Nozzles are often composed of sintered boride or a tungsten carbide composite. Most cuts have a taper of less than one degree, which can be lowered or avoided totally by slowing down the cutting process or tilting the jet. Slower speeds and/'tilt'ing angles may not be possible with some harder materials. Harder materials require higher pressures to cut the same depth as softer ones. The most common nozzle material is tungsten carbide because it has good erosion resistance and can withstand the high temperatures of the plasma jet. However, it is also the most expensive material available. Boron carbide is another option because it is less costly but it will wear out faster than tungsten carbide. Silicon carbide is yet another option because it has better hardness and toughness than boron or tungsten carbide but it is also more expensive. Diamond is another option if you can find a supplier that sells it in the form of inserts. It has excellent heat transfer properties and does not get damaged by the heat of the plasma jet. The type of cutter used depends on what type of material you are trying to cut. For example, if your material has holes in it then you should use a hole-cutting nozzle, if it's flat surface-oriented material then you should use a flat-cutting nozzle.