I am about to pull the trigger on a form2 but there is one last detail that has been bothering me. I am torn between a higher end FDM machine that can print in high temp plastics like nylon, polycarbonate and acetal or the form2.
I will likely be using the tough and durable resins almost exclusively, but I have not been able to find infomation on how their material properties change over time and with handling/use. I understand these are UV cured polymers and that continued UV exposure after curing can affect them, but how much? Will the tough resin become as brittle as the clear or will it still have a significant advantage? Is some form of UV protective finish absolutely mandatory?
I intend to use whatever printer I buy for jigs & fixtures, drone parts, and many other objects that will be used and handled on a regular basis. I have searched and read a ton on high end filaments being printed with good success. I was leaning toward the form2 because of the great resolution and detail.
I have both the form2 and a fdm printer (a heavily customized Replicator2X).
I specifically brought the form2 for its detail on smaller prints.
My fdm printer can indeed print in a variety of materials, most will require some sort of protection if used extensively outside.
However, I cant get close to the quality finish of the form2.
Oh, and before anyone mentions, I also have access to a rather expensive Stratasys FDM printer, although sometimes better than my Replicator 2x, its still suffers from finer details.
Both printers have a place. Lets use a completely 3d printed truggy as an example.
Large pieces are printed on FDM printer, smaller detailed parts printed on the Form2.
Ive tried printing the gear box components on the FDM, now about to use the tough resin on Form2
On the other hand, a full size guitar or ukulele, is great printed on the fdm printer.
It really depends what you want to print. I am very happy with both, both having a specific use.
I understand what you mean. It seems very wasteful to print large non-critical parts with an SLA machine due to the expense. It is also overkill on resolution as you mentioned. I have also used several commercial FDM machines and as long as you work within their limits, the parts produced are very usable.
Everything I want to make easily fits inside the build area of the form2, my concern is long term stability of the material properties.
What type of protection do you find you need on your FDM parts? ABS, Nylon, PC, and Acetal are fairly resistant to just about anything. I realize there are mechanical issues and possible delamination, but optimizing processing parameters should be able to address that.
I am coming from a world of resistance welding and insert molding (Manufacturing engineer turned controls engineer), where I am used to having to dial a process in to achieve the desired properties in the finished part. Polycarbonate in particular is not that exotic and with a proper extruder, heated bed, and enclosed heated build chamber the mechanical properties would be excellent.
Plastics in general break down in the sun even when UV protected. The SLA prints suffer more degradation than an fdm would because they are uv cured and continue to cure. Because the quality of the prints from the Form1 and SLA in general are much better I use them as Master Prints then make molds from them and cast new permanent parts in various materials either in metals or in urethanes. I have been using Smooth-On as a supplier for urethanes and they have a uv blocker called Sun Devil where you add 1% by volume of material mixed.
I would have thought that would be one of the things they tested while developing new resins. I did contact FL support and they apparently hadn’t even thought about that part.
On the plus side, I was in touch with a FL distributor that has customers that use the engineering materials regularly. Their response was:
“The tough resin has proven outstanding for making jigs and fixtures etc. I have several customers that are using it very successfully and getting outstanding results. All SLA resins are UV cured so they will continue to cure for their entire life. With the exception of the fact that over time there is some change in the color of the print, nothing else varies. No changes in material properties or strength etc. Hope this helps.” keep in mind this response was coming from someone trying to sell me something
So, promising, however the new tough resin hasn’t been out long.
A good read, thanks. The two main factors relating to SLA printing that I pulled from that:
“A relationship between mechanical properties and degree of cure was established. Tensile properties improved, yet impact strength and elongation at break were reduced, indicating that during the experiment, the material became stiff and more brittle. This confirmed that even after post-curing with UV radiation, SLA products are only partially cured”
“The effect of ageing in three different environments: ambient, desiccated and desiccated but after 48-h pre-conditioning in an environmental chamber at 23 ± 2 °C and 50 ± 5 % RH was studied over periods of 4, 30 and 120 days. A decrease in mechanical properties was observed in pre-conditioned samples due to the influence of humidity. The ultimate stress values increased over a period of 30 days, following which a decrease was noticed, indicating the onset of degradation following a short initial period of curing”
Still no explanation as to the amount of degradation and over what lifespan. Nor, did they compare with any sort of UV protection applied. I’d also like to compare against the traditional resins I use for casting.
After being fully post-cured, the mechanical properties of a print won’t continue to change even with continued UV exposure. Using the recommend curing settings theoretically completes all of the photo-polymerization reactions and stabilizes the mechanical properties. Most plastics do inherently degrade somewhat in UV but our materials are pretty resistant.
Thank you for the information! Thats what I have been looking to hear. Curious though, has Form Labs done any long term testing? Do you have parts that have been lying around for years? I contacted support prior to engaging in this thread and they had no answer for me.
You can spray the parts with a uv protector that would help extend the life of an sla print. Personally I don’t rely on a printed part that is exposed to light for long term. One of my first prints a few years back was in the gray resin 1 and that part was a simple wire hanger. It finally just crumbled a week or so ago. The clip was exposed to regular room light, not directly in the sun.
Not that my use is considered testing but I made rim caps for my truck. I believe they have been on the truck for a year and a half. They have not cracked or fallen apart. I gather that one will get destroyed while offr oading before the plastic degrades. They are made in Black (I believe V1).
With New England weather, they are doing quite well. I have been very impressed.
Thank you for the info. I am glad someone from Formlabs was able to jump in. I know there is a lot of chemistry going on behind the scenes and that there are several types of UV cure resins. What exactly gives the FL resin it’s stability? What is the basic chemistry of the resin? I understand you cannot give specifics but I’m curious.
I think your response seals the deal for me as that was my biggest concern. Ken however seems to have parts that suggest the other resins (standard?) may not behave the same as the tough resin.
I would think the UV stability could easily be tested by accelerated aging in a strong UV source over a period of a few weeks. Several identical samples put in at the same time and taken out at fixed intervals for testing. I unfortunately do not have a printer, and do not have the equipment to do any testing. Moisture/humidity could be tested similarly to the paper I linked with a closed desiccant filled container as the control. Just a thought.
A few months ago, I asked one of their materials guys about doing some artificial aging. Which would tell us how accelerated aging affects a print, but not necessarily how the print will react in the real world. There’s the Image Permanence Lab in Rochester and Henry WIlhelm’s outfit out in Grinnell Iowa that could be enlisted.
There just doesn’t seem to be much interest at FL in doing a series of controlled tests. No market demand.
Coming from the world of photography before I turned to sculpture, I’m sensitive to permanence. Many photographic processes turned out to be fugitive. I worry.
The oldest Formlabs I have are 2 years old. Some are getting brittle, but I have no idea what I put them through. Might have been prolonged soaking in IPA, as in, oh crap, left it in for a week when I was traveling. So no help there.
As for me, the pieces I really care about are used as maquettes in lost wax bronze casting, using grey and tough. Bronze is gonna hold up. Now all I have to worry about is the patinas.
The people at RIT are very good. I worked with Denis Cormier a little bit in the Brinkman Lab with some of their printers. I imagine they have been acquiring more equipment since I left and they may have some interest in doing some tests.
My understanding of the basic chemistry is you have acrylate chains being formed by a photo-polymerization reaction. These acrylate chains are densely cross-linked which helps with long-term stability.
For each of our resins, post-curing will complete most all of the photo-polymerization reactions. The standard resins do have a higher stiffness (measured by Young’ modulus) than tough resin which is why you’ll notice they become more brittle after being fully post-cured.
UV does degrade pretty much anything organic but our resins are more resistant than typical engineering thermoplastics.
so, would leaving some select pieces in my UV chamber for long periods of time effectively test long term exposure? Or would I need to take into consideration humidity or other elements?
Long-term exposure in a UV chamber might degrade the part. UV exposure degrades all organic materials, but our resins are more resistant than many common plastics like ABS. UV exposure in a cure chamber will be significantly greater than that of a natural environment and we’ve tested parts outside for over a year outside and haven’t seen any obvious wear.
