Wind of changes in the machining of composites.

PTFE (polytetrafluoroethylene - Teflon ™), PMC (polyester matrix composites) and CFRP (Carbon Fibre Reinforced Plastics) offer high performance requirements for the marine, aerospace and aviation sectors. However, they can also cause problems such as delamination and poor surface quality during machining, particularly as tool life is very short due to the abrasive characteristics of the materials being machined. All these problems can be avoided, and time and costs reduced, simply by using special laser-ground PCD cutters.

PCD (PolyCrystalline Diamond) was the main actor in special tests conducted recently in an advanced laboratory of a leading F.1 team (whose name is protected by NDA, No Disclosure Agreement). Processing with special PCD gave excellent results. Although it is not possible to report more for the reasons stated above, the final report clearly shows that polycrystalline diamond cutting tools with laser sharpening achieved a 30% cost saving. In fact, laser technology allows the diamond cutting edge to be sharpened and shaped into perfect special shapes to meet customer requirements. This is a prerequisite to avoid the development of heat due to friction between the cutting edge and the processed material. As is well known, heat generation alone is the main cause of deformation, and inappropriate machining can lead to shrinkage, fiber fraying, edge chipping and delamination.

All these difficulties can be avoided by refining the machining parameters for different composite materials:

• very high angles (150-180°)
• very low feed speed (<0,05 mm / min)
• high cutting speeds (300-400 m / min)

The use of PCD is not new, but laser technology on PCD cutting edges shows new scenarios: tailor-made solutions can be developed for the different requirements of composite materials. By simplifying the machining process, better surface quality can be achieved. In addition, cutting edges can be sharpened over and over again.

Isn’t time for a change?

Case Histories:

• composite materials in modelling
• Conical reamers for graphite