New to infusion and need alittle help


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dcfoster
dcfoster
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Ok, so Vacuum bagging is where I would basically 'soak' the carbon fiber, place it into the mold, then bag it and put vacuum. Infusion is where I put the dry fiber and bagging materials in, pull out all the air, then draw in resin?

...Would explain my confusion, most people I talk to refer to Infusion and 'vacuum bagging' as the same thing...or maybe im just not paying attention (which could very well be).

So if I lets say laid out the fiber, painted on the resin then put it in the mold and added the bag, connect to vacuum, that is what this Dura-Klear Laminating resin is for. My only concern is having enough time to get all the layers wetted up then put in the mold then whatever materials on top and sealed down before it starts to harden. Im gonna go look up 'Vacuum bagging' to see if that is a better choice for me for this week until I have more time to source an 'infusion' type epoxy. Unless the solution that Hanaldo gave me will suffice for now (feeding and drawing from 1 side of the mold to the other and not end to end) The west system epoxy I know will work for the bagging method because with the ultra clear hardener it seemed to have a longer pot life than the epoxy im using now.

Lastly, if I need to fix the mold, can I add some tooling gelcoat to the imperfection, let it cure and then sand it smooth? or will that pull away from the surface thats already there? I know I will need to clean the release wax Ive been using.
Edited 10 Years Ago by dcfoster
ChrisR
ChrisR
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just so you know (picked it up from one of your posts), "vac bagging" and "infusion" are two completely different methods, vac bagging you laminate (wet lay) then put into the bag and pull the vacuum - so they may have confused what you want to do with it. Infusion is still quite a new concept in a lot of circles.

From what I know, West Epoxy do not do an infusion resin. I use Huntsman LY1564 with 3487 or 3498 (I can't remember at the moment) for infusion, viscosity is 250ish mPa s @ 25deg and is a specific infusion resin with a couple of hour pot life. Even wet lay I use one with a 2-3hr pot life, it just saves f-ing a round knowing you're going to run out of time!
dcfoster
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ChrisR (12/05/2015)
A quick search suggests this is a standard laminating resin and a fast hardener, it will not have a low enough viscosity to flow correctly through the part, you may get better results by heating the resin up a touch to 25/30deg C (search on here for method) but check the data sheet. A "proper" infusion resin will have a viscosity in the low hundreds (100-300 mPa s) at 25deg C 

I've infused 1m before with success and it only took a few minutes, with 3 plys your infusion should take 5min at the absolute most 


ChrisR, so I need a different hardener or both epoxy and hardener. That sucks if it's not an epoxy used for vacuum infusion, the folks at Revchem Composites swear by it. I wonder if the west systems epoxy would be better as I need to redo and have the part finished by this weekend for an auto show otherwise my car isn't going
ChrisR
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A quick search suggests this is a standard laminating resin and a fast hardener, it will not have a low enough viscosity to flow correctly through the part, you may get better results by heating the resin up a touch to 25/30deg C (search on here for method) but check the data sheet. A "proper" infusion resin will have a viscosity in the low hundreds (100-300 mPa s) at 25deg C 

I've infused 1m before with success and it only took a few minutes, with 3 plys your infusion should take 5min at the absolute most 



dcfoster (12/05/2015)
Ok that makes more sense. However what did you mean by bridging?

The Epoxy im using is Dura-klear 80LS-19A laminating resin, the Hardener is 80LS-20B Laminating Hardener.

Curious, I know you say that by running the spiral line across the long side of the part it will travel the shortest distance, but its still covering the same surface area. shorter but wider, Im assuming the spiral feed line creating more places for the resin to flow from helps the ambient pressure push the resin because its not a long 'hallway' but a short wide one.

Hanaldo
Hanaldo
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Yeh it isn't necessary to know the science in depth to get good results, but I find once you understand these things you can predict problems and take measures to increase your chances of success. All comes with experience though, so you'll get there! 

The formula I use to determine bag size is:

((Depth x 2) + length + width) x 1.25

So twice the depth plus the length plus the width of the mould, plus an additional 25%. Works every time. You still need to go around and make sure that the bag is pushing the carbon into place everywhere though! Definitely possibly to have plenty of bag and still have bridging. 
dcfoster
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Ok, thats what I figured you meant by bridging. That seems likely to be happening, its difficult to get the bag to suck down into the gauge pod dip in the mold. I think more bag and maybe better pleating will allow it to get down deeper and keep the carbon against the mold surface. Ive learned alot from your help thank you. I still am having alittle trouble with the 'science' of it but this helps me with figuring out a good balance in what im doing. I know for sure the next mold I make will have a larger flange area than the last 2 molds I made. 

Thanks again! 
Hanaldo
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Correct, same surface area. The spiral hose simply extends the flow front, it doesn't slow the resin at all. You could theoretically accomplish the same thing infusing the length of the part by running your spiral hose from the entry point to the exit point. This would mean that your resin reaches the end very quickly, but for one you will waste resin as the resin that has already reached the exit will flow out of the part again before the rest of the part has fully wet out. Secondly, infusing at this speed would likely create voids as it doesn't give the resin time to wet the material out evenly; and third you will likely end up with the spiral tube 'printing' through onto the surface of the part. 

So instead, you move the spiral hose off the part to the mould flange, and place the vacuum port on the opposite side, so the resin flows out the length of the part very quickly, but you don't run into issues with infusing too quickly as the resin still has to move across the width of the part. 



Bridging means the fabric isn't sitting against the mould surface, instead creating a 'bridge' between two points.  
dcfoster
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Ok that makes more sense. However what did you mean by bridging?

The Epoxy im using is Dura-klear 80LS-19A laminating resin, the Hardener is 80LS-20B Laminating Hardener.

Curious, I know you say that by running the spiral line across the long side of the part it will travel the shortest distance, but its still covering the same surface area. shorter but wider, Im assuming the spiral feed line creating more places for the resin to flow from helps the ambient pressure push the resin because its not a long 'hallway' but a short wide one.
Edited 10 Years Ago by dcfoster
Hanaldo
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Your analogy isn't totally correct, but it's sort of the same principal. It also isn't because of the size of your vacuum pump. It's a bit of a tricky thing to understand because you need to know how the physics of infusion work, but I'll try to explain it because it's quite useful to know. 

 The resin doesn't slow because it is bottle necked. Think about the size of the hose you are using as your feed line. The ID is much smaller than the part that you are infusing, and yet it can flow very quickly through the hose, correct? What is happening when you infuse is the ambient pressure of the atmosphere is higher than the pressure inside the bag, and so the resin actually gets PUSHED into the part by the weight of the atmosphere rather than pulled by the vacuum. 

This is important, because this is why you infuse the shortest distance. The more material you have between the entry and the exit points in the part, the more material the resin needs to be pushed through and naturally the slower it is going to flow. You can get around this problem when you need to do a larger part by using a slower hardener and increasing your pot life, or by doing as you described by introducing multiple feed lines across the part to make smaller sections. Easiest solution is to flow the resin the shortest distance. 

Does your resin use a catalyst or a hardener? Vinyl esters are modified epoxies, so I am just wondering if this is what they are referring to with vinyl epoxy. Not that it is an issue, just wondering. 

Scuff up will work. Needs to be clean though, so use a solvent of some sort rather than a tack cloth. Wax and grease remover will do. 

Imperfections are up to you. Filling them with wax will still leave a textured finish that you need to buff out, though may be easier than what is there currently. 


Voids often develop at deep sections of the mould and tight corners because any air moves there quickly and then gets trapped by the resin. Generally these are small voids though, unless you have a leak. If it is a big void, it is more likely bridging. 
Edited 10 Years Ago by Hanaldo
dcfoster
dcfoster
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Hanaldo, thank you very much for the info that helps me out ALOT! Though im confused regarding the draw regards length. Watching the video on EC's website the infusion video seems like that part is a fairly good size but they said it only takes a few minutes to pull that. Maybe its the pump I have? its a 3CFM dual stage pump by Pittsburg Automotive, their specs says they pull down to 22.5 microns. FYI my above post I added the materials im using (specific brand names) Only thing I dont have is the Epoxy, its sold by Revchem locally in the U.S. in a few states, I believe its a vinyl epoxy..they said its used for bagging.
  •  Can I add multiple resin draw points to a part if its too long. (ie: Resin pot>feed line#1>part>feed line#2>part>feedline#3>part>pump line>catch pot>pump) just so long as I make sure the resin will pass a certain point before I unclamp the next line.....or is that just crazy talk?
  • You said to use Acetone, but what if I just did a scuff up and used compressed air & a tack cloth to wipe off the dust before recoating? which leads me to getting rid of micro bubbles when I use an applicator, I know you use a heat gun but how long to you hit it with heat for?
  • My mold has a few little imperfections that I need to 'fill in' so the final part is smooth. Can I use clay or wax (do I need to wax or ez lease it?) or should I just let the resin fill in the imperfection and sand it out? (fyi these imperfections will be raised points on the part, though not by 'much')
  • Lastly, if I run into a large part in the future how do I get around the issue of too large an area for the pump? my above idea or a slower cure resin?
Thanks again all your help, this I feel will get me past this little hump I cant get over in my learning curve.

edit: I think I get what you were talking about regarding the draw distance being too long. If the part width that im pulling the resin into is smaller than the length of the part then im basically like trying to quickly fill up a 12x40 ft room with people only coming in 1 door on the 12 foot side, even though its the same amount of space overall if I instead let people into the room via the 40ft side I will have more entrance space and thus fill it faster with less work. So feed on 40inch side and exit on 40inch side should net me much better results. Now to figure out why I keep getting bubbles on the gauge pod part I molded into the pillar. it is a deep part of the mold so maybe there is a bubble pulled from somewhere and it just sits there, that or its because of the way I was pulling resin that started to 'thin out' the resin to create gaps in spots.

 
Edited 10 Years Ago by dcfoster
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