Enter Formlabs and Low Force Stereolithography (LFS), the core of its third-generation 3D printers: the Form 3 and the Form 3L.
Inverted & Low Force Stereolithography
One of Formlabs’ biggest innovations in SLA was to turn the 3D printing process on its head, reducing the amount of resin needed to fill the vat where it’s photopolymerized. This enabled the company to produce an SLA 3D printer with a smaller footprint at a more affordable price point.
“That’s huge,” explained Jennifer Milne, Product Marketing Lead at Formlabs, “You’re not wasting material since you only use what you need from the cartridge and you can easily switch resins.” The trade-off is that parts produced in this way are subject to gravity and other forces pulling them off the build platform—something Formlabs has been working to address from the beginning.
As Milne explained it: “The technical challenge is how do you tilt something enough that it will scrape through the build surface but easily peel away from the print surface? In the Form 1, we had a very clinical peel mechanism with a tilt motor on the left-hand side; it would tilt in one direction and pull straight back, and that created a certain amount of force on the part.”
“In the Form 2,” Milne continued, “the tanks have a soft silicon material and we slide them to the side as we lift up to create a sheering motion. That’s much lower force than the tilt motion we had in the Form 1. Now, in the Form 3, we’ve moved to a completely flexible tank, so there’s no hard substrate—it’s a film held in tension and as the Light Processing Unit moves across it, the film is able to give a little. So, because the film has that give to it, the motion of lifting straight up creates a sort of parabola in the film so that it’s peeling away from the edges—like a sticker coming off something—rather than a straight pull.”
In addition to the flexible tank, the LPU marks another improvement between the second- to third-generation Formlabs 3D printers. The Form 2 uses two galvanometers for positioning the laser in the X- and Y- axes, while the LPU in the Form 3 and Form 3L uses one galvanometer for the Y-axis and a linear stacker motor that moves the entire unit for the X-axis.
“There was a lot of talk about this,” Milne commented. “Our engineers love the linear stacker because it’s digital and it’s more predictable: it moves in discrete 25-micron steps.”
Revamping the LPU brings several benefits, such as making it easier to replace and inuring the machine against contamination on the shop floor. “The whole LPU is replaceable,” Milne explained. “Our intention is that, if there is an issue, rather than the customer sending the entire printer back to us, we can just send them a new LPU that they can install. And when you take the tank out of the Form 3, there are no critical components beneath it and the critical surfaces are protected. For a lot of optical systems, you need to be very careful about contamination if you’re in a dusty workshop, but in the Form 3 that’s all enclosed.”
To learn more about the new LPU and the technology underlying the LFS process, check out the Formlabs Form 3 Product Demo webinar.
Scaling Up SLA
Making maintenance and repair operations easier is obviously a major plus, but the biggest benefit of the new LPU design is its ability to scale. Indeed, it was the demand for a larger 3D printer that led Formlabs to developing the new LPU and LFS process.
“I spoke to one customer who loved their Form 2 and they were emailing me saying, ‘Absolutely make a bigger Form 3, that’s all you need to do: make a bigger printer.’ And that’s because they had to send large parts to a service bureau, which was costing them several thousand dollars a month. So, at a price point of $10,000, we think the 3L will be particularly disruptive.”
Of course, making a larger inverted SLA 3D printer was no simple task. “We couldn’t have just made a bigger Form 2,” Milne explained. “As we get to bigger pieces, you have more weight hanging off the build platform and bigger forces on the part. So, we needed to create a lower force system that would be capable of doing large-volume parts without ripping the part from the build platform.”
Milne also noted the potential issues with smaller angles at the edges of the build plate, which can be accounted for with calibration software but which would be exacerbated by larger build areas. In contrast, the new stereolithography system in the Form 3 and Form 3L is inherently scalable.
Beyond that, LFS on the Form 3 and Form 3L enables parts to have fewer or lighter ports and finer cut points. “You’re saving time at the end of the process in terms of finishing the part and you also have fewer supports marks on the underside,” Milne said.
For similar reasons, the flexible tank reduces the likelihood of two of the most common failure modes in 3D printing: parts not adhering to the build plate or being torn from supports. “If you want a part to stick to the build platform but peel away from the print surface,” Milne said, “the materials need to be cured to a certain green strength so it can withstand the printing process. If we can lower the forces, the parts can be weaker and there are opportunities to print more quickly.”
Advancements in 3D Printing Materials
Milne’s point about 3D printing resins brings us back to the topic of AM innovation, since materials are arguably where the technology has seen the most rapid advancement. “When we launched the Form 2, we had a handful of materials,” she said. “Today we have over 20.” These include biocompatible resins—Dental SG and Dental LT Clear, popular in the dental appliance industry—as well as engineered materials for high-temperature applications or those requiring extra strength or flexibility.
“As an example,” Milne said, “we just released a new material called Draft Resin that was developed to print at 300 micron layers, and we’ve found in a lot of side-by-side comparisons that it’s actually faster than FFF [Fused Filament Fabrication].” One Formlabs customer was able to print parts 20 percent faster than FFF with low-density infill and 40 percent faster with an equivalent solid infill using Draft Resin.
“We’re pretty confident that we have one of the largest materials teams in SLA; we have over 40 materials scientists in-house,” Milne said. “I think stereolithography is a great solution for many applications. Sometimes it’s just a matter of your approach and the materials you use.”
To that point, the combination of Formlabs’ additive material expertise and the company’s LFS technology will conceivably enable the company to develop new materials that take advantage of the low forces involved in the 3D printing process. The consensus within the AM community seems to be that the two biggest roadblocks to 3D printing adoption are materials and expertise. Fortunately, Formlabs appears to be amply equipped to handle both.
To learn more about the Form 3, Low Force Stereolithography and whether it’s right for you, check out the Formlabs Form 3 Product Demo webinar. It covers everything from the underlying technology to the steps needed to set up, print and post-process parts on the Form 3.
For more general information, visit the Formlabs website.
Formlabs has sponsored this post. All opinions are mine. --Ian Wright.