HOW DOES A WATERJET WORK?
There are two main steps involved in the waterjet cutting process. First, the ultra-high-pressure pump or Electric Servo pump generally pressurises normal tap water pressure levels above 50,000 psi (3450 bar) to produce the energy required for cutting. Second, the water is then focused through a small precious stone orifice to form an intense cutting stream. The stream moves at a velocity of up to 2.5 times the speed of sound, depending on how the water pressure is exerted. The process is applicable to both waters only and abrasive jets.
For abrasive cutting applications, abrasive garnet is fed into the abrasive mixing chamber, which is part of the cutting head body, to produce a coherent and an extremely energetic abrasive jet stream.
About the pump
There are two types of pumps used to create this high pressure; an intensifier pump and a direct drive pump. A direct drive pump works much like a car engine, forcing water through high pressure tubing using plungers attached to a crankshaft. An intensifier pump creates pressure by using hydraulic oil to move a piston forcing the water through a tiny hole.
Of course, direct drive pumps are inherently more efficient than booster pumps because they do not require power-consuming hydraulic systems.The crankshaft drive is a purely mechanical direct drive system with minimal friction loss, so the efficiency is usually between 85% and 90%.This means that 85% or more of the electric energy supplied to the drive motor can actually be delivered to the cutting nozzle compared to 65% or less of a conventional supercharger
Abrasive Waterjet Nozzle
1. High Pressure Water
Water pressure is generated at the pump and travels to the nozzle body through high-pressure tubing. Water pressure is variable at the pump
2. Jewel Orifice
Using a ruby or diamond jewel, the orifice focuses the high-pressure water. The diameter of the orifice helps determine the cut width (kerf). The smaller orifice, the smaller the cut width(kerf).
3. Abrasive Inlet
Introducing abrasive (usually garnet)to create a mixture capable of cutting nearly any material.Abrasive is categorized by mesh, similar to sand paper, with 60 mesh being the coarsest and getting finer from there.
4. Mixing Tube
With the abrasive and water together, the mixture is delivered through the mixing tube cutting the material. Mixing tubes
vary in size depending on water pressure, abrasive mixture, and application. Similar to the Jewel Orifice, the smaller the diameter of the mixing tube, the smaller the cut width (kerf).
All SAME waterjet nozzles are individually tested within our factory to ensure that the configuration and design of the nozzle meet our standards and guidelines. This ensures long-lasting use and efficient cutting.
Cutting Speed depends on the following variables:
Material type – harder materials cut more slowly
Material thickness – thicker material of a given type cut more slowly
Waterjet Pressure – higher pressure cuts faster
Volume of Abrasive – higher abrasive in the stream cuts faster
Cut quality desired – rougher finish is a faster cut
We can provide software to calculate the approximate cutting speed of various materials
Abrasive is generally stored in bulk hoppers of between 250kg to 2Tonne. The abrasive is automatically fed from the bulk hopper to a small metering hopper mounted on the machine. The metering hopper allows the correct amount of garnet to feed to the cutting head. As the waterjet passes through a mixing chamber it creates a venturi effect which draws in the abrasive. The abrasive clings to the water stream and is directed into the Focus Tube (or Nozzle Tube) and is then blasted into the material to begin the erosion process.
Your water quality should be tested and any treatment will be advised.
Testing your water is recommended to see what quality your water is. We can then compare the results to our water chart to see whether you have water quality that is optimum for ultra-pressurization.