Solidator Vat Release Patent

[AndersonTa]

https://www.google.com/patents/DE202013 ... CEEQ6AEwAQ

Interesting read on the patent pending vat release the Solidator uses. Really innovative, using FEP and its oxygen permeable characteristics.

And a read on the oxygen permeability of FEP.

http://onlinelibrary.wiley.com/doi/10.1 ... 260832/pdf

[hp_]

An interesting link on Permeation of FEP film

http://www.magnatexpumps.com/pdf/permeation_effects.pdf

and here is a nice book on permeation of plastics

http://books.google.be/books?id=O4yFcup ... lm&f=false

duponts info on permeation:
http://www.rjchase.com/fep_handbook.pdf

[Benjamin]

Hmm,
i dont get it, how they made a "patent pending" when the complete process is still patented by envision technology?

[Phife]

Im very interested in exactly how the Solidator releases the part.. I took a look at the patent but it doesnt make much sense to me. Can someone break it down for us?

[258cj7]

Interesting read. Since I didn't see any reference to moving the vat I assume they are just lifting the z axis and letting the fep membrane pull off. They talk about the membrane being permeable to a gas/liquid which inhibits resin cure so it shouldn't stick. The slight flex to the membrane must be enough to pull away at the edges. By eliminating the tilt they effectively speed up the printing.

Since there is a gap I wonder how they keep the membrane from sagging under the weight of the resin. Unless they fill it with a liquid to support it.

Thinking about that, I came up with this idea for a vat that uses a liquid supported membrane and a piston to draw it down away from the cured resin. The build platform only has to be raised up the layer thickness and the membrane returned to neutral. Backlash in the z axis is eliminated because movement is only in one direction (up).

[hp_]

they pump air between the cap and keep a pressurized gap (1 atmosphere pressure i think)

[AndersonTa]

FEP is an oxygen permeable membrane. Solidator uses a pocket of air between the FEP film and the glass window of the vat bottom, that pocket of air has a constant air flow from a compressor. No pressure build up, just constant air flow. Since FEP is oxygen permeable, air can pass through the membrane and negate any vacuum forces that occur. You can't form a vacuum if the surface is actually porous and having air flow through it.

Does that make sense?

[Phife]

FEP is an oxygen permeable membrane. Solidator uses a pocket of air between the FEP film and the glass window of the vat bottom, that pocket of air has a constant air flow from a compressor. No pressure build up, just constant air flow. Since FEP is oxygen permeable, air can pass through the membrane and negate any vacuum forces that occur. You can't form a vacuum if the surface is actually porous and having air flow through it.

Does that make sense?

It doesnt really make sense to me, If the FEP can allow air through to relieve the vacuum pressure wouldnt that create bubbles in the resin?

If they are putting air into the gap but allowing it to flow out so no pressure builds wouldnt that cause ripples or waves as the air flows between the thin film and the vat bottom?

Also, if there is no pressure in the gap between the vat bottom and the FEP film how does the FEP remain flat?

I like that they are apparantly using the oxygen permeability of the FEP to create an oxygen inhibition layer so the resin doesnt stick to the vat bottom, and allowing air into the gap would replenish that oxygen constantly.

If we can figure out how they get it to work exactly that would be great, but so far I like 258cj7's idea with the water and piston to deform the film, I might try something similar since my machine has such a large build area.

[HTL]

just speculation but I suspect what may be happening is that the fep actually lightly lays on the vat floor because the air pressure under it is only slightly above ambient air pressure and is held down by the weight of the resin, when the vat tilts (if that's their method) or the build plate lifts the fep "membrane" lifts very slightly under light air pressure and allows air under it, some of this air "diffuses" basically atom by atom through the fep with enough oxygen to "refresh the oxygen layer on the top surface of the fep (it probably doesn't take much). The oxygen on the top layer of the fep probably refreshes the "hydrophobic" properties of the fep rather than actually breaking the vacuum. Oxygen would constantly be diffusing through the fep with a "push" every layer cycle.

[Phife]

Could this be made to work with a fluid instead of air? would something like water or some other fluid be able to carry and release enough oxygen through the film to allow the oxygen inhibition layer to form?

Maybe when the layer is printing the film is resting against the vat bottom and when the part raises the fluid is pumped in and the film raises off the vat bottom and then the fluid is pulled back out.

What do you guys think?