Waterjet cutting is a cold-cutting process, which competes with the welding methods of material separation, because of the good quality of cutting surfacesand the absence of thermal deformation and temperature of the edges of objects during the process does not exceed 100°C. The technology used is restored to 4 000 bar pressure stream of water passed through a nozzle with a very small diameter, forming a coherent stream of fluid with a speed of more than three times the speed of sound.
By using this method it is possible to cutting and punching of almost all types of materials except diamond. A stream of pure water with a diameter even less than 0,1 mm is able to cut at high speed paper, leather, rubber, plastics or textiles. In the case of metal objects, the speed is much lower and there is a need for the water fine abrasive powder, such as silica, but the diameter of the nozzle must be more than 0,25 mm. When water pressure of 4 000 bar and a nozzle diameter of 1,0 mm is possible to cut steel sheets with a thickness of 100 mm at speed of abort 50-80 mm/min. To cut very hard materials it is recommended to use abrasive powder of boron carbide.
Waterjet cutting is done only in an automated or robotized manner, using similar control systems like plasma and laser cutting. During the process the head together with the nozzle are perpendicular to the delimited area of the material, but it is also possible gouging and beveling objects, and then is required to tilt the head at a right angle.
This method of cutting taking place on numerically controlled machines, „Waterjet” has many advantages: there are no changes in the structure of the product treated, do not emit gases or dust, obtained a very high quality cut edges. Separation is carried out of materials that are difficult to cut in other ways, such as ceramics, plastics, composites. Allows cutting in explosive dangerous conditions, such as cutting explosive bullets. Using waterjet technology the shock or fire are minimized. But the problem here is the high level of noise, doming up to 120 dB, low speed of cutting and high power consumption by the pomp.