Carbon Fiber Intake Tube

General Composites Discussions Composites Talk
#1

Hi guys I’m new here and new to making my own composites! I am a third year Mechanical Engineering student in Canada. What I want to do is make some carbon fiber parts for my truck which include; Intake tube, Turbocharger tube, and Intercooler tubes to start.

I have began making my intake tube plug utilizing the following materials:
Foam - Floracraft Dry Foam from michaels craft store
Basic hot glue
Bondo Gold body filler
Filler primer
Duplicolor engine paint

I just received my prepreg carbon fiber from Composites Canada (196gsm and 670gsm) and I attached the spec sheet they sent me.

My plan was to make the mold from the prepreg as it will cost me the same as to do a wet layup fiberglass mold vs prepreg.

Do I need a gelcoat for a prepreg tooling mold?

My vacuum pump will only get about 17 inhg at sea level, will this be sufficient?

Will my plug hold up to curing the mold in an oven? I will need to make an oven, any suggestions?

Sorry about all the questions guys I have spent about 2 months researching and am getting really excited!

The pictures are of my plug installed in my truck to verify fitment.

Thanks guys!

#2

Well foam and hot glue arnen’t going to be happy in a 200 degree plus cure…

THe setup you have done so far is for a room temp layup. So you might wanna continue it as such but use, epoxy that can be used in a higher temp cure. Or just forgo the pre preg and so some wet layup/infusion?

Or you can start over and make a plug for high temp and prepreg. Molds are gonna be more expensive. But with prepreg you’ll have to have an oven. And 200F cure cycle is 4 hours long plus a 356F post cure according to that data sheet.

definitely think this through before you commit

#3

I actually love making air tubes. If you stay using pre-preg for your tooling is the same cost as a high temp wet lay mould then I would look at the plug being able to take the temperature of the pre-preg. But if it will then go for it. Never used Hexcel pre-preg but I have used a number of other makes and have found only two (I have tried about 10 to 12 different materials) that work well OOA. Not sure about the material Mehmet has as I have not used it. Both work well at a cure temp of 70 degrees C (158 degrees F) and although take longer to cure at this lower temp it gives much better results. I have cured it at higher temperatures and it gives me pinholes so I slower cure allows the air ore time to escape.

I would guess the lay up time for this tube was about 2 hours from start to finish with about an hour debulking the first layer.

I only do pre-preg work now. It is quicker for me with less consumables and my oven was so cheap to make that it had paid for itself within the first 4 or 5 parts I made in there…

Here is an idea of the actual size as I make some larger parts in there too…

The only thing with the oven is getting a ramp and dwell controller and wiring it up so the fan runs continuously and the heater only is controlled by the controller. I never go above 75 degrees C so I found the fan motor has been fine even being inside the oven. I have now swapped the fan for a slightly higher flow one as the one in this photo simply wore out as it has been used for about 2 years almost continuously.

#4

hey welcome to the forum! Mind me asking what the cost is for the prepreg you got?

Although the data sheet says that it should be ok with vacbag/oven cure there is no cure schedule provided for said method, just autoclave. So that could lead to a lot of errors in trying to figure out how best to go about it…