Pinhole uneven surface

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Pinhole uneven surface

Author	Message
primoz1111	primoz1111 posted 10 Years Ago HOT Topic Details
Group: Forum Members Posts: 3, Visits: 31	Hello! First hi to everyone using this forum, you got nice community here. Ok the PROBLEM I am using 245 2x2 twill 43% resin rich prepreg. As you can see the resin in not equally spread through surface. My product demands 2 layers of prepreg so when i stack the layers i turn the the sides with more resin facing each other then i combine them so the most resin is in the middle of fibres letting the vacuum do its job. When i vacuume the prepreg i use release film perforated and breather all stuck in vacuumbag. My tactic is 3h of vacuuming on room temp then 1-2h on 45C, 1h on 60C and 1h on 70C after that i cure it at 120C for another hour more This is my BEST result : So here is the problem why is here areas of pinhole free surface and with pinholes is it the resin not evenly spread the or the problem is my tactic of vacuuming any tips or help will be nice. P.S. I am using http://shop1.r-g.de/item/390102S vacuum pump Tags pinhole pinhole free prepreg Edited 10 Years Ago by primoz1111
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amgrace	amgrace posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 1, Visits: 18	I'm getting the same surface finish when I vac bag my wet layup. The effect (on both our items) looks like the resin is being drawn away from the surface. I am having issues getting my bag to seal properly which means I have to keep the vac pump running until the part cures - I use a "hot box" to help things along. I was wondering if leaving the pump running and pulling vac ( I get around 28 - 30 inches depending on sealing issue) for that long is causing the issue. Are you able to seal your bags and keep vac with pump off till part cured or do you have the pump running all the time?
	Reply Like 8
primoz1111	primoz1111 posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 3, Visits: 31	I have no problem with sealing. My vacuum stays if i stop the pump but i use pump all the time during the cure process.
	Reply Like 8
Julien	Julien posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 16, Visits: 2.8K	Hi guys, Can you give the technical data sheet of your prepreg ? 2 reasons that may resolve your problem : - The first one, when you cure your preg , (if its a 120ºC class) you have to reach 80°C at 3-4°C/min. Rest at 80ºC during a maximum of 30 min and then up to 120°C for 1h minimum at 3-4°C/min. A 120ºc class prepreg reaches his minimal viscosity at approx 110°C. If you wait too many time under 80°C, the prepreg can cure when the resin is not enough fluid... -2nd thing is that your prepreg is not an "out of autoclave" so it must receive more than 1 bar of pressure. This is why we have to read the TDS. Julien
	Reply Like 9
morepower	morepower posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 242, Visits: 1.2K	You need to get a proper Out of Autoclave pre-preg to be honest. This part is only 2 layers thick and has no pinholes. I made them and sent them out of the mould straight to the customer.
	Reply Like 9
Matthieu Libeert	Matthieu Libeert posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	You say you are using a perforated release film?! must be an unperforated one! ratio fabric/resin is on the limit with prepreg and if you are sucking out more resin with perf releasefilm and breather you'll get pinholes and dry spots Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
	Reply Like 9
Jacopo Carbonio	Jacopo Carbonio posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 43, Visits: 109	I never used pre-preg but looking a lot of video, as Matt said right, they use only unperforeted film and breather to spread the vacuum on the surface but if you use perforated film with this percentage of resin it goes away and you have your result
	Reply Like 8
fgayford	fgayford posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 433, Visits: 1.2K	primoz1111 (17/04/2015) Hello! First hi to everyone using this forum, you got nice community here. Ok the PROBLEM I am using 245 2x2 twill 43% resin rich prepreg. As you can see the resin in not equally spread through surface. My product demands 2 layers of prepreg so when i stack the layers i turn the the sides with more resin facing each other then i combine them so the most resin is in the middle of fibres letting the vacuum do its job. When i vacuume the prepreg i use release film perforated and breather all stuck in vacuumbag. My tactic is 3h of vacuuming on room temp then 1-2h on 45C, 1h on 60C and 1h on 70C after that i cure it at 120C for another hour more This is my BEST result : So here is the problem why is here areas of pinhole free surface and with pinholes is it the resin not evenly spread the or the problem is my tactic of vacuuming any tips or help will be nice. P.S. I am using http://shop1.r-g.de/item/390102S vacuum pump First, Do not use perforated film, use non-perforated film. You are bleeding away the resin rather than letting it flow. Also I would not ramp that slow. Just go straight to your cure temperature, so as to allow the resin to reach its lowest viscosity and flow, before it starts to crosslink. (cure). Hope this helps. Fred
	Reply Like 8
primoz1111	primoz1111 posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 3, Visits: 31	Hello! Tnx for all replays. It was help full ALLOT!!! i did it no pinholes at all i cant be more happy. Tnx for all yours hellp!!
	Reply Like 9
creator	creator posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 9, Visits: 92	primoz1111 (22/04/2015) Hello! Tnx for all replays. It was help full ALLOT!!! i did it no pinholes at all i cant be more happy. Tnx for all yours hellp!! Tags So what you did different my friend ?
	Reply Like 8