PCBN (polycrystalline cubic boron nitride)

PCBN (polycrystalline cubic boron nitride)

PCBN is extremely hard and thermally stable, and provides extreme resistance to deformation and wear at high temperatures.

Element Six provides a range of PCBN (polycrystalline cubic boron nitride) products for a range of specialist machining applications.

Polycrystalline cubic boron nitride (PCBN) composites are produced by sintering micron CBN (cubic boron nitride) powders with various ceramics, so as to produce extremely hard and thermally stable tooling materials. Most PCBN materials are integrally bonded to a cemented carbide substrate. CBN is the second hardest material known after synthetic diamond, but has high thermal and chemical resistance properties. PCBN composites provide extreme resistance to deformation and wear at high temperatures – typically an order of magnitude better than the nearest ceramic materials.

About two thirds of all PCBN tools are used for the machining of hardened steels, offering a viable, more cost effective alternative to conventional grinding processes. Other applications are in the machining of hard, grey and high-strength cast iron, and cold and hot-work tool steels. The machining of nickel and cobalt-based superalloys is a significant and rapidly growing application area for PCBN.

The Element Six portfolio of PCBN products range from material with low to high CBN content. The chemical composition and microstructure of Element Six PCBN grades differ greatly depending on the application. Lower CBN content materials (DCC500 and DCN450) tend to be more resistant to chemical wear mechanisms prevalent when continuously turning hardened steels. Where there are interrupts in the workpiece – oil-holes in a shaft, for example – a medium content grade like DCX650 is preferred, as it offers the best combination of wear resistance and toughness.

For applications where abrasion resistance is dominant, as in the machining of grey and hard cast irons, the Element Six high CBN grade, AMB90 is the preferred choice. AMB90 also exhibits excellent thermal properties, and being available as solid (unbacked) materials, provides additional economic benefits. AMB90 is the workhorse grade for the roughing and finishing of brake discs and cast iron engine blocks, and typically outlasts ceramic tools by more than an order of magnitude, whilst operating at cutting speeds in excess of 2500 m/min. For extreme interrupted cutting applications such as the milling of hardened steels, DBW85 and DBS900 are preferred because of their extreme strength and thermal shock resistance. These materials also have a fine grain size, thereby ensuring a good workpiece surface finish and they are used extensively in the fine finishing of cast irons and valve seats.