Definition of ultra hard cutting materials
The term ultra hard cutting materials describes all cutting materials that are classified above carbides, cermets and cutting ceramics on the hardness scale.
Within this definition, it is possible to differentiate between two groups:
- Diamond cutting materials
- PCBN substrates
Diamond cutting materials can be split into two main groups, monocrystalline and polycrystalline, whereby polycrystalline is then split into a further two subgroups.
Monocrystalline diamonds are used in finishing and superfinishing processes. Optimum surfaces and maximum geometric accuracies for the components are the focus here. High chip volume is secondary to these criteria.
Polycrystalline diamond cutting materials, PCD and CVD-D differ primarily in terms of how they are manufactured and their structure.
PCD describes a cutting material group in which the diamonds are sintered as grains in a metal matrix. Each individual grain is itself monocrystalline. Different properties are produced due to the variation of the grains.
CVD-D (chemical vapour deposition) is deposited from the gas phase. The suffix "D" stands for thick film and is used to differentiate it from conventional diamond coating. Thick film describes the thickness (0.3 - 1 mm) of the cutting material that is soldered to the carbide toolholder for further processing.
PCBN (polycrystalline cubic boron nitride) substrates have different properties due to their composition.
These are configured specifically for the application.