CARBON PREPREG, WHAT IS IT?
Carbon prepreg is the manufacturing process we use the most in our Foil and Co. company. Indeed, carbon prepreg, as its name suggests, is a fiber that is already impregnated with resin. The polymerization and therefore its hardening will only take place when the temperature rises. The part will obtain all mechanical properties after a curing time. Today, this manufacturing process is widely used in the aerospace industry, particularly because of the precision and quality it provides.
The advantages are multiple:
- We achieve maximum strength properties thanks to an evenly distributed resin.
- The variation of the curing process is the same between parts, allowing the part to be repeated several times.
- No more consumables and waste compared to composite infusion.
- A “glassy” surface finish at the exit of the mold and curing process provides a smooth and glossy surface.
Carbon fiber prepregs are more expensive than conventional fibers. In the same way, they must be used under certain conditions in order not to deteriorate the mechanical properties.
CARBON PREPREG, TECHNICAL
CARBON FIBER APPLICATION
We will first cut our carbon prepreg rolls using a digital laser. This will allow us to obtain the different fibers that we will simply have to put in the mold. Beforehand, a mold with the shape of the desired part has been machined. Depending on the number of parts desired (prototyping, pre-series, series), the material of the mold is chosen with a direct impact on the cost of the latter. Thus, we will turn more to medium or MDF for mold machining in order to test concepts at lower cost without neglecting the structural aspect of the parts. On mass production parts, we will work with aluminum molds.
Once the carbon fibres are deposited in the mould, it is put under a heating press for a cooking time that can vary from 6 to 12 hours. The compression will plate the fibers and allows to obtain a perfectly smooth surface when demolding. The rise in temperature will allow the polymerization of the carbon prepreg. A temperature sensor is inserted in the mold to ensure perfect precision and obtain a part with optimal mechanical strength and rigidity.
After baking, the mould is cooled and the piece can be extracted. A routing is made with a digital milling machine. We use a numerically controlled machining center with a vacuum table to hold the part during the machining process. The last step consists of sanding and finishing. This is a very fast operation given the already very clean surface state at the exit of the mold.