In this video tutorial we work from a 3D printed mould, coat with release agent and directly hand laminate a carbon fibre part, after curing the part is released trimmed and coated with epoxy coating resin to create a perfect cosmetic finish.
This tutorial can be followed to make moulds suitable for and ambient cure process including wet-lay-up, vacuum bagging and resin infusion.
How to use a 3d printer to directly print a mould suitable for ambient temperature processing
How to perform a simple hand layup in carbon fibre
How to coat the finished part to provide a perfect cosmetic finish
Typical composite processes involve the production of a pattern from which to create a mould but for development and prototype parts it is possible to skip the pattern making stage and directly create a mould using 3D printing technology. This particular project has been kept as simple as possible in order to allow parts to be made with the bare minimum investment in equipment, please look through some of our other projects if you are looking for information on more advanced commercial techniques.
We will be taking an FDM print with the barriers already modelled and release coating this before manufacturing the carbon fibre part using a simple hand layup process.
For non-cosmetic parts they could be used directly from the mould however the surface will be slightly compromised by the resolution of the print and limitations of a hand layup process. To bring the finish up to a perfect standard the part can be coated in XCR coating resin and flatted and polished to a high-quality finish.
There are a wide range of print materials that can be used for mould making however we strongly recommend using PETG, this offers good inherent release properties with epoxy resin and is readily available and easy to print. In particular ABS should be avoided as a direct mould material as, although not impossible, getting a good release from epoxy resin can be problematic.
After printing the mould should be prepared with release agent, the most reliable release agent to use in this process is PVA release agent, this offers good layer-line levelling and reliable releasing from epoxy resin.
A mould printed in PETG and release coated with PVA will be compatible with most conventional resin systems such as epoxy polyester and vinylester, generally moulds made in this way are best suited to hand layup processing (with or without a vacuum bag) it would also be possible to process using resin infusion but due to 3D prints generally not being 100% airtight an envelope bagging method may have to be employed. Moulds made with this process are not suitable for elevated temperature cures as used in prepreg production, even when the HDT of the PETG is not theoretically exceeded, in practice we have found the stress of the vacuum bag will lead to excessive warping and distortion.
Materials and Equipment Needed
To Create the 3D Printed Mould
You will need a properly configured and setup FDM printer, in this project we have used the excellent Ultimaker S5 which with its pre-sets and intuitive user interface makes 3d printing easy, however any printer that is properly configured can, obviously, be used. If you are looking for advice on 3d printing we would be happy to recommend our suppliers Dynamism.
We recommend using PETG filament, we have found this to offer an excellent balance of inherent release properties and accuracy, other print materials may well be appropriate, but test should be conducted to ensure compatibility with the process.
To Release Coat the 3D Printed Mould
PVA release agent offers a fast and effective release surface onto a 3D printed mould and whilst release waxes can also be used in this application, they generally will not offer quite the same ease of release. Chemical release agents are not usually the best option in this process as they only provide a thin film and do not serve to level out the printing layers.
To Laminate the Carbon Fibre Part
In this project we are using 3 plies of our most popular fibre which is our 210g 2/2 twill carbon but equally any dry composite reinforcement can be used depending upon your application. The resin used is the EL2 laminating epoxy which is specifically designed for wet layup processing and offers excellent strength and wet-out performance. The back of the part is then finished with our economy peel-ply which provides a neat inner surface.
To Coat and Finish the Carbon Fibre Part
For both repairs and coating we use the XCR coating resin which is specifically designed for coating and finishing applications like this. If void repair is required Flash release tape is useful for creating dams and a range of wet and dry paper, as found in our Mirka combination pack will be needed if you intend to flat and polish the part. If the finish has been flatted the NW1 polishing compound can be used to bring the component through to a full gloss.