Most people have heard about 3D printing, and they might have even considered buying one for their cousin on her birthday. But what exactly is it?

3D printers are a fascinating new manufacturing technology. They were originally invented to assist labs in creating prototypes of different tools and products they were developing. It provided a quick way to design, produce, and test items or prototypes in various fields: aeronautics, medicine, or cars. 

Once the patents ended for some of these technologies, businesses started marketing commercial versions. Any lab, workshop, or individual could now get their hands on this technology. This made a large manufacturing capacity accessible to anyone.

Today, there are hundreds of distinct models of 3D printers. As more people get their hands on the technology, different uses crop up, new patents are filed, and the technology expands in its function. There are even 3D pens!

What ​Is 3D printing?

3d printer

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Although we’ll see that there is a confusing variety of different printing processes, they all have some features in common.


A 3D printer is a computer-run device that layers specific materials into a solid, three-dimensional object. Each object is first designed digitally. Then, the design is handed over to the computer. From there, the process is automatic. 


3D printing is also known as additive manufacturing (AM). For a long time, 3D printers were meant only to design and produce prototypes. A prototype is simply a rough draft or sketch of a final product used for testing and proposals. Mass production of specific products was out of the question.


But 3D printers have become a desirable way to manufacture certain products. Not only does a 3D printer make manufacturing possible for your everyday person, but it also allows serious manufacturers to design and produce highly complex parts. Traditional metalworking and plastics aren’t capable of this level of complexity. 


3D printing is expected to have a big impact on the future of manufacturing and technology.


The History of 3D Printing

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As with many inventions throughout history, culture and society were primed to start inventing 3D printing. The availability of laser technologies, the demand for more customized prototypes and parts, and other factors, all led to this tech development.


In the early ‘80s, Japanese and French scientists were experimenting with resin-based 3D printing called thermoset polymers. These are most similar to Stereolithography and Digital Light Processing, which you will read about below.


An American named Chuck Hull filed the first patent for a 3D printing process. He developed Stereolithography, which became the first rapid prototyping system. Hull was pivotal in developing other features that would become essential for other types of 3D printing, particularly the super-small “digital slicing” of each object to be printed. 


From there, the technology spread, and distinct types were patented and marketed. 


So if you’re looking to get into 3D printers, deciding on which type is the best for your needs can be overwhelming. They vary in cost, materials, results, and capabilities. Where do you start? To help you navigate the complex world of 3D printing, let’s take a look at five types of 3D printers and their functions.

Material Extrusion Printers

plastic skull

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The most common printer on the market today are the ones that extrude some material through a nozzle. Extrude is an uncommon word that just means squeeze out. 


How It Works

With material extrusion printers, a plastic that can be melted and cooled again (known as a thermoplastic) is funneled through a nozzle. This material starts as a solid but is heated into a glue-like substance as it is squeezed out. The nozzle follows the design and creates extremely thin layers of material. 


As the layers cool, the material solidifies, and a three-dimensional object is produced. Because the structure may be lopsided or top-heavy, the design program includes temporary support structures that must be printed, as well. These are removed after the print is finished.


A single print can take many hours, sometimes even days. Compared to some of the other processes we will talk about, the material extruder printers are relatively slow. But by the time it’s done, you’ve got yourself a printed object!


Fused Deposition Modeling (FDM)

Most people who buy 3D printers end up buying a Fused Deposition Modeling (FDM), the most common material extrusion printer. These are also known as Fused Filament Fabrication (FFF) printers. This type of printer is most common because of its simple technique. 


These have become so common and affordable that they’ve been informally dubbed “desktop printers.” An example printer for sale: the child-friendly XYZ Printing Da Vinci Mini, which comes in at $259. For some printers, the type of “filament” or plastic used has to be bought from the maker of the printer.


What’s ​Its ​Function?

The inventor of the FDM, Stratasys, has a top-to-bottom manufacturing service to offer to businesses looking into 3D manufacturing. They make car parts for top of the line auto companies, construction tool makers, and even toys like LEGOS. 


But because of the simpler nature of these printers, hobbyists can make just about whatever they want with an FDM, as long as they have the design. So far, it’s the FDM printers that have made the biggest inroads into the market. They are paving the way to the future of additive manufacturing.

Vat Polymerization Printers

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The second type of additive manufacturing is vat polymerization. In this process, rather than simply heating a thermoplastic and squeezing it out onto the work surface like a tube of toothpaste, a laser is used with resin. Vat polymerization was the first kind of 3D printing patented. 


How It Works

In vat polymerization, light is used to make polymers react and solidify. So instead of layering thermoplastics through a nozzle like with an FDM, polymerization uses a speedy process of solidifying polymers through the use of both lasers and LED or UV lamps. 


There are two different types of printers that polymerize in a vat: stereolithographic (SLA), and digital light processors (DLP).

Stereolithography 

In Stereolithography, a laser focuses its beam on a set of mirrors called galvanometers, or galvos for short. These mirrors then reflect this hyper-focused beam of light into a vat of resin. Resin is a mix of polymers that appears like an oily substance. 


When the galvos focus the laser on the resin, the resin cures into a solid form. Similarly to the FDM, the object is cured point-to-point, like someone is drawing it with a pen. But the laser is controlled by an automatic mechanism that makes it much faster than a human hand! The mirrors reflect the laser along both an x- and y-axis, creating a cross-section for the object.

Digital Light Processing

For DLP, you replace the laser with a lamp. This creates an advantage. Instead of tracing the shape of each layer point-wise like the stereolithographic method, the light can project that layer’s shape in one flash. This saves considerable time and makes it a much faster method. 


The LED or UV light flashes square pixels called voxels, and the design for each layer is cured into the resin. With each layer solidified, the object is lifted to allow more resin to flow underneath. Then, it’s dropped back down for the next layer to be cured.


You may remember with the FDM printer, support structures had to be built so the print didn’t distort. The same thing is required for both SLA and DLP printers. 


On ​The Market

Because the operation of SLA and DLP printers is more difficult than the FDP, overall costs are a little higher, and fewer are purchased. Jewelry shops and dental labs often buy their own SLA printer. 


One example of a lower-end resin-based printer is the Moai Peopoly for $1,695. You don’t just go out and buy one of these unless you’re serious! This particular model was developed using a Kickstarter fundraiser and comes as an optional Do-It-Yourself Kit.


What’s ​Its ​Function?

One of the standout features of the SLA-produced objects is what’s known as isotropy. This fancy word just means there’s an equal amount of resin in each layer, which gives the object certain characteristics. Isotropy can help with water tightness and predictable performance when used as parts. In other words, stereolithographic printing makes a well-balanced object.


Due to this excellence in water tightness, you may find a coffee maker or other liquid container is made using stereolithography. 


Both SLA and DLP are known for having the finest finish among the different process of 3D printing. That means the result is nice to look at and shiny: a truly finished product. The company Gillette uses SLA printing to produce some of its sleek shaving razors!

Powder Bed Fusion Printers

3d printing tools

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Now that we’ve covered thermoplastic extruders, resin-based polymerizers--what’s next? Ah! The Powder Bed Fusion printers. There are four distinct kinds of this type of printer, but they all share the mode of printing in common.


How It Works

While the material and method can vary, all powder bed fusion printers use some heat or light to fuse powder particles in a build area. 


These printers are a lot like the DLP and its light, which flashes onto the resin and cures part of it to form the layer of the object. But instead of resin, the thermal source of the printer flashes onto powder particles. These particles are heated to just below the substance’s melting point. 


A recoating blade moves a thin layer of powder across the build area, and then the thermal source flashes its design. This fuses the particles. 


Immediately after, the recoating blade shoves a new layer of powder on top of the build area, and the process repeats. So rather than layering with a thermoplastic from point-to-point as with FDM, or with light onto the resin, these printers fuse powder particles.


One of the perks of this method is that support structures aren’t needed. Instead, the powder that is not fused with the object continues to surround the fused parts. Once the piece is finished, you just have to pull it out of the powder and brush it off a bit. Since you don’t have to create support structures, you save on material.


The Different Fusion Types

The more common fusion print is called Selective Laser Sintering (SLS). This process uses polymers similar to SLA. Sintering just means a solid is fused without melting down to a liquid. This process of printing is often higher cost, but SLS-made parts can have complex shapes and sizes, and they are strong. It does take a little longer than your normal SLA process. 


You can also use a Powder Bed Fusion printer using metals! Most people don’t believe you can 3D print with metal, but this is potentially the most significant change 3D printing has brought about in manufacturing. Parts that could have only been made in a metal factory can now be adjusted or built by a small-time mechanic. 


Some fusion printers use alloys and others use elements. This is the main difference between the Direct Metal Layer Sintering (DMLS) printers and the Selective Layer Melting (SLM) printers. Where a DMLS print only melds molecules together, the SLM printer fully melts the metal powder. SLM-printed metal objects then have a single melting temperature, unlike DMLS.


The final Fusion type is called an Electron Beam Melting (EBM) printer. These use an intense beam of energy to manufacture the part more quickly. But because of the strength of the beam, most of the parts have a larger size.


On the Market 

Powder Fusion Bed printers make sturdy, durable parts that are used in heavy-duty industries like cars and aerospace technologies. Particularly the metal fusion printers create the toughest items. Because of this, you can expect the DMLS, SLM, and EBM printers to be the most expensive printers you can find.


Take, for example, the ProX DMP 300--which you can get for a tidy $250,000. These are no joke. Hobbyists won’t be manufacturing their metal parts any time soon with this price range. But heavier industries seem to be increasing their dependence on 3D metal printers, which is a drastic switch from traditional metal-working.

Jetting

printer

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The type of 3D printer that looks and acts most like your typical paper printer is the Jetting printer. There are several different kinds. Two are material jetting printers, and the others are binder jetting. 


Material Jetting (MJ)

A Material Jetting printer’s specific approach is to drop a material onto a build plate where it cures into a layer of the object. A normal MJ will simply drop light-sensitive polymers onto the build plate. As the light hits it, it solidifies, and the layer is constructed. 


The MJ operates just like an inkjet printer using dye on a paper to print a document. Instead of ink, photopolymers drop out. This contrasts with most other 3D printers due to its line-wise orientation. An MJ drops polymers a line at a time instead of a point or flash at a time. This allows for speed and for even multiple objects to be layered at the same time, within limits.


Drop On Demand (DOD)

DODs use pretty much the same technology as the MJs. Drops of polymers fall to create the structure and light cures substance. However, DOD printers have two different inkjets: one for dropping for the build, another for dropping for support structures. Furthermore, the DOD has a “fly-cutter” which scrapes across the top of the build area after each layer is dropped. 


Sand Binder Jetting

Binder jetting is different from material jetting. Where material jetting drops the curing material itself onto a board plate, the binder jetting acts more like the SLS. With the SLS, the thermal source sinters the powder on the build area. The same action happens with binder jetting; only instead of sintering, a binding agent is dropped onto the layer of powder below. 


The binding agent creates the structure as it falls. After each layer is printed, the build area lowers to allow for a new uncured layer of powder to be moved across. 


To keep costs low, you can use a Sand Binder Jetting printer. One possible result is an object made of sand. This is ideal for a metalworking factory looking to make casts. Once you make the cast with the 3D printer, you can pour your molten metal into it, let it harden, and then break off the sand cast.


Metal Binder Jetting

The Metal Binder Jetting printer is the same thing, but using metal droplets. And after you’ve printed the object, you’re not done. You have to place the printed object in a furnace to burn away the binding agent. But because there are still air-holes in the object, you have to fill it with bronze. This gives the metal a better density.


This method of printing with metal is not as strong as using the Powder Bed Fusion printers. 


What’s ​Its ​Function?

One of the more fascinating functions of a binder jetting 3D printer is in the use of producing pills. In 2015, the FDA approved the first 3D-printed pill. Since 3D printers can manufacture unique geometries, pharmaceutical companies are using this power to create pills that are especially porous. This allows for a more effective dosage in a single pill.


To create a pill, the jets of the printer release binding agents into a bed of the drug in powder form. What can 3D printers not print?

Lamination Object Manufacturing

3d printing

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Our last and simplest 3D printer is the Lamination printer. The basic idea of a LOM printer is to take sheets of any material, cut it into layers, and then stack them up. A simple adhesive usually keeps the layers together. The most common type of LOM material is paper. 


When the paper is fit together in this laminate way, it actually takes on some of the characteristics of wood. It can be sanded and cut similarly. 


Since the material is super cheap, this type of 3D printing may be the cheapest of all the types. But since it doesn’t have as much flair, it is lesser-known. 


Typically, people use LOM printers using paper. However, it isn’t unheard of for people to use sheets of metal or plastic in the same way. It is a far less technical process and typically comes in handy for a quick job with limited resources.

An Exciting, Disruptive Technology


And that concludes our rundown of the five types of 3D printers and their unique functions. The time is now to learn more about this exciting technology that has already disrupted innovation in many major industries. 

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