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3D Systems VS FormLabs

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3D Systems vs. Formlabs 

Why We Spend $200,000 to Print Large Scale SLA Parts

Formlabs recently posted an article that caught our eye, comparing 3D Systems SLA Machines to  Formlabs machines.  They suggest that in 2021 there is "No Need to Spend $200,000 to Print Large Scale SLA Parts".

As a service bureau, we disagree.

Stereolithography printers by 3D Systems cost around $200,000 USD for a machine with a 15 x 15 x 10 inch (38.1 × 38.1 × 25.4 cm) build platform. The build volume of this machine is quite comparable to the new Formlabs Form 3L machine, which boasts a slightly smaller capacity of 13.2 × 7.9 × 11.8 inches (33.5 × 20 × 30 cm), but comes in at only a fraction of the cost at $11,000 USD.

Formlabs entered the playing field as a fierce competitor, aggressively targeting their new larger frame machines at 3D Systems users, and for good reason. On the surface, their machines seem like a really good deal; more resin availability, easy hot swaps between materials, and a low price tag. This all makes the Formlabs machines very attractive on paper. However, for high volume industrial manufacturers the 3D Systems machines are cheaper to operate, offer significantly higher throughput and accuracy, and require much less labor to operate.

In order to understand these differences, we need to examine how each printer builds parts. 

Inverted VS. Non-inverted SLA

Both the Formlabs Form series and the 3D Systems Projet series printers are built on stereolithography technology, however there is one significant difference in the way they build parts.

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Inverted Stereolithography

Formlabs SLA 3D Printers use a technology called “Low Force Stereolithography” which is an inverted process that uses a  flexible tank and linear illumination to cure layers of parts. After each layer is cured, the part is slowly pulled out of the liquid resin upside down. This introduces significant peeling forces on the print as it separates from the surface of the tank. To mitigate this, as well as gravity, the supports produced need to be very thick and have very large touchpoints. If supports are underbuilt, there is a risk the part will delaminate and fall off, destroying the build.  

The big advantage of this inverted printing technology, and the reason why all low cost SLA printers use it is because it requires very little resin. The vat only needs to be full enough to cover a few layers of the part. Vats can be quickly and easily swapped out in minutes to rapidly construct new materials.

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Non-Inverted Stereolithography

3D Systems machines use non-inverted vat-photopolymerization where parts are printed right side up and the tray drops below the surface of the resin as the part is built. Since parts are dropping into the resin, they require very little support to hold up the part as the liquid resin surrounding the part stabilizes it during printing. Once the part is complete, it rises up out of the vat of resin.

The reason only industrial printers use this technology is because it requires a full vat of resin equivalent to the build volume. This means you have to invest in $10,000 or more in resin to fill the vat before you can even start printing. This technology works very well for ultra-high throughput of a single material, but does not lend itself to hot swapping between materials. Typically one machine will be dedicated to a single 3D printing resin for its entire working life.

Given all of these expensive considerations when investing in a non-inverted 3D Systems SLA printer, why are they so popular in industrial 3D printing?

Fortus 450 Gantry

Industrial SLA Lab using 3D Systems Projet 6000 & 7000 machines

ProJet 7000 vs. Formlabs 3

Example parts used in this comparison can be downloaded here: 3D Systems Clearvue Tile, Formlabs Clear Tile.

We assessed the two machines on four metrics important to volume manufactures such as ourselves:

  • Print setup
  • Print speed
  • Post processing time
  • Accuracy & surface finish. 

Print Setup

Each printer uses its own proprietary 3D print software that comes included with the machine. 3D Systems uses 3D Sprint software, and Formlabs uses Pre-Form. 

3D Sprint offers a number of additional features that fast tracks the preparation of dense builds. For building this tray, we dragged and dropped the part onto the tray, and immediately ran an automated part repair feature that ensures there is no broken geometry. We then used the customizable auto-orientation option, optimized to "limit support area" in this case, and then copied the parts by generating a 6x6 array of parts. To generate supports, we combined all the parts so that supports would be generated for the tray as a whole. This means that supports generated for one part are calculated so that they don't intersect the surrounding parts, which allows for a much higher part density.  We then used the automated quality check to look for any print quality issues, and then exported the tray to the printer. This entire process took less than a minute.  

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Formlabs required us to manually orient the part because the "auto-orient" feature is not customizable and it angled the part too far back. After adjusting the orientation manually, we created a 6x6 array, but since there was no combine function, we had to generate supports for each part individually. This meant that supports from one part intersected the geometry of surrounding parts, which forced us to increase the spacing between parts. We had to either settle for a lower density build of 5x5 or manually edit the supports so that they didn't intersect the other parts.  There was also no way to detect or repair broken files, and Preform doesn't provide any alternatives to sending the tray over the network which prevented us from reviewing the slices in the print file (often a crucial step in troubleshooting).

Formlabs Preform Pre-Processing Time:

 3m 48s

3D Sprint Pre-Processing Time:

56s

Print Speed

3D Systems printers are significantly faster than Formlabs machines. You can see the difference below on a tray with the same quantity of parts. The 3D Systems printer prints the same amount of parts four times faster after controlling for slice height, orientation and build z-height.

FormLabs Form3L Print Time:

 68H

ProJet 7000 Print Time:

19H

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Formlabs Form3L Print Time: 68H

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3D Systems Projet7000 Print Time: 19H

Post Processing

Anyone who has run an SLA printer before knows that printing a part is only half the battle. The bulk of the work is in the post processing and clean up of the part. This includes support removal, curing and post finishing of the part, and is another area where 3D Systems SLA Printers really shine. Since parts are built inside of the liquid, they require very few supports. Most parts can be printed self-supporting with only a few support towers to hold them up. Touchpoints can be as small as 0.1mm and simply break off when you run your fingers along them.

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ProJet 7000 Default Supports

Formlabs supports are much thicker and almost always require the use of pliers or snips to carefully remove them without breaking the part. The density and thickness of the Formlabs supports results in exaggerated "support stubble" on the part, which requires quite a bit of sanding to remove. In contrast, the 3D Systems support breaks off in your hand and any leftover support nubs can be picked off or lightly sanded.  

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Formlabs and 3D Systems support

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FormLabs Support Removal 

Surface Finish

Support nubs leftover on the part can be a significant post processing challenge, and require the technician to access the surface to remove the support defects with sandpaper. These nubs can be extremely apparent on Formlabs prints due to the thicker supports required.

In contrast, 3D Systems SLA printers require very little support structures as there are no gravitational forces on the part. This allows ultra thin features to be printed with little to no risk of breakage during post processing. Additionally, while white parts can be fairly easily sanded, transparent parts immediately lose transparency when sanded. You can see examples below of the same part printed on a 3D Systems machined and a FormLabs machine

The additional labor required to post process Formlabs SLA prints can be significant for large volume manufacturers.  This is especially challenging when printing large, thin walled & delicate parts with difficult to access supports which can add significantly to the post processing time, or result in broken parts requiring costly reprints.

We timed our technician’s per part cleaning times on the same geometry from a 3D Systems printer and Formlabs printer and even for simple geometry such as this tile, the difference was significant.

Formlabs Form3L Post Processing Time:

8M 55s  / part 

ProJet 7000 Post Processing Time:

2M 54s  / part

A significant amount of the additional post processing required on the Formlabs part was spent trimming the supports off without damaging the part. The leftover nubs required a full sand of the surface where the supports were attached. The 3D Systems prints required no sanding whatsoever and the supports all broke off using fingers, requiring no tools. Sandpaper was only used on the bottom edge of the part to remove the nubs where it was most densely supported.

Accuracy

The Projet 6000/7000 printers reliably deliver part print tolerances within +/- 0.2mm, and can be fine calibrated to even higher tolerances. Our machines typically go through monthly calibration cycles where scale bars are printed and measured to produce offset values in each axis, which get entered into the machines.

Formlabs does not allow users to manually calibrate their machines. As such, tolerances on large parts can often be fairly loose and especially noticeable on larger parts. Additionally, the supports on the parts can be significant enough to damage the part and affect part tolerances without careful hand finishing.

This test yielded similar results given the relatively small size of part, with the Projet being slightly more accurate compared to the CAD file. Print tolerances can compound over greater distances, and are more difficult to control for larger parts that span the build volume. This is where the tighter tolerances of the Projet machines can make a big difference.   

Formlabs Form3L Accuracy:

 X: 0.21mm

ProJet 7000 Accuracy:

X: 0.1mm

We also decided to weigh the parts to see how much resin was used for each part, including supports and confirmed that the much thicker supports of the Formlabs machine use significantly more resin for the same geometry. 

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Formlabs part with support

47 grams / 1.65 ounces

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3D Systems part with support

31 grams / 1.09 ounces

Summary

Printer

Formlabs Form 3L/3BL

3D Systems ProJet 6000/7000 HD

Price

Starting at $10,999

Starting at $200,000

Build Volume

13.2 × 7.9 × 11.8 in

15 x 15 x 10 in

Accuracy

Not Given

+/- 0.2mm / 

Print Time

68 hours

19 hours

Post Processing Time

8m 55s / part 

2m 54s / part

Surface Finish

Visible nubs & defects on surface, low clarity

No visible markings, high clarity

Part weight with support

47 grams / 1.65 ounces

31 grams / 1.09 ounces

Conclusion

The Formlabs article fails to do a comprehensive comparison of the entire manufacturing process and part quality from each machine and simply focuses on the entry cost to each technology. We found that there were significant differences in workflow efficiency, quality control, part accuracy, and throughput that made the higher initial investment in a 3D systems machine worth it. We made that investment in order to deliver high quality parts consistently in the long term.