Waterjet operation costs consist of:
- wearing parts of the pump
- mixing nozzles and tubes in the head
In Waterjet systems used for water cutting two types of high-pressure pumps are applied: direct (crank) and indirect (pressure amplifier).
Pressure intensifier pumps emerged first. In indirect pumps the oil at a pressure of 200 bar is pressed into the piston pressure amplifier with 1:20 ratio, and thus in the output (water) stage the pressure of 4000 bar is obtained. Additionally, intensifier pumps reach the power of 50HP (crank 30HP), which significantly expands the scope of orifices of various sizes directly affecting the quality and processing efficiency. Intensifier pumps applied in Kimla Waterjet machines provide a smooth and free pressure regulation from 500 bar, which automatically solves the problems occurring in crank pumps.
In crank pumps water is pumped through three piston driven by a crankshaft. The only positive feature of the crank pump is obtaining greater efficiency (about 10%) than in case of classic pumps. This is due to the lack of indirect supply of oil which heats up during operation.
The pressure generated by crank pumps is 3500 bars and in modern intensifier pumps it comes to 6000 bars (during tests the pressure up to 14,000 bars was obtained). Additionally, crank pumps are even four times more expensive to operate, because the frequency of piston movements is several dozen times higher, which leads to frequent replacement of expensive wear parts. Having some savings in electricity the cost of operating a classic pump is still about half the cost of operating a crank pump.
Another serious problem in the use of crank pumps is the lack of ability to stop the pump immediately, which leads to large losses of energy and water.
Moreover, the limited possibility to adjust the pressure by controlling the engine speed with the inverter, which occurs in crank pumps, increases operating costs. The minimum engine speed that provides its reasonable cooling gives too high pressure for safe piercing and cutting glass, which results in the need to use additional heads which limits the energy of water stream.