This is the second part of our most recent video series. In this video we demonstrate how to using carbon fibre tooling prepreg to create a prepreg carbon fibre mould. The benefits to making prepreg moulds is that they have a relatively high service temperature (135°C in this case) which is difficult (although not impossible) to achieve with a hand layup process. 

Because the XT135 out of autoclave tooling prepreg uses carbon fibre reinforcement it has an extremely low CTE, lower than can be achieved using metal or glass fibre, this can be quite important when making prepreg carbon fibre components that need to be produced to high accuracy; the reason being carbon's incredibly low CTE - if you use materials with a higher CTE to produce the tools then you 'bake in' the expanded dimensions of the higher CTE mould when you cure carbon prepregs in them at elevated temperatures.

Tooling prepregs also have the advantage of being actually pretty quick and very reliable to work with. Certainly, providing you understand the process and have the right materials there is probably less 'skill' involved in making a good quality prepreg mould compared to hand-layup with more conventional materials (such as Uni-Mould).

Here's the video tutorial demonstrating the layup process for a tooling prepreg (which is quite a bit different to laying up a prepreg component):


If anyone has any questions at all about tooling prepregs or any of the topics raised in this tutorial please post them below, I'd be happy to answer.

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Is it recommended when working with XPREG prepregs to make the surface ply a few millimetres larger than the backing ply? It was a recommendation in your “Beginners’ Guide To Out Of Autoclave Carbon Fibre”. However the recommendations of this guide are based on Easy Composites old line of carbon fibre prepregs: Easy-Preg.

Here is the relevant passage out of the above mentioned guide:
“In most cases, when laminating a part the surface ply should be made a few millimetres larger than the backing ply/plies. This is done to ensure that the air path that is created by the special dry side of the Easy-Preg Surfacing Prepreg is not maintained all the way out of the laminate ensuring that any air trapped in the reinforcement can be removed when the part is vacuum bagged. In practice, it is not necessary for the surfacing ply to extend beyond the backing ply all the way around the part but it should be aimed for as a matter of good practice. Although you could make templates, one for the surface layer and one for the backing layer, it is usually sufficient to simply mark out the surface layer by drawing slightly wider than the template when you transfer the template to the prepreg material, making a separate template for the surface layer unnecessary.”

Matt Statham
Easy Composites / Carbon Mods - Technical Sales