Hi, just wondering does anyone has used this product:
http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1340/index.html
I would like to know if it can be used on a infusion process, right now we are using normal vacuum bags, but this looks interesting, could it work?
Best Regards,
Alejandro,
Anyone? with any background on infusion using this product?
Best Regards,
Alejandro
I don’t have experience but be patient on a reply. Pretty much everyone here is super busy at work so sometimes it takes a while to get a response!
Yes, siicone bags can be used for infusion. Smooth-on siicone is just like the other brands the you brush on or spray on. They are not as nice as the uncured siicone sheets that you autocave, but they do work assuming you make sure they are leak free. Make sure you use a reinforcement mesh that is made for silicone bags, this keeps in from tearing.
Hi, thank you for your comments, and where can I find the reinforcement mesh for silicon bags?
Alejandro,
airtech sells it, I think its called RVBmesh1
can you use it without the dove tail grooves?can you use regular bag tape with it?the stuff looks really interesting.i would love to have custom made bags for some of my high production parts.
they have videos on there site that show the construction of a bag using sealant tape.
cool.i watched the video of them making the boat hull bag.but i didnt see any other videos.ill take another look.
I used it, and made a few bag. Although tere are advantages, I do not feel that this stuff is used economically. Typical lifespan is perhaps 30-50 products, untill something goes catastrophically wrong. Given the amount of time and money spent on the silicone and producing the bag (do not forget you need to create a relatively accurate product by hand laminate or infusion in the mould as well, to allow for laminate thickness) I was not too happy about it.
At 8:14 in the video, it looks like there is a fabric/scrim texture embedded in the silicone (in the flange area). I don’t recall seeing that step for reinforcement. I would imagine having a large silicone “bag” like that, tearing could become a issue if the silicone is thin, and not handled carefully with 5+ technicians.
I made a similar silicone “bag” with the Freeman V-330 silicone (shore 25A)and Bluestar Thixo additive, to make it non sagging and brushable. One disadvantage is that the product is light blue and not transparent. It only takes like 2 drops of thixo in a 16oz batch of silicone to make it not sag. The flange of my test piece is about 4" wide, and smooth without any routed channel. I drilled a hole in the bottom of the mold and attached the vacuum port there,which worked 2x so far without any leaks. I really want to experiment with the infusion process, in combination with the silicone “bag”, it could be a real time saver.
I’ll have to keep a eye on this thread to see what you guys are working on in this area. Thanks for the tips.
i saw the video of them doing a hood bag.they used silicone tape around the edges.then some reinforcing fabric.then when you use the bag.you use tacky tape to stick the silicone tape on the bag to the tool.i am doing some parts where i will need to do secondary bonding.so these look really appealing.just not sure of the durability.i would hate to spend the time and money on it.then only get a few uses out of it.
The trick when you want to use sealant tape, is to apply a double sided tape on the mould flange, and, sticky side up, flash tape (this is kind of fidly). Now when you brush on liquid silicone, it will adhere to the flashtape. The flash tape gives the silicone bag a place for the sealant tape to get hold off. Sealant tape will not adhere to silicone bags! (due to the vacuum you might or might not get a good seal).
You can use silicone Omega shaped profiles to create a runner system in the bag. That is a nice thing. You can even elaborate further, and use half-hollow shapes on the outside. When pulling a vacuum in the half-hollow cavity, the bag will be pulled inside, creating a runner. After infusion, the hollow is brought back to athmospheric, so there will be no imprint or resin ridge. Anyhow, this all has been tried and tested. It works in a lab, but to roll it out on the production floor, is another thing.
Herman, you said you have to allow for the laminate thickness in the mold when you mold the bag. Is that right? If you’re doing less than 800gsm, wouldn’t the shrinkage of the silicone during cure allow enough thickness? I was wondering about breather fabric, too. If you have some bulk inside a concave part, do you run into trouble with the bag?
If so, does anybody have any quick tricks for modifying the mold to make the bag with allowances for the laminate and breather fabrics??
Yes, you need to account for the laminate thickness, and everything else you would like to stick in the mould before closing it with the silicone bag.
The shrinkage might allow for enough cavity but it is not really exact science, is it? I would like to depend on a bit of stretch in the bag to fill out the cavity.
You can use sheet wax to create an exact shape, or laminate a product very nicely, then sand it smooth, and tape it up with teflon tape (Airtech Teflease MG2)
I feel the Smooth-on silicone vacuum bag products are best suited for when you wish to duplicate an item . After creating the mold , you then leave in the original part while constructing the silicone vacuum bag . The weight of the silicone bag will help hold down tight corners , hard undercuts , and other areas where you’d normally need to add fillers and multiple layers of void filling fabrics . Depending on the application , incorporating the resin channels into the bag saves can time/money in the long run . Layout of the resin feeds and vacuum connection is the most important part of making your own bags like this . Incorrect placement of each and the infusion process will fight you every time . Enjoy .
We’ve done it, not a big fan to be honest, in lieu of this, since the steps are almost the same anyways, just make a positive tool and go LRTM. If you made your female mould than making a male version is the same. It will last as long as you want it to, the A & B side are finished in one shot, you still need the same set-up anyways. Difference is as oppose to producing a silicone “positive”, you are making a glass positive.
Just my 2 cents…