Composites Central

Go Back   Composites Central > General Composites Discussions > Composites Talk

Reply
Old 12-22-2015, 08:38 AM   #1
berridos

Composites Expert
 
Join Date: Feb 2011
Location: madrid
Posts: 202
Thanks: 2
Thanked 3 Times in 3 Posts



Default Alternatives to Polyester for Molds

Hi guys

I need to build a 10m2 mold. If I build this mold with Optimold II I get according to the user manual a weight of 18 kg per square meter after laminating 7 layers of 450g/m mats. That makes for a total of 180 kg for a single polyester mold. I am worried about the handling of such mold. It will require 4 people when ever i need to manipulate the mold. I am even worried if it will break at the middle if lifted from the ends.
Are there any alternatives to poliester? Can anybody recommend a cheap epoxy system suitable for molds (no shrinkage....)? How many layers would I need to laminate if I use epoxy instead and how much weight could I save?
berridos is offline   Reply With Quote
Old 12-22-2015, 09:23 AM   #2
Compositeman

Member
 
Join Date: Feb 2015
Location: Washington
Posts: 101
Thanks: 5
Thanked 14 Times in 12 Posts



Default

Polyester is most definitely the least expensive option, but a mold of that size will be heavy. Epoxy and mat will be nearly the same weight, but will be stronger and will have less shrinkage. Using epoxy, you will be able to get away using fewer layers of mat lamination, which will reduce weight. Another option is to laminate fewer layers, and back the mold with some heavier pour foam, 8lb or more. This will greatly increase the strength of the mold and reduce flex, and will most likely yield a lighter weight mold that can be manageable.

Foam has a tenancy to shrink as well, so you want to complete the entire laminating process followed by the foam backing before you de-mold the plug, very important.
Compositeman is offline   Reply With Quote
Old 12-22-2015, 09:54 AM   #3
Michiel

Composites Expert
 
Join Date: Jul 2012
Location: Netherlands
Posts: 460
Thanks: 8
Thanked 49 Times in 37 Posts



Default

You can skip 1 or 2 layers of 450g/m. I make my mold with 1 layer 450 with a vinylester and then 4 or 5 layers optimold or a similair resin system. Epoxy isn't going to give you big amounts of extra stiffness. A mold off this size is going to be heavy. For strenght you can add some metal or aluminium profiles at the back, but this is not the best solution when you're going to cure them in a oven. You can also add a sandwich or a honeycomb to make if stiffer and stronger.
Michiel is offline   Reply With Quote
Old 12-22-2015, 12:51 PM   #4
berridos

Composites Expert
 
Join Date: Feb 2011
Location: madrid
Posts: 202
Thanks: 2
Thanked 3 Times in 3 Posts



Default

Thanks for the replies.
The user manual states that you need 1,75kg of optimold resin for every square meter of 450 g/m2 mat. That sounds too much to me. How much resin do you consum per m2 in your molds?
berridos is offline   Reply With Quote
Old 12-22-2015, 03:31 PM   #5
Hanaldo

Composites Expert
 
Join Date: Feb 2014
Location: Australia, WA
Posts: 773
Thanks: 1
Thanked 173 Times in 152 Posts



Default

Nope, 1.75kg sounds spot on. Tooling resins like optimould need to be layed up at a resin:fibre ratio of 4:1.

I'm not sure, but I believe this will be because of the expanding additive in the resin. It makes the resin heavier, so you've got less resin per kg. The fibreglass still needs the same amount of resin, so you need to use more to wet out the fabric.

Last edited by Hanaldo; 12-22-2015 at 03:43 PM.
Hanaldo is offline   Reply With Quote
Old 12-22-2015, 03:42 PM   #6
steyrn

Member
 
Join Date: Nov 2013
Location: Spain
Posts: 16
Thanks: 5
Thanked 2 Times in 2 Posts



Default

I build my big toolings with Lantor Coremat XM 10mm, resin uptake is 6.5 Kgr./m2
steyrn is offline   Reply With Quote
Old 12-23-2015, 08:15 AM   #7
berridos

Composites Expert
 
Join Date: Feb 2011
Location: madrid
Posts: 202
Thanks: 2
Thanked 3 Times in 3 Posts



Default

Do you combine the Lantor Coremat with poliester resin or epoxy?
berridos is offline   Reply With Quote
Old 12-23-2015, 10:13 AM   #8
steyrn

Member
 
Join Date: Nov 2013
Location: Spain
Posts: 16
Thanks: 5
Thanked 2 Times in 2 Posts



Default

I utilize polyester resin, not Optimold but something similar, Nord Composites tooling resin that I combine with CSM 450 gr/m2 and Lantor Coremat XM 10mm to build my big toolings. Resin uptake is 1.1 Kgr. of resin for square meter of CSM 450gr/m2.
steyrn is offline   Reply With Quote
Old 12-23-2015, 10:59 AM   #9
berridos

Composites Expert
 
Join Date: Feb 2011
Location: madrid
Posts: 202
Thanks: 2
Thanked 3 Times in 3 Posts



Default

Very interesting. Nord Composites was my other alternative. Would you be so kind to describe how many layers of 450 mat you wet out below and above the coremat?
Do you laminate in one shot or like in Optimold where you laminate 4 layers and afterwards 3 additional layers?
berridos is offline   Reply With Quote
Old 12-23-2015, 12:56 PM   #10
steyrn

Member
 
Join Date: Nov 2013
Location: Spain
Posts: 16
Thanks: 5
Thanked 2 Times in 2 Posts



Default

I laminate in two shots. First was three layers of CSM 300gr/m2 with vinylester resin also Nord Composites. Second shot with three layers of CSM 450gr/m2 - Lantor Coremat XM 10mm - two layers of CSM 450 gr/m2, all this with polyester resin.
steyrn is offline   Reply With Quote
Reply

Bookmarks

Tags
alternatives, molds, polyester

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 12:37 AM.
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

Inactive Reminders By Icora Web Design