Thanks everyone! I’ll bag it tonight and give it a try!
it takes practice. trust me… try adding a brake. play with hose sizes. i make small parts so i dropped down to 1/4 inch resin lines and 3/8 -1/4 vacuum. i know the mistakes are expensive. but you will get better. i have made every mistake possible. i even had my sprinklers come on and hit my infusion.
i say leave the vacuum on. holes may develop AFTER the infusion. ask me how i know.
Hey guys, just an update. I infused a small part and it was almost perfect, I had a perfect vacuum so I thought I would try clamping off both ends and leaving the part over night. I demolded after 24 hours and some of the resin (small dots) stayed in the mold. Maybe I didn’t wait long enough. I was using the Easy Composites infusion resin, slow. Any thoughts?
As for this part, I starter to try another infusion but could not get a perfect vacuum and didn’t want to waste the materials again. I have ordered a leak tester and will try when it arrives on Monday or Tuesday. I have been pulling -30 vacuum on my part but spoke with someone who said they recommend only 19in of vacuum on carbon fiber parts. Thoughts?
I have also ordered some Adtech 820 resin with the 823 hardner so I am hoping that
it will help having a resin that doesn’t take as long to cure and is maybe better than the Easy Composites.
Thanks!
Epoxy is slow. Try heating it up slightly during or after infusion. 100F is enough to have the resin kick fast.
So I should take a heat gun to the mold after infusing? How long do I need to keep it on there? Won’t that just heat through or stretch out the vacuum bag?
You should let the vacuum stay on a little more after infusion to continue pulling the left over air bubbles in the resin thats infused.
You can use cheap electric blankats for heating the mould before and after infusion.
Why did you clamp your vac line? At least in the easy composite video you can see that it does not work well.
And more important than the viscosity of the resin is the work temperature!
Try double bagging, degas your resin and let the pump switched on.
There will be no airbubbles if everything is made correct.
[SIZE=3][FONT=Calibri]dp I think there is some good advice in this thread I would like to add that I think it would be worth your while to take a closer look at the resin system you are using. I would want to use a system which would give me to a strong cured part in under 5 hrs. Running a vacuum for 20hrs seems excessive and expensive for small parts.
Print out and compare data sheets looking at mixed viscosity and temperatures cure times strengths etc.
For an example of how dramatically temperature and harder choice can effect both viscosity and cure take a look at the below link for the epoxy Ampreg 26 system , I use this quiet a lot especially for hand wet layup and bagging its very flexible as you can also blend the hardeners . The beauty is when you add a little temperature and use the slow hardener it viscosity drops from being in the 1000s cp range to under 250cp at 30 degrees C with good to high TG values and gives better values than many labelled expensive infusion resins. An elevated cure at 80 degree C for 5 hrs will increase TGs and do away with the need to post cure. For small parts these temperatures are not hard to achieve with a little house insulation foam hot box and a fan/bar heater/ plugged into an easy and cheap thermostat plug. For small parts you don’t always need to go down the very expensive infusion resin route to get good results.
One of the things I have noticed with the slower curing resins is that they seem to be of a more corrosive nature which is not so good for your mould surfaces as the release agents are exposed to longer attack from the corrosive make up of such resins. Tailor your resin system to best suit your part.
Take a look at the Working Properties vs. Temperature chart in the link below.
http://www.gurit.com/files/documents/Ampreg_26_v11.pdf
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So today I finally got some additional supplies in, I decided to try the double bagging method as explained by DDCompound. The infusion took about 20 minutes on this part since I slowed down the flow of resin from the cup. Both bags seemed to have a very good seal and the leak detector couldn’t find anything. At this point I have the resin feed line clamped off and the vacuum is pulling. The pressure has been at -30 the entire time. I did notice air bubbles which I have seen in my last 3 tries but they seem to have stopped now that the vacuum has had a chance to run for 30-40 minutes. I guess we will see tomorrow if it worked.
That’s good the read DP knock on wood it turns out. Were the bubbles close to the flow front?
Well my 4th try turned up the exact same results even though I tried to double bag. It looks to me like the resin just keeps pulling because the vacuum is on and there must be air getting in while it cures. Here are some pictures, I am of course getting frustrated, but will try again :). I do think I am going to work on some smaller, simple pieces before coming back to this mold.
Any advise going forward would be great, but I think I need to focus on a perfect vacuum with small simple parts. I just wish the leak detector I bought could actually find a leak.
Thats a quit easy part, so don’t worry.
You used the double bag, so you can be sure that no ambient air moves into the part.
There are three other things:
- The resin was not degased, degasing the resin is very important. If not can cause pinholes in the radius!
- Your vacuum was not high enough, you should have a absolut pressure of 20mbar/0.6inhg to be sure that you have no dry pots or pinholes
- Your flow speed was still to fast.
Wait until the MTI hose arrived, Place the MTI hose around the part (blue line) and the resin inlet on the marked place (red X)
Double bag your part to be sure that yout mould is tight, evacuate the air out of both bags with a T connector. Possible leaks should not be so big that you do not reach a good vac level.
Degas your resin. Place it for 5 min in a vac chamber than switch the vacuum off and wait 10 min, than degas for another 5 min.
Use flow media over the hole part and start the infusion with normal speed, it will take about 1 min. If you have degased resin, a vac level of about 20mbar, the mould is tight and work with the MTI hose your part will be perfect, I promise.
Mery Christmas
I would just like to say Dominic seems to be a nice guy,I to have had these same problems when infusing,so I went back to what I no,I just wanted to no if the mesh would conform around the fixing point,or did you make cuts to the mesh on them points.
I believe that your resin is pooling because there is room to pool - the fabric is bridging the corner, it can be seen clearly on pic 3. Try to press the fabric in the corners using a plastic stick, only vacuum usually cannot eliminate bridging.
Can you take a video of your layup and infusion? It would be easier to find the problem that way.
I will take a video next time I set it up. I believe my issue is getting a perfect vacuum. can’t seem to get 100%, there is always a small leak which is little enough that a leak detector cannot find…