PolyJet – 3D Printing Technologies Simply Explained

PolyJet is a 3D printing technology that builds parts by jetting thousands of photopolymer droplets onto a build platform and solidifying them with a UV light. It’s one of the fastest and most accurate 3D printing technologies currently available.

If you’ve already heard of material jetting (MJ) 3D printing, you may now be thinking that PolyJet sounds very familiar… Well, that’s because it’s effectively the same thing. Confused? Keep reading.

Photopolymer by Any Other Name

Names can sometimes be tricky in the 3D printing industry, with multiple being used for the same technology or product. (Think FDM vs FFF or DMLS vs SLM.) The main reason for this is the many companies trying to get their slice of patent pie.

PolyJet is basically just the name given by Statasys to their MJ printers. Similarly, 3D Systems calls their MJ printers MultiJet.

So where does the PolyJet name come from? Well, there’s a story behind that, too.

A Bit of History

The first 3D printer that jetted photopolymer droplets and cured them with UV light was developed by a company called Objet-Geometries in 2000. They carried the development of the technology, which they called PolyJet, and held a number of patents.

In 2011, Stratasys acquired the company with the goal of expanding the range of their products to MJ solutions. Thus, the name PolyJet remained the same and is now used for printers from Statasys.

At the end of the day, MJ and PolyJet (and MultiJet) are the same technology with different names.

Naturally, since development of the technology is split between two companies, some minor differences exist between their respective devices. Nevertheless, the basic printing principle remains the same.

In the following, we’ll go into more detail on how PolyJet works, what sets it apart from other manufacturer’s MJ printers, and what the advantages and disadvantages are of using the technique.

The anatomy and printing process of a PolyJet 3D printer are the same as for a material jetting 3D printer. As we already have a detailed article on material jetting (MJ) 3D printing, we won’t go into much detail here – just the basics.

As you can tell from the above image, PolyJet printers consist of a material container, a build platform (and its elevator), and a carriage on which UV lights and jetting print heads are mounted.

Before printing begins, photopolymer resin must be poured into the material container and heated. This allows the substance to reach the desired viscosity.

The printing process starts with the carriage moving across the X-axis, across the build platform. As it moves, the print heads selectively jet the resin, in the form of droplets, onto the build platform. Immediately after they’re jetted, the UV lights cure them into an ever-growing solid.

As there are multiple print heads, different materials can be printed at once. An example application of this functionality is a part requiring supports, where the support material builds up at the same time as the main material.

After a single layer is complete, the build platform moves down one layer in height and the process continues until the part is finished.

PolyJet 3D printers work with a range of different materials, amongst which there are even bio-resins.

As mentioned earlier, the two giants leading MJ 3D printing development are Stratasys and 3D Systems. The two main difference between their devices is the type of material used for support structures.

PolyJet, from Stratasys, uses dissolvable support material, which is usually made of polyethylene, propylene, and glycerin.

After printing, parts made on a PolyJet machine are removed from the build platform and exposed to pressurized water. This removes as much support material as possible without dissolving it. Afterwards, the parts emerged in a chemical solution, in which the rest of the supports dissolve, leaving a clean part.

On the other hand, MultiJet 3D printers utilize paraffin wax as a support material. After a part is printed on a MultiJet 3D printer, supports need to be melted away in an oven.

The potential of PolyJet has been recognized by many different industries, which implement the technology to enhance their workflow and save money.

Because PolyJet is a technology that can produce highly detailed parts in a matter of hours, it’s especially ideal for making realistic prototypes. In the making of a prototype, time is literally money, so it’s better not to waste it.

Another great thing about PolyJet is the ability to 3D print with different materials at once. This allows for compex geometries and, once again, saves time (and money).

Apart from prototyping, PolyJet 3D printers can often be found in the dental industry. Modern clinics utilize PolyJet for making 3D printed molds of someone’s mouth based on a previously-taken scan. PolyJet makes this process faster and more accurate than ever before.

Feature image source: Proto3000 / YouTube