CFRP, carbon fibre, carbon fibre reinforced plastic, carbon fibre, carbon fibre, carbon fibre reinforced plastic (hence the abbreviation CFRP) - all these terms refer to the same material: a composite of carbon fibres, which are embedded in a matrix in the form of threads parallel to each other, crosswise as a fabric or as a well-ordered textile fabric. The matrix is a castable, duroplastic plastic, mostly epoxy resin or polyester.
Carbon-fiber-reinforced plastics have special physical properties, especially exceptional strength and stiffness - it is indeed surprising to hold a three-millimeter-thick rod in your hands and not bend it as you would expect. The material is particularly light, has very good vibration damping and low material fatigue, even under permanent dynamic load. It can be said that CFRP is significantly lighter than aluminium, but at least as strong as steel in terms of strength. Further advantages are low thermal expansion and good corrosion resistance.
During production, the fine carbon fibres are bundled into individual, thicker rovings. These are further processed depending on the field of application: For example, they are cut into small pieces and used for laminating. Single- or multi-directional scrims and fibre mats are also used for this purpose, in which the fibres are arranged either strictly in one direction or crosswise. The most stable form, however, is further processing into textile fabrics in which the structure of the braid can be precisely matched to the way the component will be subjected to the load it will be subjected to. The highest strengths are always achieved in the direction of the fibres - so it is obvious that a fabric structure in which the fibres run in different directions is more stable than a unidirectional fabric.
Semi-finished products made of CFRP are essentially produced in three different processes:
A high fibre content is desirable - this is usually between 50 and 80 percent - 60 percent fibre content can be regarded as a solid standard value.
The future belongs to carbon! This statement may be a bit flat and bold, but the areas of application are still increasing. CFRP is mainly used for rigid constructions:
More generally, the most common application is as a stable tube, profile or rod, which is extremely stable with small diameter and weight.
CFRP parts can be sawn with a hacksaw or a circular saw; the problem is that the fibres fray a little at the ends and post-processing does not significantly improve the interface. A band saw with diamond-studded band saw blade is ideal. Alternatively, a fine boring grinder with (diamond-coated) cutting disc is recommended.
CFRP can be drilled with a conventional carbide drill (at rather low speeds), but diamond-studded tools are better. The drill holes will fray less if you drill into a soft surface (wood, plastic).
The material is best bonded with a two-component epoxy-based adhesive. With pipe or rod extensions, however, an (additional) internal or external mechanical connection in the form of a sleeve or connecting piece is generally better.
CFRP semi-finished products are easy to paint, but it should be noted that they often have a release agent film on the outside. So, as is generally the case, first sand and clean, then varnish.