Living in the fast lane with Lisa X 3D Printing Processes

Visiting Sinterit, the leader in compact SLS 3D printers, is always fun. Cracow, where the company is based, is a beautiful city and even the recent global tensions can ruin the welcoming atmosphere. It had been two years since we last visited to test and review their Lisa Pro machine. Then COVID came, just as the company began moving into the new, much larger facility. In the meantime, Formlabs, the market leader in the affordable SLA segment and Sinterit’s most credible competitor in the compact SLS segment, launched its machine after almost four years of announcements. The Polish company, founded by ex-Google developers and led by CEO Maxime Polesello could have been overwhelmed. Instead, the entire management team decided to focus on new product development and training for its employees. The result is that now, two years later, Sinterit is settled in a large new facility, with a highly organized assembly line, one ambitious product, Lisa X, hitting the market and one more, perhaps even more ambitious, NILS, getting ready to do so soon. When the opportunity came to do another test, this time with the Lisa X, I jumped and I was not disappointed.

Recently I have been playing around with some filament and resin-based 3D printers courtesy of Anycubic. Even desktop systems have come a long way. Using them regularly for projects has helped me better understand the challenges of these two 3D printing technologies and the benefits of SLS (one thing is to know you don’t need supports in SLS and another is to actually not use them when planning a print job). At the same time, the SLS powder itself presents challenges and I was curious to learn how Sinterit is addressing them via its new PHS (Powder Handling Station), which comes as a complete solution with Lisa X and the large Sandblaster (and software) with modular solutions starting at just €9,999. Last time, with the Lisa Pro, I needed a significant amount of support to complete my first print. This time, with some more actual 3D printing experience behind me, I intended to go through the entire workflow almost entirely by myself.

Phase 1: preparing the print job

The first step, before getting to the fun part with the hardware and materials, is preparing the file for print. This can almost be completely automated if you want it to be, but Sinterit also gives its customers the possibility to modify over 30 different print parameters. These features are for experts and researchers who need to try and test their own materials, since Lisa X, like all of Sinterit’s platforms, is completely open.

More experienced users are able to easily modify heating parameters, which are crucial in SLS. These 22 heating elements spread across four heating zones enable users to strictly control the temperature variations inside the printer. The resulting array of options for modifying and adjusting parameters allows you to optimize the printing process for developed materials, test new research methodologies, and make top-quality printouts.

I am looking at the printer from the point of view of someone who needs to use it just to print – to either provide a service or get parts and prototypes done within a company. In this case there are some things to keep in mind to ensure the part prints optimally, such as orientation and space between the different parts staked inside your build. However, just the fact that you can place the part anywhere inside the three-dimensional build volume and not need to support the overhangs in any way makes the print preparation process much faster. Sure, this is the same for any compact SLS machine but this one has a build volume of 130 x 180 x 330 mm, with a print speed of 1.4 cm per hour making it close to SLS systems priced 5 to 10 times more.

For our test model, I downloaded a Halo Master Chief 3D printable figure from Gambody. Gambody, an online 3D printable model marketplace that was founded in Ukraine, is great because it makes its models available for specific technologies. This means that I was able to download a specific version of Master Chief for filament extrusion and stereolithography, as well as the one for SLS, which helps further compare the benefits of the technology. For example, with both filament extrusion and stereolithography, you need to print the figure in several different parts with many supports and a platform that needs to be removed. In SLS you just put the entire model in the Sinterit software, you orient it, and you are done.

Phase 2: preparing the printer

Preparing the 3D printer is probably the most complex part of SLS 3D printing, especially if compared to other processes. Filaments are easier to handle and even liquid photopolymer resins, while messy and possibly toxic, are easier to control than fine powders. That is true for both the operator and the machine and it means that an SLS 3D printer must perform several checks of all its systems every time it is used in order to ensure optimal outcomes. Fortunately, the Lisa X does all these checks by itself, with the operator – me – only having to follow a simple step-by-step procedure while the machine does most of the hard work. In order to start this procedure, all I had to do was turn the machine on and give it the go-ahead.

While the Lisa X, like most professional systems, now uses a galvo-mirror setup to control the laser that melts the powder, a compact SLS system has many moving parts, from the platform to the recoater, to several sensors and lights. The Lisa X keeps track of exactly how much time has passed since each part was checked or replaced and always reminds the operator to perform cleaning and replacement procedures as needed. The operator can choose to follow this sound advice or – at his or her own risk – not. Once the procedure was complete, Lisa X indicated when and how to unlock its upper cover.

At this point, we proceeded to fill the machine with powder. Pretty much all the unmelted powder from previous prints can be reused. Sinterit qualified nine official materials, starting with PA 12 Smooth (which we used for our prints) and PA 11 Onyx, which are the most commonly used materials in compact SLS. Upcoming materials for Lisa X include polypropylene and several elastomers (TPU and TPE), as well as CF composite nylon and ESD nylon for engineering applications.

Phase 3: getting ready to print

There are some manual steps you have to complete before you print, but nothing much more demanding than any extrusion or vat photopolymerization 3D printer. The powder bed needs to be flattened and the rails cleaned of the excess powder so that the recoater can move smoothly and add the new powder after each layer is sintered.

After that’s done we just close it up. The machine locks and is now ready to go. The entire procedure only took less than 10 minutes and that’s because I did not know what I was doing and was afraid of doing something wrong. But it seems clear to me that this compact SLS machine is now almost as easy – if not easier – to use as most similarly priced prosumer filament extrusion and stereolithographic systems.

Phase 4: printing

The file can be uploaded via WiFi or a USB key inserted in the front of the machine and all previously uploaded files can be stored in the system’s memory. The touch screen makes it easy to scroll through and give the go-ahead. Before doing that the machine will give another update on the status of various sensors, laser sources, scanners, cameras, lights and other parts, suggesting maintenance when needed. We can decide to skip through these this time. The Lisa X’s IR Fiber Coupled Diode Laser is rated for over 30,000 hours of operation but any SLS system does have to be regularly cleaned and maintained since the powder tends to get everywhere.

The actual printing is the easiest part of the entire process. I only had to press print and wait. The best part is that printing is fast, so much faster than the previous Lisa Pro model. The build speed of up to 14 mm/h means that the entire build volume of 130 x 180 x 330 mm can be printed usually within 24 hours, which means you can print up to five full builds per week. If you consider that smaller parts can be stacked, it get really close to a small production system.

Phase 5: extracting the build

For any 3D printing technology, extracting the build, cleaning and post-processing is probably the longest part of the printing cycle. Thanks to Sinterit’s new PHS it is a much more streamlined, automated and fun procedure, which takes significantly less time than support removal in filament extrusion, even with soluble supports.

First, we need to extract the build. According to Sinterit data, the printing and cooldown process combined takes up to 40% less time than any other compact SLS 3D printer on the market which meant we did not have to wait long (under 24 hours). In order to do extract the build, I used a specific two-part assembly that allowed me to pick the entire powder bed and discharge it directly into the PHS chamber. The remaining powder could be vacuumed via a suction handle. It is all collected into the powder recycler where it goes through the built-in sieving module to finally end up in the 20-liter integrated powder container.

Phase 6: post-printing

The vacuum system is the same. In order to activate the powder collection on the PHS I just plugged the vacuum tube into the machine and shifted between the vacuuming and sifting commands on the digital control panel. This system makes it possible to clean the printer and collect the unused powder in about 10 minutes.

Compatible with both of Sinterit’s Sandblasters, the PHS comes with an ATEX Vacuum to clean and collect unsintered powder and prepare it for your next print. The powder can then be easily poured into the Sinterit Sieve, or remain closed in the container and left for further processing.

After the powder collection procedure was completed, I simply unplugged the vacuum tube, shifted back to vacuuming, and used it to clean up the remaining powder on the build and on the PHS surface. Interestingly the PHS’ vacuum system uses several 3D printed accessories to get into every nook and cranny.

After you are down vacuuming up all the excess powder, you just put the cover back on and the machine is ready to go for the next run. All this was done inside an office environment with minimal powder dispersion.

Phase 6: cleaning up

The last phase of an SLS printing workflow is sandblasting. The full Sinterit Lisa X solution includes a sandblaster but any sandblaster can be used as well. In this case, we used one of the sandblasters in Sinterit’s test laboratory so that the experts there could give me some indications on how to use it. After a few minutes of sandblasting the action figures were ready.

As you can see, while this was not a technical part or component demanding tight tolerances, it is a very intricate complex model, both in terms of the details and overall geometry. The fact that it is fully dense also makes it harder to print properly, due to possible deformation during heating and cooling, but as you can see in the images, the models are perfectly stable. Making the same action figure on an SLA system required the model to be split into 7 different parts, each to be printed separately and with supports. The same is true for the FDM/FFF version. Here, we printed two action figures in one run, which took just over 12 hours.

On the following day, the Sinterit team also completed the print of another large-size version of Halo’s Master Chief, filling up the maximum build volume of the Lisa X. The result, in the photos below, is nothing short of spectacular. This is no toy, but it’s an ideal solution for laboratories, professional studios, factories and even 3D printer farms. The global market for compact SLS is wide open and Lisa X is taking the fast lane to conquer it.

Halo 3D model available on Gambody (https://www.gambody.com/3d-models/halo-master-chief)

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Author: Davide Sher