My Infusion Adventure - Pics and Videos - Looking for Advise :)

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#1

I have been trying for a while now to complete an infusion with a perfect part, but have had all sorts of issues. Its been a real learning experience. I have gotten a lot of help so far and wanted to post my latest adventure and hopefully get some more assistance. My initial plan was to infuse two molds at one time.

I have tried to document everything with pictures and videos. I will post pictures of the finished part tomorrow. Fingers crossed.

First I waxed both molds.

My plan was to try and envelope bag the parts because I have had such a hard time getting a perfect vacuum on my molds. I went through and covered both molds with material to ensure no sharp edges damaged the vacuum bagging.

I then made both vacuum bags.

I then put two layers of PVA on the molds and laid the material. I put 3 layers of carbon fiber on each mold, then peel ply, then breather material. I put a small probe in the center of each part where I will attach the resin inlet tube.

I decided to try and wrap a vacuum tube around the entire part. I added small holes to the tubing and then attached to each mold.

I bagged both molds and then attached the vacuum lines.

This is where I ran into my first issue. The first mold started cracking and falling in on itself. I had to abort the infusion as the mold was basically destroyed by the vacuum.

#2

I originally wanted to try envelope bagging because of all the trouble I have had getting a perfect vacuum, but after destroying the first mold I decided to go back to bagging on the mold flange. I attached a vacuum bag and pulled a vacuum but could not get a perfect seal. I have never been able to get a perfect seal on this mold for some reason.

My next step was to double bag, but I couldn’t envelope bag because I was afraid the mold would break. So I decided to just add a second bag on the mold flange. I didn’t leave a lot of room so I trimmed and pushed the first bag back to make room. I was able to pull a perfect vacuum on the second bag. I mixed and then degassed the resin. I am using Adtech 820 with 823 hardener.

#3

I then started to infuse the part.

http://youtu.be/ydKrGy_EXDU

The only issue I noticed was that the resin seemed to flow really fast, but I let it infuse for about 5 minutes until the resin was almost gone. One corner seemed to have a hard time removing any air. After about 20 minutes there was no more air that I could see.

http://youtu.be/Euh3llyJ-m0

I clamped the resin line and took a quick video. I will leave the vacuum running all night. Sorry about the dogs barking in the background…

http://youtu.be/0Ew7YW_55L0

So that is where I am at now. I am hoping to have 1 good part tomorrow but I don’t know. Any advise would be great. I have invested a lot of time and money so far trying to get a perfect part. I think I am really close. Thanks in advance for any advise!

Daniel

#4

As to why your mold failed when you envelope bagged, I can offer some advice there. You have to think about how atmospheric pressure works on an object. Think of it in terms of exerting 15 lbs on every square inch of surface area of an object. When your mold is sitting there by itself, there is atmospheric pressure exerting forces all over the mold, on both sides, The force on the top and bottom of the mold is equal, and there it no deflection.

In the video it looks like you boxxed in your mold (even the bottom). When you enveloped bagged, you took away atmospheric pressure all around the mold. However right outside the bag there is atmospheric pressure forcing on the bag, so you have force on the top of the mold. However, since you boxxed in your mold, the atmospheric pressure was forcing on your wood structure, NOT supporting the bottom of your mold. That is why it deflected like that.

You can envelope bag your molds but you need to do one of two things.

  1. Make your mold rigid and strong enough to support 14.7 lbs/in. On big parts, the forces get very large.
  2. Don’t box in the bottom of the mold. Allow the envelope bag to touch the bottom surface of the mold. Don’t let it bridge either. Give the bottom the same no bridging attention as the top side. This will give your mold support from the back side. If you do this, your mold won’t even know you’re pulling a vacuum, and will sit there w/o deflection.
#5

That makes sense Kevin. Thank you, I was pulling 30 inches too… No wonder it broke :).

#6

Yeah. If your mold was 12x12 thats approx 2115 lbs in the surface of that mold.

#7

Here are pics of the finished part. I am getting the same results as I have in the past. I am almost convinced that there are leaks in my mold and in the other molds I have made. I always get voids in the same spot and I am guessing that air is coming in from underneath the mold.

The second video I posted above shows air that formed and sure enough the voids in the part in the exact area. I was looking closely at the mold and I think I see a crack in the corner.

The only mold I have made that I can pull a perfect vacuum on is the mold that was screwed up from the envelope bagging above. I brushed the surface coat on very thick and then reinforced the back with a lot of extra resin I had by mistake. So that mold was sealed very well and I think that explains why I have had such good luck with it.

Here are the pics I am referring too. Thank for any advise.

#8

So continuing this adventure… I thought I had destroyed the first mold after putting it in an envelope bag. It turns out the mold just broke away from the wood frame. I went through and cut it away and thought I would try envelope bagging again and then infusing.

I wrapped the back of the mold in order to protect the vacuum bag. I turned on my pump and was able to get a perfect vacuum. Here is a picture.

I then unclamped the resin line and started to infuse. The part infused and I let the pump continue to run. I clamped the resin inlet tube and left the pump on. I went to check on the part about 20 minutes later and realized that I never unclamped the vacuum line. The part infused fine, so I unclamped the line and let any excess resin flow into my catch pot. I imagine the part infused fine because there was a perfect vacuum already. But I will let the vacuum run all night and check on the part tomorrow. Ill post pictures tomorrow. Here is a picture of the mold/part after infusion.

#9

Yesterday I did the same element as your


#10

Looks good! I should have a part like this really soon. I am in the process now of making a new stronger mold.

You part looks great, did you notice anything I am doing incorrectly?

#11

For me, no, not really. Waht you could try is infusing from one side to another, instead from the middle outwards, which can be awkward with small products.

My concern is the porosity of the mould you mention. You could cover the mould with bleeder or anything, pull a (light) vacuum, then paint the backside of the mould with epoxy.

#12

That is a really good idea, I am in the process of making a few more molds and have a very thick layer of epoxy and fiberglass on the back of each. If I come across any other issues with molds not holding a vacuum I will try the option you mentioned.

#13

For those of you following. I pulled the part today and it was perfect other than pin holes. I degassed the resin for 5 minutes and even tried to slow the flow or resin by clamping the inlet line. I had infusion mesh on the entire part (very small part) and the resin flowed through the part VERY fast. I think I need to slow it down but am not sure how besides clamping the line even more or maybe degassing for even longer.

I degas by putting the mixed resin in a vacuum chamber for 5 minutes. Should I leave it longer, or is there another process?

#14

I don’t have experience with how long an infusion should take, but if you want to slow it down, you can always clamp the line down more. Before you open the clamp to allow resin to flow, where is the location of the clamp on the tube/hose? It should be very close to the end of the hose. That way there is minimal air inside the hose and you reduce the amount of air allowed to be sucked in.

#15

Yup, I have the hose clamped very close to the resin cup. I am going to try clamping the hose even more then I do now.

#16

Like Herman said infusing across could help with such a small part. I was thinking maybe use less flow media for a larger brake area or maybe even no flow media. If your mould is air tight and the resin is degassed I would think your just flowing to fast.

#17

haa, how many damn times I have forgotten to open the vacuum line after infusing…No need to open the resin line again, just the vacuum, and let it draw out any extra resin :slight_smile:

#18

trim 1/4" of infusion media around the part, and I guess, clamp the resin line even more? Your video infusion speed looked ok actually. It is a tiny part after all.
When degassing, pull the vacuum, you will see the resin start to foam up. When the foam drops down and starts to boil you are done. If you have long gel-time resin, you can always just let it sit there boiling for 5-10min.

#19

I am VERY happy to finally announce that I pulled a perfect part today! Thank you very much to everyone who has helped me through all my issues so far.

I am now 100% sold on MTI hose! I have had countless issues with voids in parts and pinholes. Thanks to DDCompound for sending me a sample of the MTI hose. The first time I used it I pulled a perfect part. I will be placing an order for more today if possible!

Here are some pictures of the part right out of the mold. I will trim it tonight and post pictures in the Showcase forum.

Again, thanks to everyone for the help! I am sure I will have more questions, but this is a huge first step!

#20

That looks very nice. Congrats on your first part. I’ve been watching your threads trying to learn from everything I can from your issues. Did you change anything else in your process other than just using the MTI hose?