Concurrent cutting method to Laser cutting one is Water Jet stream cutting method. Generally it characterizes with good after cut surface quality and, what’s most important, a lack of deformations and temperature influence on being processed material. Water Jet cutting technology is called ‘cold cutting’ and allows to process a variety of material kinds excluding diamond only.
Cutting materials with water as a cutting factor is a process with highly compressed water stream usage which is sent through a nozzle with a very small diameter. As a result we can receive a high speeded (three times faster than the speed of sound) thin water stream. The water coming out of the nozzle extracts out the material residue form the crack as a result of erosion and being cut material fatigue. High local stresses are accompanying this process. Depending on hardness and other physical/chemical parameters of processed material the water stream is mixed with worn powders like garnet, olivine, silicon. Their main purpose is to make cutting process easer and to apply surface micro processing which finally affects the quality, obtaining necessary dimensions to its planned originals. Water Jet cutting method is analogical to Laser one if the automatic or robotic integrated steering mechanisms are concerned.
Cutting head with installed cutting nozzle is usually set perpendicular towards processed material. Tilting head with a certain angle is also possible if the diagonal cutting and grooving is necessary. At the moment there are three types of machines which are using water-abrasive cutting technology: - with a water pressure up to 70Mpa and nozzle diameter up to 3mm, mixing water and abrasive takes place in mixing chamber connected to a cutting nozzle, - with a water pressure up to 70Mpa and a direct water-abrasive mixture inside 3mm cutting nozzle injection, - with a water pressure between 200Mpa and 400Mpa where mixing water and abrasive takes place in chamber connected to a 1mm cutting nozzle.
The basic technical parameters in Water Jet cutting technology are as follows: - cutting speed measured in [m/min], - water pressure measured in [Mpa], - abrasive supply efficiency measured in [kg/min], - type and mesh of abrasive measured in [mm], - distance between the nozzle and the material measured in [mm], - nozzle geometry. Cutting speed is one of the most important parameter in that type of material processing method. Mostly it depends on hardness and thickness of the material.