usually aluminum, copper, stainless steel or titanium). By contrast, laminated object manufacturing (LOM) involves layering paper sheets with adhesive. Both are only suitable for creating part models. That said, UAM’s ability to use multiple metals may help designers and engineers simulate how additively manufactured metal parts made of copper, for example, might be compatible alongside other metals in specific industrial applications.
Directed Energy Deposition
As its name implies, directed energy deposition (DED) typically uses a nozzle mounted atop a highly flexible automated arm to deposit material in layers atop a build platform at the exact same time a heat source is focused on the substance. DED has a number of variations, and can thus use polymer, ceramic or metal, but its most common subcategory, electron beam melting (EBM) is exclusive to metal.
While impractical for part production, this method can be useful as an additive technique for component repair, due to the flexibility of its nozzle. However, using DED for high-speed repair comes at the cost of accuracy, and if accuracy is the priority, engineers must sacrifice speed.
Powder Bed Fusion
Some of the most common additive manufacturing techniques fall under the umbrella of powder bed fusion, including SLS, selective heat sintering (SHS), selective laser melting (SLM) and EBM. These methods’ shared element is a reliance on powdered polymers or metals: Powders are taken from a container below or next to the build platform (bed) and distributed in layers with a roller or blade and then heated to solidify.
Here are some key differences between the various powder bed fusion methods:
- SLS fuses (sinters) polymers or plastics into finished parts.
- Direct metal laser solidification (DMLS) is the SLS variation used for powdered metals.
- SHS uses a thermal print head to sinter the layers in the powder bed together.
- EBM only works with metal powders under vacuum conditions, which allow the electron beam to fuse the layers in the powder bed.
Powder bed fusion is somewhat slower than other additive manufacturing methods and requires significant power usage. However, the laser-based variants of this technique are also arguably more capable of reliably producing functional, market-ready parts as opposed to models or prototypes.
EOS’ Contributions to AM Technologies
Industrial 3D printing systems available from EOS use the SLS and DMLS variations of powder bed fusion for polymer and metal powders, respectively. In fact, EOS not only helped popularize SLS for industrial applications, but specifically invented DMLS for metal 3D printing almost 30 years ago.
EOS takes a holistic approach to additive manufacturing and offers services to support it alongside hardware and software, including project consulting from the Additive Minds team and 3D printing courses to help additive novices become designers and refine engineers’ skills into expertise.
Contact an Additive Minds expert to learn more, no matter where you are on your journey into the world of additive manufacturing.
