Ceramic grades can be applied in a broad range of applications and materials; most often in high speed turning operations but also in grooving and milling operations. The specific properties of each ceramic grade enable high productivity, when applied correctly. Knowledge of when and how to use ceramic grades is important for success.
All ceramic cutting tools have excellent heat and wear resistance at high cutting speeds. Below you can find the most common types of ceramics used in hard and/or difficult to machine materials.
Sialon (SiAION) grades combine the strength of a self-reinforced silicon nitride network with enhanced chemical stability. Sialon grades are ideal for machining heat resistant super alloys (HRSA). CC6060, CC6065
Whisker-reinforced ceramics use silicon carbide whiskers (SiCw) to dramatically increase toughness and enable the use of coolant. Whisker-reinforced ceramics are ideal for machining Ni-based alloys. CC670
Silicon nitride ceramics (Si3N4) represent another group of ceramic materials. Their elongated crystals form a self-reinforced material with high toughness. Silicon nitride grades are successful in grey cast iron, but a lack of chemical stability limits their use in other workpiece materials. CC6190, CC6090
Oxide ceramics are aluminum oxide based (Al2O3), with added zirconia (ZrO2) for crack inhibition. This generates a material that is chemically very stable, but which lacks thermal shock resistance. CC620
General limitations of ceramics include their thermal shock resistance and fracture toughness.
The speed should be balanced to create enough heat in the cutting zone to plasticise the chip but not too high to unbalance the ceramic. The feed should be selected to give a chip thickness which is high enough to not work-harden the material but not be too high to cause edge frittering.
Higher feeds and depths of cut require a reduction of the cutting speed. These boundaries will change depending upon the component material hardness and grain size.