Last updated on 18 February 2020
Additive manufacturing has fundamentally changed the way complex, hollow composite parts are created. Covestro Additive Manufacturing provides an unparalleled solution for producing tough, complex hollow composite parts with a superb surface finish and high feature detail.
No other solution allows such easy removal after the autoclave process, enabling multiple iterations to be implemented quickly. Resulting in tough, complex hollow composite parts with superb surface finish and high feature detail.
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|Ec||15.0 mJ/cm2||[critical exposure]|
|Dp||5.50 mils||[slope of cure-depth vs. In (E) curve]|
Please adhere to the following guidelines:
We recommend the following room conditions:
When replacing material, make sure you clean the vat thoroughly, dispose of used material and cleaning products (solvents, paper towels, etc.) properly and follow vat installation procedures.
Contact your equipment supplier for up-to-date technical support for your equipment. Below are a few common checks that will help you build parts successfully:
Composite material settles over time and so requires occasional mixing. To ensure proper consistency, adhere to the following guidelines:
With any composite or filled material, it is important to mix the material prior to use. Using a small “paddle” attached to a hand drill, mix the material in the bottle for 30 seconds to 1 minute. Move the paddle around the inside of the bottle—including up and down on the inner edges—to make sure all the material has a homogenous consistency.
Once pre-mixed, the material is ready to add to the vat. A fine mesh sieve can be used to catch any “unmixed” lumps of material and prevent them from entering the vat. If you don’t have a sieve, pour the liquid over the platform to give you a better chance of spotting any lumps. If you see lumps, press them through the sieve or platform using a spatula.
We recommend that after introducing any new refresh material to the vat, you run a 15-minute “Platform Stir.” This will mix the new resin with any remnants of the material that is present in the vat. You can then continue to build.
If the resin is for use in a new, full vat fill or after a vat sieve procedure, we recommend you undertake a “Paddle Stir” of at least 2 hours on a medium speed setting. This will help blend the material batches together into a uniform, homogeneous consistency. It will also allow bubbles of trapped air to be released from the body of the material. We recommend you place the blade part of the mixing paddle as close to the bottom of the vat as possible. Doing this will avoid any potential settlement build up.
To maintain the life expectancy of your material, all the benefits of process speed and material stability, you should follow the following mixing regime:
Remove the resin from the vat and pass it through a fine mesh sieve to remove foreign bodies, such as support structures, that may have entered the vat. This should be done at least every 3 months.
During this operation, any settlement should be mixed back into the resin that has been removed during the sieve operation.
Failure to run a sieve operation can result in continual settlement build up and, eventually, the formation of a hard-packed layer. This “hard pack” layer can cause issues for the elevator during part builds. Hard pack settlement cannot be mixed back into the material and must be removed and disposed.
Build parameters are subject to site conditions and machine efficiency. The parameters mentioned below can be considered base settings that you can tweak for improved styles.
Check to see that the Zephyr blade is clean of any residue by running a gloved finger along each side of the blade. If there is any residue, gently wipe it off with the proper tool.
Before beginning a new build, always check the Zephyr blade to ensure there were no changes after any build crash or other adverse events that may have changed the gap.
Also, check that the resin level in the blade is set to the halfway point. On builds with large flat or trapped volumes, check that the blade does not run out of material. If it does, material starvation could be causing it to give an incomplete part re-coating.
The build style of choice is Exact™ (Old Aces™). It offers the best:
To achieve an even thickness using a solid-state laser with Exact™, perform the following calculation: Smax = 0.4* DL * FL *1000
The minimum beam diameter (in X or Y directions) should be used when calculating the maximum scan speed.
To ensure that the Smax is properly calibrated, please refer to the following chart of common stereolithography machines.
The Smax should not exceed the recommended hatch speed for the machine being used.
During a build, you may find that excess material builds up on flat surfaces and in cavities. There are two ways to clean these:
After thoroughly air-drying the parts and checking that they are free from liquid resin residue, UV post-cure the parts for 20 minutes, rotating the part once after 10 minutes.
To increase the heat resistance and tensile strength of parts made with Somos® var_product, we recommend you thermally post-cure them. Follow these steps to thermally post-cure your parts:
In some areas, partially cured or uncured waste UV material may be classified as hazardous waste, and requires special packaging.
Contact the governmental or other body that regulates waste disposal in your area to determine the disposal protocols.
Packaging-Transportation-Disposal methods must prevent any form of human contact with the waste UV material, even if it is classified as nonhazardous or unregulated. This therefore precludes the use of disposal methods that might result in groundwater or surface water contamination.
Solvents should be isolated in a sealed, marked container and disposed of as “hazardous waste” in accordance with all applicable laws and regulations.
Soiled clothing, empty containers, etc., should be disposed of in accordance with the applicable “hazardous waste” guidelines. If any of these items contain uncured or partially cured UV-curable materials, the disposal method used must prevent any form of human contact, including any that could result in groundwater or surface water contamination.
Below are some examples of common issues and troubleshooting solutions. Consult this part of the guide if you are having difficulties and do not hesitate to contact our Tech Support.
Delamination occurs on the bottom layer of parts at the corners or on part edges.
Solution: Check Blade
Have the physical gap on your re-coating blade checked.
Watch the buildup of the first few layers of the part to determine that the surface is being properly coated with material. Check for signs of material starvation or de-wetting.
The top surface of the part is not smooth and level.
Solution: Check Re-coating Blade
This condition is somewhat common and arises due to the viscosity of the material and the presence of debris that may become suspended in it.
Check the re-coating blade to make sure the bottom surface is clean and filter debris from the vat.
It is very important that you maintain the correct material viscosity in your stereolithography machine. The viscosity can increase over time, and this can cause problems in building parts. If the viscosity increase is severe enough, the material may have to be replaced, resulting in significant expense and lost production time.
If increasing viscosity is identified early, the material can, in most cases, be saved. Regularly measuring resin viscosity can provide an early indication of the problem. This must be done even if the machine is not used often, as resin viscosity can change even when the machine is idle.
Depending on the viscosity range of the material you want to test, use the appropriate-sized cup, based on Zahn Cups guidelines. You will also need a long-stem thermometer that mounts onto the Zahn cup handle and a stop watch.
Remember: Whenever you have material in your machine, measure and record its viscosity once a week.
|Seconds||Approximate Viscosity (CPS)|
Get in touch with our experts to discuss how Covestro can help you tap into the full potential of additive manufacturing.