2nd infusion, help needed


Author
Message
Eeskidmark
Eeskidmark
Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)
Group: Forum Members
Posts: 6, Visits: 106
Hi all,

I have just done my second ever resin infusion on a small part I have.

The finished part is very strong, with 6 layers of CF, but the surface finish is not what I expected. 

I am starting to believe it is because the mould has sharp 90 degree edges so the fabric cant get right into the edge. But the fabric has also held off on other areas, and the resin looks like it has been spread to thinly. I used some 3m 77 spray glue, but i only used a very fine mist to help it stick to the mould. I also worked the fabric the best I could into the edges whilst i was pulling a vacuum. 

I did have a good vacuum as I clamped the hoses and left it for 20 minutes and the needle never moved when I released the clamps. 

I have attached some pictures, would anyone be able to give me any pointers on how to improve the surface finish, should I be using a clear coat?

I think I can save the part with a bit of sanding and a clear coat of lacquer. The mould possibly needs polishing but I was only going to do that once I have the technique right. 

Thanks

http://www.talkcomposites.com/Uploads/Images/676786f4-7d38-4155-b852-6c39.JPG
http://www.talkcomposites.com/Uploads/Images/8d3cdefe-61e9-43af-a4a6-66ca.jpg
http://www.talkcomposites.com/Uploads/Images/1add5888-dbdd-4fc7-af6e-10e1.jpg
http://www.talkcomposites.com/Uploads/Images/d4199720-ea20-448b-b722-aa4a.jpg


VVS
VVS
Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)Supreme Being (1.9K reputation)
Group: Moderators
Posts: 226, Visits: 334
Ive been there and you are close.

keep the overlap as small as you are comfortable cutting and try using a few strips of peel ply instead of one, the bag always locks onto the flat areas of you part first and so this stops the cf seating,

it won't stop the voids completely but help.

Some of the edge fault would be better if you leave the inlet pipe open longer before clamping it off, let a little more resin in and again it helps.
scottracing
scottracing
Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)Supreme Being (3.9K reputation)
Group: Forum Members
Posts: 460, Visits: 5.2K
you need to ensure that prior to infusing the bag is properly vac'd and there is a bit of excess bag in the corners. I mould make a small tool (spatula) that you can force the material into the corners when pulling a vac.
I would also cut some small strips that go into the 90 degree corner, if you use a sharp scalpel when laying the first ply and place it into the corner with a small strip of material to overlap it this should help a bit. You can do sharp corners but they can be a PITA.
Its much easier to do with prepreg but you would still need to work the material into the corner and then make some UD bootlaces (but thats another story)

But as above leave the inlet pipe open a bit after you have shut the vacuum, the extra resin that gets pulled in will help a lot with the part. I dont think you are far off from a good part, you going to clear coat afterwards?
Hanaldo
Hanaldo
Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)
Group: Forum Members
Posts: 2.5K, Visits: 28K
As above. It's only basic errors that are costing you, so you're not far off. It's a learning curve that everyone goes through. 

The fabric will handle the corners you've got on that piece no issues. Be sure that when you are working it into the corners, you are paying attention that the fabric you have already positioned isn't being pulled out of place again when you are working somewhere else. I suspect that is your main issue if you say you did work the fabric into the mould, the bridging in the middle is likely to be the result of getting it into the mould, then moving on and not holding that spot (which is the deepest  spot on your mould) in place, so it pulls out again. 

Otherwise, I'd say you are also a touch resin starved. That is likely to be caused by the bridging, but I think until you get the hang of it, make your parts resin rich. 
Eeskidmark
Eeskidmark
Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)
Group: Forum Members
Posts: 6, Visits: 106
Ok thanks for the replies, that gives me a bit of confidence. 

Should I be leaving the vac pump on for the full 24 hours or should I clamp both lines and leave it?

I would like to clear coat my part, can I just use some ordinary paint lacquer or does it have to be 2k because I am not really set up to be handing 2k. 

 How will two layeres of peel ply help me? Does it allow the bag to move over the material a little easier?

I will have another go! 
Hanaldo
Hanaldo
Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)Supreme Being (21K reputation)
Group: Forum Members
Posts: 2.5K, Visits: 28K
I think you've misread that, it's not 2 layers of peel ply but rather the one layer cut into smaller strips. Peel ply is quite tough stuff, so if it's bridging then it can run your part. By cutting it into strips you both make it easier to lay into the mould and allow it to move around more. 

To be honest though, I find it a pain in the ass to peel off strip after strip of peel ply. I prefer to make the peel ply much bigger than required, and just tape the edges around the edge of the carbon so that you've got plenty of surplus, much like vac bagging. This will also prevent bridging. 

As for clear coat, for post-mould coating you can use anything you like, single pack is fine. 
Eeskidmark
Eeskidmark
Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)
Group: Forum Members
Posts: 6, Visits: 106
Ok, thank you.

I will have another go bearing these points in mind. 
Eeskidmark
Eeskidmark
Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)Forum Member (40 reputation)
Group: Forum Members
Posts: 6, Visits: 106
Ok, thank you.

I will have another go bearing these points in mind. 
GO

Merge Selected

Merge into selected topic...



Merge into merge target...



Merge into a specific topic ID...




Similar Topics

Reading This Topic

Explore
Messages
Mentions
Search