Composites Central


Reply
Old 10-21-2014, 01:24 PM   #1
Jonty

Member
 
Join Date: Oct 2014
Location: Cambridgeshire, UK
Posts: 69
Thanks: 5
Thanked 4 Times in 4 Posts



Default Wet Lay Laminating Advice

Hi chaps, I've just got over my first stumbling block where I was trashing moulds from poor release... Thanks to Hanaldo and Elitec for that! So now I'm on to the proper job of actually starting to make some parts... if you can offer advice on how to improve my laminating from the below photos and layup description that'd be really appreciated!

PRF epoxy compatible gel coat
3 plys 200g twill carbon
PRF epoxy
Peelply
Bread wrap
Breather
Vac bagged 28.5in after drop test to find big leak

Damage to mould from poor release after buffing off semiperm like a wax:


Gel coat not wetting out as release agent working very well:


Gel coat released slightly before laminating:


Overview of moulded part:


Detail of air between carbon weave and bridging on external radii (ignore blotches in the middle from gelcoat needing to be brushed out again whilst tacky):


So my requests are for advice on how to achieve a better visual part using wet lay -

What can I do to get rid of the air between the weave?
- I brushed a layer of resin onto the tacked off gel coat, and wetted the Carbon between release film using a filler spreader before putting it in the mould. But despite this the carbon looks quite dry on the inner surface. Breather is quite wet, 2:1 resin to carbon ratio so plenty of the stuff slopping about, 3rd layer went in dry to wetted second layer.

What can I do to stop the bridging?
- I was quite careful putting the carbon into the mould, and after bagging I also went around with a plastic tool to push it into the mould. There is one tiny spot (less than 1cm2) that shows the peel ply bridged, otherwise it is carbon away from the gelcoat, like the top of the last photo. Should I conciously push excess carbon into the recesses of mould? Or should my peel ply be put in several strips to not pull the carbon away from the mould face?

What suggestions do you have to improve my layup process in general?
- am I using the right kit? Should I use a non perforated or less perforated release film like this rather than bread wrap?

Thanks very much for any suggestions!
Jonty is offline   Reply With Quote
Old 10-21-2014, 06:39 PM   #2
Cartoon

Member
 
Join Date: Apr 2014
Location: Australia
Posts: 48
Thanks: 1
Thanked 3 Times in 3 Posts



Default

im roughly at the same stage of making parts as you and have came across some of the same problems so very keen to see the answers.

On my last part i was able to get less bridging by putting the part under vac but stopping before it was 100% under pressure. I would then push in all the corners and then continue to remove the air. still had some issues but a lot less.
Cartoon is offline   Reply With Quote
Old 10-21-2014, 07:25 PM   #3
Elitec

Member
 
Join Date: Aug 2014
Location: Australia
Posts: 26
Thanks: 2
Thanked 2 Times in 2 Posts



Default

Hi Jonty,

I bet on the positive side it's nice to have a new set of problems instead of the same old thing!

Im an just curious - when you pulled vacuum, did you simply pull full vacuum right away or did you gently place the bag into position as vacuum was pulled down gradually?

Phill
www.elitecomposites.com.au
Elitec is offline   Reply With Quote
Old 10-21-2014, 09:27 PM   #4
Oneturboneed

New Member
 
Join Date: May 2014
Location: California, USA
Posts: 4
Thanks: 1
Thanked 0 Times in 0 Posts



Default

I think there might have been to much gel coat before the cloth went on so that the vacuum could not pull the cloth down. Just an idea.
-Shawn
Oneturboneed is offline   Reply With Quote
Old 10-22-2014, 12:34 AM   #5
Jonty

Member
 
Join Date: Oct 2014
Location: Cambridgeshire, UK
Posts: 69
Thanks: 5
Thanked 4 Times in 4 Posts



Default

Quote:
Originally Posted by Elitec View Post
Hi Jonty,

I bet on the positive side it's nice to have a new set of problems instead of the same old thing!

Im an just curious - when you pulled vacuum, did you simply pull full vacuum right away or did you gently place the bag into position as vacuum was pulled down gradually?

Phill
www.elitecomposites.com.au
Hi Phil, yes it sure is nice to be working on a new issue - if every part I make I fix just 1 single issue and get closer to a perfect part I'll be a happy man!

Initially we pulled a full vacuum to check for leaks, then once we isolated that we pulled it down pretty quickly - in hindsight that's pretty obvious to be a cause of some of the bridging - to be fair, we were just hoping to get the thing to release without tearing the mould to bits!

Anyway, would you normally put most of your time into consolidating the part once a partial vacuum is pulled, rather than (still being careful of course) when the laminate is first layed up? And would the way consolidation is done, either when initially being laminated or once the vacuum is pulled, be a factor in the air between the weave? I am a bit unsure of why the breather is so wet yet the bottom of the laminate so dry, hence me question about bleeder materials.

Quote:
Originally Posted by Oneturboneed View Post
I think there might have been to much gel coat before the cloth went on so that the vacuum could not pull the cloth down. Just an idea.
-Shawn
Hi Shawn, you're right there was a lot of gel coat - I couldn't stay at my workshop to brush out once it started to tack off, so ended up making 2 additional stabs at it! But since the gelcoat was essentially cured when I laminated this basically makes the new mould face, so I don't think this would have any bearing on whether the carbon was pulled into contact or not. Thanks for the input though!
Jonty is offline   Reply With Quote
Old 10-22-2014, 12:43 AM   #6
jimff1

Member
 
Join Date: Apr 2013
Location: athens, Greece
Posts: 67
Thanks: 12
Thanked 6 Times in 6 Posts



Default

air between weave: use different type of weave in the backing layers, my choice is biaxial.
bridging: pull vacuum gradually as suggested and for complex shape parts use multiple smaller pieces of peelply, breather etc. to cover the surface for example separate pieces for the "humps" and for the perimeter overlapping themselves rather than one uniform piece for the entire part. that way you will eliminate the chances to have any bridging due to the tension in these layers.
these tricks worked for me.
__________________
http://www.compositeparts.gr
jimff1 is offline   Reply With Quote
Old 10-22-2014, 02:27 AM   #7
Jonty

Member
 
Join Date: Oct 2014
Location: Cambridgeshire, UK
Posts: 69
Thanks: 5
Thanked 4 Times in 4 Posts



Default

Hi Jim, thanks for the suggestions! Biaxial carbon as a backing layer I guess helps prevent the resin being pulled out through the laminate stack I guess? I'll give that a try if there are no other options, but I'm currently running on fumes finiancially at the moment, so if I didn't need to invest in additional reinforcement that would be a help - are there other things I can do to achieve the same effect of reducing resin flow to the breather?

Thanks!
Jonty is offline   Reply With Quote
Old 10-22-2014, 03:27 AM   #8
jimff1

Member
 
Join Date: Apr 2013
Location: athens, Greece
Posts: 67
Thanks: 12
Thanked 6 Times in 6 Posts



Default

Quote:
Originally Posted by Jonty View Post
Hi Jim, thanks for the suggestions! Biaxial carbon as a backing layer I guess helps prevent the resin being pulled out through the laminate stack I guess? I'll give that a try if there are no other options, but I'm currently running on fumes finiancially at the moment, so if I didn't need to invest in additional reinforcement that would be a help - are there other things I can do to achieve the same effect of reducing resin flow to the breather?

Thanks!
i'm guessing you can use perforated film with less holes and try to lay up the layers in 45 degrees, that should reduce that effects significantly.
__________________
http://www.compositeparts.gr
jimff1 is offline   Reply With Quote
Old 10-22-2014, 04:24 AM   #9
Jonty

Member
 
Join Date: Oct 2014
Location: Cambridgeshire, UK
Posts: 69
Thanks: 5
Thanked 4 Times in 4 Posts



Default

Ah yeah good idea, I'll see if I can lay up at 45deg for my middle ply.

Bearing in mind I'm doing cosmetic parts at the moment and perfect surface condition is much more desirable than saving every last bit of weight, is it ill-advised to use an unperforated release film? In a way I'd prefer to go to an extreme and then move back to a workable middle ground, rather than tickling my way towards the optimum from this poor surface condition!
Jonty is offline   Reply With Quote
Old 10-24-2014, 03:28 AM   #10
Jonty

Member
 
Join Date: Oct 2014
Location: Cambridgeshire, UK
Posts: 69
Thanks: 5
Thanked 4 Times in 4 Posts



Default

Latest progress is I gelcoated last night; basically kept brushing out every 10-15mins using only 20g of gelcoat over both parts initially, and then about 45mins later added about another 10-15g. I need to find the right time where the gelcoat is viscous enough to wet out fully without waxing away into puddles like my photo in the first post. Is it just a case of finding the right time to brush out again, or can I use an additive?

This afternoon I'll laminate with the following changes:

3 plys of 200g at 0, 45, 0deg instead of all 0deg
Peelply applied in strips to high/low areas to prevent bridging
double layer of breadwrap to reduce resin flow
more careful consolidation under partial vacuum

Hopefully we'll get a part that looks a bit more pro this time...
Jonty is offline   Reply With Quote
Reply

Bookmarks

Tags
advice, laminating, lay, wet

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -8. The time now is 12:35 PM.
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

Inactive Reminders By Icora Web Design