The challenges of machining lightweight materials, such as CFRP and GRP, are high tool wear and material-specific processing errors. The severe tool wear is due to the highly abrasive properties of the fibers and the transfer of material to the tool surface. This shortens tool life and impairs the quality of product edges.
Most machining tools have a thin coating applied to their surface. This coating can make tools with a resilient body more resistant to wear. For example, several layers of hard material, such as titanium carbide, titanium nitride, titanium carbonitride, aluminium oxide, titanium aluminium nitride, chrome nitride or zirconium carbonitride, can be applied using PVD, CVD or PACVD processes. A number of new coatings have also been developed, e.g. metalliferous molybdenum disulfide layers, CVD diamond layers and amorphous carbon layers DLC (diamond-like carbon).
The advantages offered by tools coated with hard layers over non-coated tools when machining CFRP and GRP include high wear resistance, lower process forces, a longer tool life and higher cutting speeds. The main disadvantages are the risk of layers flaking or chipping, poor resistance to fracturing and the complex layer deposition process involved. Polymer layers adhere better and are relatively cheap and easy to apply. However, compared to hard layers, they are much less resistant to wear.
The use of innovative tool coatings for machining CFRP and GRP efficiently calls for new design concepts for machining processes. Our R&D work therefore focuses on the following: