While modern stereolithography (SLA) printers have come on in leaps and bounds in recent years, there are still two factors restraining their use in a manufacturing setting:
Print volume, and print speed.
However, new 3D printing technologies are hitting the market all the time. In 2019 when researchers from Northwestern University unveiled their HARP (High-Area Rapid Printing) technology, it didn’t take long for AZUL 3D to create a printer capable of speeds and throughput that could revolutionize how we approach industrial-scale SLA printing.
The Challenge in Conventional SLA (stereolithography)
Stereolithography (SLA) printing, uses photocurable liquid resins which are cured using UV light from a laser, projector, or LED screen.
Compared to Fused Deposition Modeling (FDM) printing, SLA printers can print finer detail and the finished product lacks the characteristic deposition lines that make finishing an FDM print such a laborious process.
There are, however, some drawbacks to using SLA printing.
In the home printing market, the hardened photocurable liquid resin is prevented from adhering to the LED screen through the use of a Fluorinated ethylene propylene (FEP) film.
However, this system, where each layer of the print is mechanically removed from the FEP causes suction which can, in turn, cause the print to become detached from the print bed.
Reducing the lift speed of the print bed reduces the suction effect, but significantly increases the print time.
Creating Faster and Larger Printers
New 3D printing technologies, such as using gaseous oxygen to create a dead layer between the print and the base of the resin vat, removed the issue of the suction caused by the previous FEP system.
This allowed for much faster printing times, but actually exacerbated one of the other major issues that impeded the advance towards larger and faster SLA printers, heat buildup.
The photoreactive polymerization that is the basis of SLA printing is a highly exothermic process, producing large amounts of heat.
Gaseous oxygen actually acts as a thermal insulator, increasing the heat build-up to the point where it severely limits the size and speed of the printing process.
AZUL’s Innovative Solution: HARP
The Northwestern University team found the answer to the heat build-up problem in the use of a bed of flowing immiscible fluorinated oil.
The moving oil creates an effect analogous to hydroplaning your car on a rainy day between the resin and the UV light source that allows for faster, non-adhering printing.
At the same time, the oil did not function as a thermal insulator. In fact, since it was flowing, it could be cycled through a heat exchanger to act as a cooling method.
The HARP method had other advantages as well. The oil could be used to heat the print bed before printing and it could also be filtered to remove micro-particles that scatter the UV light and reduce the fine definition of the print’s details.
Additionally, because the switch from gaseous oxygen to fluorinated oil meant that the HARP system could be used to print with resins that would normally react poorly to the presence of oxygen.
How It Could Disrupt the Market Today and in the Future
Using the HARP system, AZUL was able to create new types of 3D printers with 2000 times the liquid throughput than market leaders, able to print at 20 times the scale and 1000 times the speed of anything else available at the time.
HARP 3D printers are able to print a structure that is 12 x 12 x 48 inches in as little as three hours. The same technology can also be used to print large amounts of smaller prints very rapidly.
HARP 3D printers have the ability to disrupt the market today and the future by combining the fine detail and excellent finish of SLA printing with an ultra-rapid print time and high build volume, while still being able to print in a wide variety of photocurable liquid resins.
Applications in the Market
Azul 3D has already announced a collaboration with DuPont Electronics and Imaging to use its HARP technology to revolutionize how electrical components are produced.
With HARP allowing speeds comparable with injection molding, producing far more rapid print times than its competitors, and being able to use industrial-grade materials, this new 3D printing technology is capable of providing a rapid and uniquely customizable production process.
HARP allows manufacturers to offer all the cost-saving and customization benefits of 3D printing with the speed and scale of traditional injection molding processes.
The wide-ranging benefits of HARP 3D printing technology have a huge range of uses-cases across multiple industries.
Azul 3D also used HARP technology by mass-producing medical face shields to help protect health care workers facing COVID-19 crisis.
Currently, one of the main uses of additive manufacturing is to produce prototypes.
Not only does the HARP technology increase the speed, scale, and detail at which these prototypes can be produced, but the huge leap forward in throughput and print size offered by this new 3D printing technology gives it the potential to displace traditional manufacturing technologies altogether.
HARP 3D printers have the potential to be a full-process manufacturing option, with the flexibility and customization options available to take part in the prototyping process, combined with the print speed and print scale to be used as part of the full-scale production process.
This huge step forward in the utility of SLA 3D printing has the potential to completely redefine the place of additive manufacturing in the supply chain, moving it from a solution for specific problems to the perfect solution for a huge number of problems.