Okay, so you’re struggling to tell the difference between types of 3D printers like FDM and SLA? Or SLS and EBM? Or LOB and MJF?
We hear your pain. With all these acronyms flying around, you’d be forgiven for mistaking a certain type of 3D printer technology for a genre of dance music.
Have no fear! Our very short guide explains the essential types of 3D printers currently out there. Have a blitz through this article and you’ll soon be able to tell which from which. And what from what.
We’ve also embedded some videos under each, to better illustrate the 3D printer technologies. Enjoy!
FDM is the most common 3D printing method used in desktop 3D printing. Thermoplastic filament is heated and extruded through an extrusion head that deposits the molten plastic in X and Y coordinates, while the build table lowers the object layer by layer in the Z direction.
Effectively, the object is built from the bottom up. If an object has overhanging parts, however, it will need support structures that can be removed after the printing is finished.
This type of 3D printers is a cost-effective means for product development and rapid prototyping in small business and education sectors since it’s capable of fabricating robust parts reliably and quickly.
SLA has the distinction of being the oldest of the 3D printing technologies, first invented by Chuck Hull in 1983.
SLA works by exposing a layer of photosensitive liquid resin to a UV-laser beam so that the resin hardens and becomes solid. Once the laser has swept a layer of resin in the desired pattern and it begins to harden, the model-building platform in the liquid tank of the printer steps down the thickness of a single layer, and the laser begins to form the next layer. Each layer is built on top of the preceding one.
Like the FDM 3D printer technology, objects with overhangs 3D printed with this type of 3D printer will require support structures. And after printing has completed, the object must be rinsed with a solvent. Sometimes it’s also baked in a UV oven to finish processing.
SLA creates smooth surfaced objects with extreme detail, and it’s increasingly popular in industries like jewelry and cosmetic dentistry for creating castable molds.
Continuous Liquid Interface Production (CLIP) could be the next big thing in SLA 3D printing. This 3D printing technology also uses resin and an ultraviolet beam. The difference lies in an oxygen-permeable membrane that lies below the resin, which makes the process much faster. The inventors claim they can create objects up to 100 times faster. The first CLIP 3D printers already are in a test phase.
Digital Light Processing (DLP) and Stereolithography have a lot in common. Both types of 3D printers use liquid photopolymers. You might have heard of these “resins”. DLP and SLA printers cure them by applying light to it. SLA does that with a laser, DLP with a special projector.
DLP technology was invented in 1987 by Larry Hornbeck of Texas Instrument and became extremely popular in projectors. DLP uses a computer-controlled, micro-mirror grid, laid out on a semiconductor chip. These tiny mirrors tilt back and forth. When a mirror is tilted, it reflects light, creating a bright pixel. When the mirror is tilted the other way, the pixel is dark. The technology is used in movie projectors, cell phones, and also for 3D printing. One of the benefits for 3D printing is its speed: You can print layers in an instant with this type of 3D printer.
DLP 3D printers are mainly used in professional environments. This type of 3D printer delivers robust pieces with excellent resolution. But also makers and hobbyists are building their own 3D printers with it. They use used beamers or even smartphones to cure the resin.
SLS is similar to SLA, but the key difference is that this type of 3D printer uses powdered material in the build area instead of liquid resin. A laser is used to selectively sinter a layer of granules, which binds the material together to create a solid structure. When the object is fully formed, it’s left to cool in the machine before being removed.
SLS is widely used for product development and rapid prototyping in a wide range of commercial industries, and also for limited-run manufacturing of end-use parts. The materials used in SLS can range from nylon, glass, and ceramics to aluminum, silver, and even steel.
This type of 3D printer requires the use of expensive high-powered lasers, however, which puts it a bit beyond the reach of the average consumer — with the exception of professional 3D printing services like Shapeways, Sculpteo, and i.materialise.
SLM is sometimes regarded as a subcategory of the SLS 3D printer type, where SLM uses a high-powered laser beam to fully melt metallic powders into solid three-dimensional parts.
Typical materials used are stainless steel, aluminum, titanium, and cobalt chrome. For applications in the aerospace or medical orthopedics industry, SLM is used to create parts with complex geometries and thin-walled structures, with hidden channels or voids. Elsewhere, as in the video above, it’s been used to fabricate gas turbines for the energy industry.
In contrast to SLM, the EBM technique uses a computer-controlled electron beam under high vacuum to fully melt the metallic powder at high temperatures up to 1000 °C.
This type of 3D printer can use metals like pure titanium, Inconel718, and Inconel625 to fabricate aerospace parts and medical implants. But while the 3D printer technology is exciting, it’s currently very slow and very expensive.
LOM uses layers of adhesive-coated paper, plastic or metal laminates, which are fused under heat and pressure and shaped by cutting with a computer controlled laser or knife. This is sometimes followed by machining and drilling. The 3D object is created layer-by-layer, and after the excess material is cut away, the object can be sanded or sealed with paint.
Though the dimensional accuracy of this 3D printer type is slightly less than SLA or SLS, LOM is one of the most affordable and fastest 3D printing methods available to create relatively large parts. It also allows for full-color 3D printed objects.
This type of 3D printing was invented at MIT. The 3D printing technology comes in many names. It’s known as “powder bed printing”, “inkjet 3D printing”,”drop-on-powder printing” or – probably most common – as “binder jetting”.
Binder Jetting is an additive manufacturing process. This type of 3D printer uses two materials: a powder based (often gypsum) material and a bonding agent. The agent acts as an adhesive between powder layers. Usually, the binder is extruded in liquid form from a printhead – just think of a regular inkjet 2D printer. After a layer is finished, the build plate is lowered and the process repeated.
You can use this 3D printing technology with ceramic, metal, sand or plastic materials.
These type of 3D printers have a huge advantage. You can print in full-color by adding pigments to the binder (usually cyan, magenta, yellow, black and white). This made it the preferred method for the popular 3D selfies. The drawback of this 3D printing method is the structural integrity of the objects. You won’t get high-resolution and rugged prints with this type of 3D printer technology – but there are some exceptions.
There’s also advancement in this type of 3D printing technology. In 2016, Hewlett-Packard introduced “Multijet Fusion” (MJF), which wants to bring Binder Jetting to the next level-
First, a layer of 3D printable material is deployed by a carriage. A second carriage with a thermal inkjet array passes from right-to-left, depositing a pair of chemical agents across the full working area. One is a fusing agent, to create a solid layer from the material, and the other is a detailing agent, to determine the physical outline of the layer being created. Finally, energy is applied to catalyze the fusing agent, and the powder imbued with the detailing agent remains inert.
Potential applications for this type of 3D printer are for rapid prototyping and short-run manufacturing in the automotive, medical and aerospace industries. However, the full extent of MJF capabilities is yet to be established, with newer fusing agents promising to offer different properties like full color, conductivity, strength, and thermal reactivity.
The Material Jetting technology is better known as”wax casting”. There‘s no inventor per se – it’s a technique used by jewelers since centuries. Lost wax casting (or investment casting) is a production process that mainly allows you to produce customizable jewelry of very high quality in various metals. But with 3D printing, there’s finally a process to automate wax casting – and for most jewelers, that’ quite something.
So it has become the dominant type of 3D printing technology if you’re a jeweler or want to experiment with casts.
There are a handful of professional wax 3D printers on the market, like the “Wax Jet” from Statasys. If you want to experiment with this 3D printing technology, you don’t have to buy a printer. There are 3D printing services like Shapeways or Sculpteo which use Material Jetting or Multijet Modeling (MJM) machines for this task.
Molten wax is deposited onto an aluminum build platform in layers using several nozzles that sweep across the build area. As the heated material jets onto the build plate, it solidifies. A different type of wax with a lower melting temperature is deposited below overhangs in your product, acting as a support material. When printing is finished, they are put in a heated bath that melts away support material.
Castable wax is very fragile and should be handled carefully. It will begin softening around 60C or 140F and melts at 80C or 176F. It can slowly deform and weaken over time, so better be fast.
If you want to experiment with wax casting on a regular FDM printer, you should give the Moldlay filament a try.
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