Pinholes in infused part HELP!

Talk Composites - The Forum for Advanced Composites

Back

Pinholes in infused part HELP!

Author	Message
Xtreme	X Xtreme posted 4 Years Ago HOT Post Details
X Group: Forum Members Posts: 4, Visits: 10	Finally managed to do the infusion yesterday. Setup done as per guidance by Mark. It turned out fantastic! No bridging No pinholes on the first impression. I have noticed pinholes get prominent ones you spray 2k clear. Will be spraying clear coat and give you guys the update. But really happy with the outcome. Thank you Mark !
	Reply Like 2
DD-Compound	DD-Compound posted 4 Years Ago HOT Post Details
Group: Forum Members Posts: 25, Visits: 1.1K	+x MarkMK - 7/14/2020 11:35:24 AM I've tried MTI hose and found it to be an unnecessary expense and not needed where just a refinement of basic approaches is all that's required. It's been covered many times before, with a variety of opinions, but after de-gassinng the resin for quite a period I've found no discernible benefit to adding-in this step. I'm doing infusions every day and even where the resin is quite freshly mixed and showing visible bubbles, there is no visible effect on the finished part, as the resin will de-gas as it's drawn through the part and anything left in the resin at the end will shrink to virtually nothing once the vacuum level equalises across the part. There will still be gas drawn out, even after a prolonged period of de-gassing and weighed against the reduced pot-life time, it's not a step that I've found to be necessary in achieving perfect cosmetic results. I don't think that either is the answer to the OP's current issues where it feels like some tweaking of approach will be all that's needed. Thats a brave comment. Physically it is not true what you say. Yes you have a degassing in the flow media during infusion. But not 100%. So some air will travel in the fibers and will stay there. You won't degass anything if the resin is not moving as the air will not move because of friction and surface tension in the fibers. If you have a degassed resin there is less air, true you can't get it 100% free of air but lets say 90% less air. And thats already 90% less that can go into your laminate. You are correct with what you say that the "bubbles" shrink to virtually nothing once the part is filled. But thats because the pressure is leveled to ambient in the part after infusion because the resin is pushed in by ambient pressure against the brake zone. BUT once you clamp the feedline you still have the vacuum working on the spiral. And the brake zone is called brake zone because it slows the resin. That means that it just takes a while til the minimized airbubbles will start raising again because they want to expand and push resin into the spiral hose. And that's what the MTI hose is made for. It is a resin stop, so the resin can't travel anywhere and the laminate will not be affected by the vacuum. and the airbubbles keep as small as they would be at ambient pressure. Also the MTI hose allows to infuse independent of the flow front. If you think it's wasted money thats ok, and yes in an ideal world infusions can be good without degassing and MTI hose, but it helps and brings process stability.
	Reply Like 4
Lester Populaire	L Lester Populaire posted 4 Years Ago HOT Post Details
L Group: Forum Members Posts: 311, Visits: 13K	Just so everyone knows... DD compound is the manufacturer of the MTI hose that they praise here...
	Reply Like 3
Hanaldo	Hanaldo posted 4 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	+x Lester Populaire - 8/12/2020 3:08:17 PM Just so everyone knows... DD compound is the manufacturer of the MTI hose that they praise here... You say that like it's a bad thing. Dominik stands by his product, and so he should - it is a great product, there's nothing wrong with it. He also knows a lot about infusion, and I don't doubt at all that what he says is theoretically correct. That said, and with all due respect to Dominik - I disagree that degassing is necessary, and I personally believe MTI Hose to be unnecessary as well. I would however absolutely recommend MTI Hose for beginners, it can really make the process simpler and more forgiving. I used to use it a lot, and I'll admit at the time I thought it was the bees knees and I got instant great results with it. These days, with more experience, I get those same results without the hose - hence it is not necessary to the process. For me, it became a high cost luxury product that wasn't really doing anything for me, and so I stopped using it. But if you are a hobbyist wanting perfect results and you're more concerned about the cost of wasting materials in a failed infusion than you are about paying a few extra $$$ for the hose, then it will probably help you. Degassing - I find it causes more problems than it solves. As I said, theoretically I feel I agree with Dominik's understanding of the physics. It makes sense to degas the resin and further reduce the amount of air included in the infusion process. In reality though, I feel it just complicates the process. Not all resins are equal, some take longer to degas than others, and the whole time you are messing about with that your pot-life is ticking. All well and good if you are infusing a small component with 500g of resin and it will be done in 2 minutes, and it all fits nicely in a degassing chamber in one batch, but try messing about with degassing when you are infusing 15-20kg of resin. And considering I can get flawless pinhole free results without degassing, I again question it's necessity. End of the day, there's a lot of ways to skin a cat. Lots of people will find they get better results when they degas, lots of people will find they get better results when they use MTI hose, and power to them. We're all just trying to get perfect results, so whatever works for you is great. I offer my advice from my perspective, Mark can offer advice from his perspective, Dominik can offer his advice from his perspective, and hopefully between us we help some people nail an infusion!
	Reply Like 4
Lester Populaire	L Lester Populaire posted 4 Years Ago HOT Post Details
L Group: Forum Members Posts: 311, Visits: 13K	+x Hanaldo - 8/13/2020 2:08:51 AM +x Lester Populaire - 8/12/2020 3:08:17 PM Just so everyone knows... DD compound is the manufacturer of the MTI hose that they praise here... You say that like it's a bad thing. Dominik stands by his product, and so he should - it is a great product, there's nothing wrong with it. He also knows a lot about infusion, and I don't doubt at all that what he says is theoretically correct. That said, and with all due respect to Dominik - I disagree that degassing is necessary, and I personally believe MTI Hose to be unnecessary as well. I would however absolutely recommend MTI Hose for beginners, it can really make the process simpler and more forgiving. I used to use it a lot, and I'll admit at the time I thought it was the bees knees and I got instant great results with it. These days, with more experience, I get those same results without the hose - hence it is not necessary to the process. For me, it became a high cost luxury product that wasn't really doing anything for me, and so I stopped using it. But if you are a hobbyist wanting perfect results and you're more concerned about the cost of wasting materials in a failed infusion than you are about paying a few extra $$$ for the hose, then it will probably help you. Degassing - I find it causes more problems than it solves. As I said, theoretically I feel I agree with Dominik's understanding of the physics. It makes sense to degas the resin and further reduce the amount of air included in the infusion process. In reality though, I feel it just complicates the process. Not all resins are equal, some take longer to degas than others, and the whole time you are messing about with that your pot-life is ticking. All well and good if you are infusing a small component with 500g of resin and it will be done in 2 minutes, and it all fits nicely in a degassing chamber in one batch, but try messing about with degassing when you are infusing 15-20kg of resin. And considering I can get flawless pinhole free results without degassing, I again question it's necessity. End of the day, there's a lot of ways to skin a cat. Lots of people will find they get better results when they degas, lots of people will find they get better results when they use MTI hose, and power to them. We're all just trying to get perfect results, so whatever works for you is great. I offer my advice from my perspective, Mark can offer advice from his perspective, Dominik can offer his advice from his perspective, and hopefully between us we help some people nail an infusion! I really like the MTI hose and we always have some in stock in the workshop. It can help a lot with complex shapes and moulds with a very small flange or things like that. back in the days i used it for pretty much everything and as you mentionned now it's more for special cases. However i feel like degassing does help a lot depending on the fabric stack and flow rate it might be more or less important. We have it integrated in our workflow where it doesn't affect us too much and it is just nice for peace of mind where we know that this is one factor that we control and won't bite us. i just think it is a little sleazy when the marketing department is praising there own product in an internet forum without stating how they are involved.
	Reply Like 3
DD-Compound	DD-Compound posted 4 Years Ago HOT Post Details
Group: Forum Members Posts: 25, Visits: 1.1K	I thought that the DD Compound in my signature is big enough 🤔 Also wrote several times here that DD-Compound is the producer. I also agree to Hanaldo that the MTI hose is not a must. But the people how have enough knowledge and work on their own who get good results without tips and tricks is maybe 5%? People who start or productions that need process stability are most of the composite users. And also Hanaldo started one day and made his first successful infusions with my help and MTI 😉. I am proud that he got that much knowledge and understood the process that he knows when he has to do what is necessary. When to degass and when not, using MTI or not, maybe reduce vacuum or not...... As simple as it is it is quite complex at the end of the day. I am not making any money from smaller customers, usually we send also nice samples to all over the world to help beginners. My reason to spread knowledge and help do more People understand the physics. In the infusion industry is so much wrong information going around and also lots of „experts“ have no Clou what they do. The tips I give here are to help people, and if they are followed you will get a perfect result. I think it does not help if people just say this and that is not necessary but don’t explain why or just give that info for the special case. I want to give people a toolbox so they are successful and understand the process. If they do that for a while they will understand more and more when what to do and of course if they are a pro they don’t need everything. But you will see that if you for example have a big production things are more focused on process stability than on saving in materials. I do infusions from 100g to 6tons of resin, the physics is the same but lots of parameters change. To much to explain everything so I always try to explain a process that works for 90%.
	Reply Like 3