Just a quickie: Imagine I have a flat tool, eg a tempered glass sheet or thick steel and want to make a sandwich panel or solid laminate with two moulded surfaces. If a caul plate was put on top of the laminate (again, eg glass or steel) to provide the other moulded surface, would the placing of the caul plate significantly impact the removal of air and volatiles when placed in a vacuum bag? Im assuming it would, but how great is the effect?
thanks
yes it would. Infusing, or using the correct type of prepreg would solve that problem
Personally I would use an aluminum caul plate minimum of .032" This is a diagram from one of my manuals which is how I bag things, the caul plate would normally be between the heating blanket and the non-perforated release film. It’s always worked for me with prepreg and doing wet layups.
Flybynight:
Does that yeild a slicker finish on the bag side of the part than doing it without the caul plate?
Zach
Yes without the caul plate the resin just gets eaten up by the bleeder/ breather and leaves a very rough canvas like finish. The caul plate allows the resin to pool and force itself to the edges of the part. But keep in mind your release film plays the biggest part in your finish. The smoother the material, the smoother the finish. But if you are going to do any secondary bonding or paint, a rougher finish is the most desireable for adhesion.
cool thanks. I could imagine that would be the case, but say you had the caul plate right next to the laminate without breather below it…hmmm
Yeah I always put the caul plate under the breather. Now my caul plates are covered in Teflon ;), pricey but very worth it. You can even use the bagging material and tape it around the caul plate if you want a nice non-stick finish.
You should be carefull with things such as teflon or ptfe being in direct contact with your composite parts as it can effect the laminate and cause bond failures. There are ways around it but caution should be applied and they should’nt be used if the part is to be structural.
Matvd. I think the main concern there is using teflon rubbing tools for prepreg. The teflon can chip/scrap/etc off between the layers. Using a teflon coated caul plate would cause no problem, unless pieces rip off (if film)and you need to bond to the surface later. Release sprays are a concern if you spray your tool near your fabric. It can coat the fabric and obviously, not bond well. I think Silicone can leech into resin as well, but i think that is also a liquid release issue as well.
FlybyNight. Yeah, I’ve wrapped my cauls in everything from release film (all types) and bagging film that I put Frekot on. Mostly because I wanted to keep my caulplate smooth, without resin buildup.
Yes riff42, you are correct. I use the teflon sheets that look like a wax paper. We cut them to size and use high temp tape to attach them to the caul plate. It’s pretty stout stuff too, it cuts really nice, but won’t tear unless you put some force behind it.