This article is a complete beginner’s guide to 3D printing. We discuss every type of additive manufacturing, including its origins, and we talk about where this popular tech could go in the future.
3D printing is a method of constructing physical objects from digital models by adding or modifying materials layer by layer.
If you imagine this bottom-up, layer-by-layer process in your mind, you might be able to understand why it is synonymous with the term additive manufacturing.
It’s a huge boon to business, and 47% of the businesses surveyed by Forbes said they saw greater ROI on their 3D printing projects in 2017 than 2016. Additive manufacturing is future tech.
Read More: How Close are we to 3D Printing Bodies?
The GIF below should give you a good idea of the process.
However, keep in mind that some additive manufacturing doesn’t add materials at all. The first patented 3D printer ever is one example. These printers simply add energy to a volume of excess material.
A Brief History of Additive Manufacturing
Additive manufacturing is relatively new, and the true meaning of the term can refer to a few different things. The more practical term, 3D printing, describes the same concept.
The earliest 3D printers were built to shorten the time between design and prototyping. These processes were referred to as RP or rapid prototyping technologies.
Most of the time, when people refer to their 3D printer, they’re talking about a desktop, small-scale printer that usually just works with plastics. That’s essentially the same thing 3D printers were doing back in the late 1980s.
Nowadays, additive manufacturing has kicked it up a notch. In this guide, you’ll learn about the fusing of metal powder and even titanium wire to create industrial-grade machine parts. As you may know, even Boeing is using 3D printed parts in their commercial aircraft.
The first patent application for additive manufacturing was submitted in Japan, 1980, by one Dr. Kodama. Despite being a patent lawyer, Dr. Kodama never filed a full specification of the additive manufacturing process he wanted to patent. It was never granted.
Instead, Charles Hull won the first-ever additive manufacturing patent in 1986 for his SLA or stereolithography apparatus. First invented by Hull in 1983, the SLA was the first practical 3D printer and the first major type of additive manufacturing that we’ll cover.
Back then, Hull was working with a company that used UV light to add thin plastic veneers to furniture. Hull realized he could repeat this process independently to build a 3D object with thin, 2D-material layers.
Hull’s SLA was revolutionary. However, this UV-powered, liquid resin depositing printer now works in a crowded field. A number of 3D printers that use vastly different energy sources, base materials, and application methods joined the scene.
10 Types of 3D Printers:
- Stereolithography Apparatus (SLA)
- Selective Laser Sintering (SLS)
- Fused Deposition Modeling (FDM)
- Digital Light Processing (DLP)
- Laminated Object manufacturing (LOM)
- Selective Laser Melting (SLM)
- Electron Beam Melting (EBM)
- Binder Jetting (BJ)
- Material Jetting (MJ) Polyjet and Wax Casting Technology
- Rapid Plasma Deposition (RPD)
1. Stereolithography Apparatus (SLA)
As we discussed, this is the first ever patented 3D printer created by Charles Hull in 1986. Hull co-founded 3D Systems Corporation. In addition to Hull’s SLA, 3D Systems acquired licensing for Carl Deckard’s Selective Laser Sintering in the late 1980s. You’ll read more about that soon.
For the most part, SLA is known as a rapid prototyping process. SLA machines work with thermoplastic polymers that are typically used to create small-scale prototypes.
As the first 3D printer to be patented, additive manufacturing evolved with the SLA in mind.
Production Process: 3D CAD data (split into layers) directs the SLA printer’s scanning laser. The laser hardens liquid photopolymer (plastic) contained in the resin tank. Using UV light, the scanning laser uses X and Y axis mirrors to harden one layer of the object at a time.
After each layer, a recoater blade spreads liquid resin evenly onto the finished layer of hardened polymer. The hardened layer is submerged in the resin tank, the top layer is hardened, and the process repeats until the 3D object is completed.
Once the object is printed, a chemical bath is necessary to remove excess resin. Most SLA-printed objects are also commonly cured in a UV oven to “temper” the polymer and make it stronger.
Material(s) used: Liquid photopolymers
Printing Times: Desktop SLA prints @ .3-.7 in/hr
Key Benefits: Cheap materials, relatively fast print times, and many different SLA machines (from as low as $300) to choose from.
Watch Form Labs’ video below for a stereolithography demonstration on their Form 1+ 3D printer.
2. Selective Laser Sintering (SLS)
In 1987, Carl Deckard of the University of Texas filed a patent application for the Selective Laser Sintering (SLS) additive manufacturing process. Granted in 1989, the SLS patent was first licensed to DTM Inc. before being acquired by the 3D Systems Corporation.
Production Process: In SLS, high-powered CO2 lasers fuse powder materials resting on a scaffold, layer by layer. Just like an SLA printer, the platform on which the object in print rests moves downward and the object is printed from the bottom up. Once finished, excess powder is removed manually.
Material(s) Used: Powderized Nylon 11, Nylon 12, and PEEK (polyether ether ketone thermoplastic polymer) materials
Printing Times: Commercial SLS prints @ 1.9-2.7 in/hr.
Key Benefits: Produces lightweight, durable, and heat and chemical resistant production parts such as gas tanks. Faster than SLA. A good quality professional SLS printer starts in the $7,000 range.
Solid Concepts demonstrates the SLS process in their YouTube video below:
3. Fused Deposition Modeling (FDM)
Originally created by Scott Crump in 1989 and then made a proprietary additive manufacturing process of Stratasys Inc., FDM is an extrusion-based 3D printing methodology that many subsequent evolutions of AM technology have built upon. Freeform Fabrication (FFF) is a simplified interpretation of the process that entry-level manufacturers designed to avoid patents held by Stratasys.
This hasn’t stopped Stratasys from filing infringement lawsuits against FFF manufacturers, however.
Production Process: A thermoplastic filament is deposited, layer by layer, through a heated extruder onto the printing platform. The extruder works according to the 3D CAD data provided to the FDM machine. Once deposited, each layer hardens and bonds to the preceding layer.
Supporting scaffolding must be manually removed.
Material(s) Used: Thermoplastic polymers.
Printing Times: Standard commercial FDM prints @ .3-1.7 in/hr.
Key Benefits: FDM printers can print more complex geometric shapes and higher-quality industrial production parts quickly and reliably. Thermoplastic materials are environmentally stable and able to be fully recycled. Far greater waste than what is associated with SLA and SLS additive manufacturing processes.
Solid Concepts also has a demonstration of the FDM additive manufacturing process on YouTube:
4. Digital Light Processing (DLP)
Widely used for rapid prototyping purposes, DLP additive manufacturing is a useful, less-wasteful alternative to SLA printers. It was created in 1987 by then-Texas-Instruments-engineer Larry Hornbeck.
Production Process: Like with SLA, DLP 3D printers use light to solidify liquid photopolymers. Using more traditional lighting source like an arc lamp with an LCD panel or a DMD. Light is applied to one entire layer of the vat of polymer resin rather than following the pass of a laser.
Material(s) Used: Photopolymers.
Printing Times: Similar printing speeds to SLA printers but quicker at dense prints.
Key Benefits: $500-$5000+Less waste than SLA due to use of only a “shadow vat” of resin. One of the less expensive desktop 3D printers ().
Below is a demonstration of an intriguing, custom-built DLP printer by William Abbe.
5. Laminated Object Manufacturing (LOM)
Originally patented by Michael Feygin, Laminated Object Manufacturing is a 3D printing production method introduced by California company Helisys Inc. Using plastic and paper as basic materials, LOM is primarily a rapid prototyping form of additive manufacturing.
Production Process: LOM works by pressure-fusing or laminating paper or plastic layers. After layers are added, a laser or blade cuts away excess material according to 3D data. As each layer is cut away, a new layer of material is fused or laminated over the top of the completed layer. This process is repeated until the object is completed.
Material(s) Used: Thermoplastics and paper.
Printing Times: The McorArke (not solely a LOM printer) from the video below is said to be able to print @ .5 in/hr.
Key Benefits: LOM is an relatively low-cost, rapid 3D printer that uses cheap materials.
6. Selective Laser Melting (SLM)
SLM was first developed by the Fraunhofer Institute ILT in 1995, in Aachen, Germany. In 2000, MCP Technologies announced the development of their own Selective Laser Melting (SLM) additive manufacturing technology. This method was developed around the same time as many other additive manufacturing technologies developed by and for industrial manufacturers.
Laser Melting additive manufacturing can utilize metal powder and, as a result, is very expensive.
Production Process: See Selective Laser Sintering (SLS). The SLM process is almost identical except that it fully melts the powder substances rather than just sintering them. This enables the use of metal powders.
Material(s) Used: Predominately powderized metals.
Printing Times: According to Element.com: “The time taken to produce a turbine blade using SLM Solutions’ 3D metal printing machines could be reduced to as little as four weeks, compared to 44 weeks using current technologies.”
Key Benefits: High-dollar industries like aerospace can use SLM to create lightweight, high-durability production parts.
Below, DMG MORI demonstrates SLM additive manufacturing on their LASERTEC 30 SLM powder bed machine.
7. Electron Beam Melting (EBM)
Another metal powder-bed-based additive manufacturing process created by and for industrial manufacturing processes, Electron Beam Melting (EBM) was founded and patented by Swedish company Arcam AB in 1997, and it continues to be their proprietary technology.
For a diagram and demonstration of EBM, watch the video below.
Production Process: Working similarly to the Selective Laser Melting (SLM) additive manufacturing process, EBM completely melts metal powders, fusing them together to create industrial-grade production parts. The main different between EBM and SLM is the energy source used to melt the powder, where EBM uses a high-powered electron beam in a vacuum environment, rather than a laser encased in inert gas.
Material(s) Used: Metal powders.
Printing Times: EBMs are slower than desktop 3D printers, but the scale of the materials used and products created are also much more expensive.
Key Benefits: Because parts are created in a vacuum, resulting objects have stress-relieved components with properties stronger than cast and similar to wrought material.
8. Binder Jetting (BJ)
Binder jetting was created in 1993 by Ely Sachs and Mike Cima at the Massachusetts Institute of Technology. In 1995, Z Corporation acquired the licensing for this additive manufacturing process. In 2012, Z Corporation was acquired by the 3D Systems Corporation.
Production Process: To begin, a coater spreads a thin layer of powder over the printer platform. An inkjet nozzle deposits binding agent according to 3D CAD data which bond powder particles. Each droplet is incredibly small allowing for high-resolution construction. Color ink can also be added via the inkjet nozzles. Once one layer is finished, the platforms moves down, the coater reapplies a thin layer of powder, and the inkjet nozzle again selective drops binder from above.
Post-printing, the object is coated in excess powder and allowed to cure. This increases the object’s strength before the excess powder is cleaned away.
Material(s) Used: two different materials for one print. First, a powder-based material like gypsum, and a bonding agent.
Printing Times: Exact times vary widely, but Binder Jetting does have the largest build volume of any 3D printer because of a lack of need for object supports.
Key Benefits: Large build volume. Also, BJ is particularly useful for rapid prototyping because of the available option to print objects in full color.
9. Material Jetting (MJ) and Wax Casting Technology
Similar to Binder Jetting additive manufacturing, Material Jetting (MJ) is also known as wax casting. Unlike the other types of 3D printers on this list, there is no clear inventor to credit for Material Jetting. Many MJ printers work with liquid photopolymers, which, as you may know, need exposure to UV light to be solidified and bonded.
Production Process: Once the 3D model (CAD file) is uploaded to the printer, it’s all systems go. Using 3D CAD data, MJ printers add heated material to the build platform in selective layers. Nozzles deliver the material, and once the heated material lands on the build it cools and solidifies, aided by UV light exposure.
A semi-liquid, gel-like material supports objects with more complex structures. These supports are easily removed post printing. Unlike many of the printers on this list, no further curing or treatment is needed.
Material(s) Used: Liquid photopolymers and other liquid materials.
Printing Times: Commercial models print @ .3-.5 in/hr.
Key Benefits: Material jetting can use a wide range of materials with high accuracy.
Below is a high-quality demonstration of the Material Jetting process.
10. Rapid Plasma Deposition (RPD)
A proprietary additive manufacturing technology of Norsk Titanium, Rapid Plasma Deposition (RPD) is the one 3D printer on this list we know little about. What we do know is that aerospace industry giants like Boeing and Airbus are using Norsk Titanium’s parts in their commercial aircraft.
Production Process: Exact details unknown. Titanium wire is melted in an inert, argon gas environment with little waste.
Material(s) Used: Titanium wire.
Printing Times: Unknown.
Key Benefits: This process apparently produces incredibly durable, low-machining parts for the aerospace industry. Norsk Titanium claims there is essentially zero waste to this process.
According to Norsk Titanium, “The result is significantly less machining, and ultimately, a 50%–75% improvement in buy-to-fly ratio compared with conventional manufacturing methods.“
Watch a demonstration of Norsk Titanium technology below.