Vacvuum infusion F U # 2

Good grief Jimbo, seems you'll have to use that stuff in shifts by the sound of it.

The stuff I'm getting is said to have a pot life of 45 mins when hot and an hour if less hot.

 

As I said, you can kick it up with a 'hot' curing agent like TETA. Teta gels a 100gm mass in about 20 min @25C, so you have from between 1 week..................................................and 25 minutes as the range possible by changing the mix up. With higher heat, like 160-180F it cures in two hours with EMI as the sole curing agent. It think the ideal would be about 2.5% EMI and 1% TETA which could get you very long room temp pot life (prob'ly more than 4 hours) and good cure time, especially with some heat applied. Many people ar afraid to experiment, and feel they are 'stuck' with whatever curing agent came with the epoxy they bought. But it's OK to experiment with these test layups and find just the right mix for your project. That's exactly what I did.

Jimbo

 

Not at all; remember the thread about my first infusion experiment a week or so ago - I had 3 strips in one go, 2 with different "hole size" peel ply and one without - speed of infusion was about identical for all three types.

 

So when you open the resin inlet the vac drops? I don't think my tests ever did that. I spent a lot of time ensuring a perfect seal on the layup before I opened the resin inlet. I could shut off the vacuum and it'd hold for at least 10-15 mins before I saw a loss of seal. I know this because I setup the pump to run automatically when vacuum drops. I also plumbed in a vacuum reservoir made out of some PVC pipe and caps. See the pic I posted earlier, it's the black pipe standing along the back wall.

The shade cloth you used looks like it worked well. I'm trying to find some of that here because the flow media is obscenely expensive.

So I guess all I can offer now is to ensure you have a perfect seal on the layup before you open the resin inlet. Pull it down to full vacuum then let it sit for 10-15 mins to see if it looses it's seal. If it does, you have to find the leak and seal it. If it holds then the layup should be good to infuse. I think you said you're at 3500 m above sea level? Wow! I'm less than 100. That might have something to do with it too.

Good luck.

 

Hi guys,

I got the new resin this morning. Had a brief chat with someone else on the infusion process as well.

The first factor that slows the process is the thickness of the layup. 8 layers can be done but aparently it will cause the flow to slow down much more than 4 layers.

The viscosity of the resin, of course.

It is in the thirties here, even the glass is hot to the touch, and waiting till dawn doesn't make much of a difference either. I'm not going to wait until winter to do these beams.... instead I'm going to try a different approach by using say 3 vac outlets and say two supplies, and the second pump gets a syringe needle I can vacuum a stubborn area if need be.

Rick, the vac doesn't drop once flow started, but without the resin it drops when it sucks air in. I do check for leaks multiple times. I have a very slow leak on the resin trap which I'm going to have a look at this afternoon.

Anyway, the new thin resin and it's longer cure time should maybe make the biggest difference. It's just bloody expensive.

 

Hey Fanie

Don't give up. You'll figure it out! I luv experimenting with this stuff.

There's another way to make tubes and beams that doesn't involve infusion. You can try various knitted socks & shrink wrap. I'm doing my shaft log this way as the infusion tests were a horrendous failure!

http://sollercomposites.com/composites/carbon fiber sleeves.html

There's a brief tutorial on the bottom of the page. I think this would work for a square beam as well as round shafts.

 

Hi Fanie
I can not tell for sure from your picture but I think yourproblem is the vacuum line.
For a set up like in your photo where you have a lon resin feed line you should have a vacuum line that is a mirror image, ie full length of the beam on the oposite side. Also would be better to have your resin inlet along the centre of the feed line. For the vaccum line (vacuum spiral) also would be better to attach the vacuum at both ends.
The other thing that does not make sense to me is when you say that the vacuum drops when the resin inlet is opened, can you explain exactly what you are doing when this hapens.
You are not opening it without having the resin inlet tube imersed in the resin are you?
Its late here now, I will give you are few more suggestions tomorrow.
Cheers
Andrew

 

Hi Andrew,

Under full vacuum and before the resin I open the inlet to see if there is decent air flow. There is no resin at this stage.

Well, first beam infused. It just started gelling now.

The tech guy at NCS said I could try to start up by not having full vac when I opened up. He said the glass may be more restrictive then so I tried it.

The resin I got is red, it looks like the decent super petrol you got in the old days. It's not like water, but it flows easier than the grp I used before.

How does under a minute sounds to you ? When I switched the pump on and the bag started clampin at about 20kPa I opened the resin. I couldn't believe my eyes. Under 1 minute ok. This stuff flows it's scary.

I have used two outlets and one inlet. This won't be nessesary and one inlet and one outlet is going to be more than sufficient, same as I had before.


Thanks to all who helped, supported, advised, gritted their teeth, Manie who worried I think from here on it's going to be a wee-wee.

 

Hi post some pics when you get time

interesting - are you saying that the NCS people can actually solve a problem?? not like flippen "harveys=idiots"

glad to hear that you are coming right

 

Hey Fanie Im glad NCS could help.I have not had any thing but good service from them.Harveys who's Harveys sounds like some dodgy hamburger joint

 

Just goes to show ya, those specialty infusion resins really are special. As much as we'd like to be able to use the regular stuff it just ain't up to the job. Good work Fanie!

 

Eh eh eh you guys, don't try and get away so fast eh !! Who's going to do the other 3 beams ?

 

In the past I always got good service from Harvey's. The new rep was here once and the guy had one too many. Since about then I got virtually no service from them so maybe they have a problem. Dunno what's going on there, but I don't want to wait a week and several calls later and no response.

There wasn't time to take pictures while the process started, I frantically trying to line everything up and looking for the vice grip to clamp supply off. It was over quickly, a bit of a surprize really.

The beam beings sucked like... a what's that called again Wynand

The beam stripped outside on the boat (my only work table for now) Turned into carbon fiber before my eyes

Peel ply gets stripped off... some inconsistency on the corner there. Don't know how one can wind the glass tighter.

The peelply as it came out, still smelly but is dry to the touch unlike the resin I used before. Doesn't look like much excess resin there.

The excess resin. I calculated 1.7 liter of resin required, but wasn't sure how much will be taken up by the spiral and shade cloth, so I got 2 liter. I's say it came out pretty close.... glass was 2m x 1.3m x 3off at 450g = 3.5kg glass. 50% resin is 1.7kg or about 1.7 liter.

That is what came out of the resin trap. Maybe the wife can use it to put a pot on or something I know it's not supposed to end up in the hoses, but it was over before I realized it.

 

I must say that during the infusion process I hardly smelled any resin, despite that I worked in the workshop.

The newly infused beam has a very faint smell to it and I've placed it in the sun, two hours or so and it should be fully cured.

There is so little resin in it it almost looks dry, the usual gloss you would get with hand layup is not there.

 

Fanie,

Good to see that you are happy with your latest effort.
Here’s my opinion on some of the earlier comments made.

Infused laminate resin content is half that of open laminate therefore infusion process will save me money; WRONG. In most cases Vacuum infusion will cost you more in both time and consumables compared to open laminating. See for your self use the spreadsheet I have previously posted, I will attach it again as I have added some of my trial work I did for determining flow times and wet out rates for some common resin transfer media and thin laminates.

So why use the infusion process, for me main reasons are 1. quality of the laminate, 2. reduced weight when used with thin laminates and cores, 3. ability to laminate large structures in one hit on your own, 4. reduced exposure to resin.

Negatives; 1. increased cost, 2. reduced ability in laying down reinforcements so that the fibers remain straight which leads to crimping of the fibers. You have already experienced this for your self with your beam where the glass has been crimped along some of the edges.

I am building a 12m foam/glass/epoxy catamaran and like the benefits infusion offers. But this does not mean I infuse everything, I still hand laminate and vacuum bag also. I used infusion for the outer hull laminates, to make the rear and main connecting beams and all rectangular flat panels for bunk tops, floors etc.
Irregular shapes with cutouts such as hull bulkheads I hand lay and vacuum bag, also critical components such as composite chain plates.

I also encourage you to do similar for your 10m foam catamaran.
But also strongly recommend that you do more upfront trial work with the materials you plan to use before you start. I thought you jumped the gun with your beam.
Make some test pieces like Wynand is doing and make sure you document all of this. Get Wynand to forward you the emails I sent him recently if he still has them.

Thin laminates are very easy to do compared to thick solid glass ones.
Your beam laminate is not thick, vacuum infusion is used for making huge wind turbine blades with solid 30mm thick sections.

To optimize for solid laminate infusion you need:-
1.low viscosity resin <200cP@25’C (mPaS is the same)
2.long gel time, hours not minutes
3.select open reinforcements (gaps between the yarns) not all fabrics are the same
4.when making components such as chain plates or beam flanges with lots of UD glass make sure there is sufficient DB interlayerd so that there are enough open channels in the z direction through the stack.
5.in very thick laminates when DB alone is not enough you may have to incorporate CFM (continuous filament mat) or infusion grade Lantor core mat or even embedded plastic infusion medium such as Enkafusion.


More specific to your beam; should you use a faster shade cloth? No I don’t think so, if the medium is too fast resin will skip across the top and reach the vacuum lines before it penetrates the stack.

After pulling the vacuum down and making sure there are no leaks, why do you want to open the resin line and introduce air into the system?
In extreme cases people wanting perfect components will use as close as to 100% vacuum that’s possible and will de gas the resin to get rid of entrapped and dissolved gases bore the resin is introduced.

Although you say you are happy with your last result, I do not think starting the infusion with very little vacuum at first makes a good system. Personally I would be doing everything else possible before resorting to that.

Trying to form the laminate around the foam core without some crimping is very hard to do. So what is better, infused beam where the bulk of the laminate is extremely good but has some crimping of the reinforcement. OR A hand laminate that is nowhere as good but has no crimping?
Can anyone answer this? as I am still to build my forebeam and at the moment I am leaning towards building in two sections to ensure there is no crimping and taping together.

Also have attached some photos showing some of the trial work determining the flow rate data for the media in the spreadsheet.

07163457; comparing 30% SC, 50%SC and Delstar #14610
25151039; top is Aerovac, Airtech greenflow and bottom is Airtech resinflow

21084617; 260 x 340mm solid glass laminate (my main connecting beam flange laminate schedule, 24 x 450g UD + 4 x 450g DB glass)

21084925; same test piece looking from underneath (infused on a glass sheet)
Centre time markings 1-13min show a slow but fairly consistent wet out rate, in contrast with the resin flow across the top which is fast at first and progressively slows down shown by the bottom markings.

Cheers
Andrew