Hello everyone,
I am new to this forum but will be on here quite often as I am doing a lot of experimenting and part production in the near future. A quick background on my Composites experience is I Did a fair bit of both carbon fiber and glass layups while I was on my college’s Formula SAE team. I made seats, intake manifolds, bodywork, other support structures ect. All that I know was self taught through books and trial and error while i was in school. Now I’m out and working as an engineer at a mechanical contracting company in the Chicago IL, USA area but Composites is a passionate hobby of mine more specifically geared towards race cars which is my other passion.
Now that all that is out of the way I have plenty of questions and am looking for help. While I was laying up parts for the FSAE team we had minimal tools so all the components were either wet lay up or wet layup then vacuum bagged. Honestly none of the parts I have made never really gave a satisfactory surface finish and I would like to improve upon that.
I did a few basic wet layup vacuum bag pieces in my garage on a sheet of plate glass over the last few days and they have all ended up with that surface porosity on the glass side where you get tiny pinholes where the strands cross each other.
My materials are:
2x2 twill 5.7oz carbon fiber
standard peel ply mesh
2 layers of breather cloth
standard vac bag film
U.S. Composites Epoxy Resin with medium hardener
surface prepped with 2 coats paste wax buffed on and off by hand
Something I should mention that i noticed about the actual bag material is it is very stiff as in there is little stretch to it. The last bag system I used had plenty of stretch and would conform to just about any shape. Not sure if that effects anything.I went with a resin rich mix the first time and the breather was fully wetted out when under vac, the second run was about a 55:45 ratio by weight of carbon to epoxy. Both netted the same pinhole surface finish. It is my understanding from reading some of these posts that that is simply just what happens with a wet layup vacuum system and i will have to clear the parts and do a significant amount of polishing to get the surface finish right. I have also tried laying thick coat of resin on the glass first then laying the first layer of carbon down, and i tried the opposite of laying the carbon down first the applying resin. All cases end up with the same ugly surface. In the past I have tried degassing the resin and still the result was the same.
I am not sure if It is the resin or technique that I am using that is wrong but I would like to rectify it. I also plan to experiment with infusion in the near future. I am not opposed to buying and trying different things, I know that starting up and getting a process down costs money and time. If you can recommend other epoxy systems or good sites that offer infusion systems/ materials It would be appreciated. Preferred that they are in the USA. I have only used US composites as they were a sponsor of our FSAE team in the past and that all that I really know of at the moment.
My ultimate goal is to make structural composite components for drag racing applications but that is a long way away. I want to get the simple things down first like making a trunk lid or door consistently well with a good process. I have a long way to go but i figured all the expertise here could help show me how uninformed I actually am haha. Thanks for all the replies in advance.