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The waterjet trimming technology |
The principle of the water jet cutting consists in propelling water at a very high speed (600 to 900 m/s, i.e. 2 to 3 times the speed of sound). The water is compressed through a very high pressure pump (pressure between 2000 and 4000 bars), conducted towards an accumulator and then propelled through a nozzle Ø 0,10 to 0,4 mm.
 Pure water jet is used on soft materials : plastics, moquette, foam, acoustic materials, rubber…
The jet with particles or abrasive water jet can cut metals (steel, titanium, aluminium,…) as well as very hard materials (marble, glass, kevlar,…) with no heat constraints regarding the cutting. Process advantages
No direct contact with the part.
Access to very complex shapes and areas.
Technology adapted to any type of material. Pressure intensification process The heart of a water jet cutting system is a High Pressure Pump called intensifier.Quite simply, the intensifier is made up of 2 stages : the main part of which being a 2-section alternative plunger, with a surface proportion of about 20 depending on each manufacturer.
Water flows across an intensifier composed of a double effect jack. Each side of the jack receives a pressure of 50 to 200 bars. At the same time, this jack drives a plunger into a high pressure cylinder. | 
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The intensification process can be explained as follows : P1 x S1 = p2 x s2With a section proportion of 20 with an oil pressure of 200 bars, water pressure obtained is 20 x 200 = 4000 bars. Water pressure can thus vary according to oil pressure. P1 : pressure in the medium pressure cylinder. P2 : pressure in the high pressure cylinder. S1 : plunger proportion in the medium pressure room. S2 : plunger surface in the high pressure room. Waterjet characteristics As an example, the exit speed of a 3000-bar waterjet is about 500 m/s.
The jet is divided in 3 distinct areas : 1 – the initial area including a potential central area which is the active part of the jet and in which the jet is coherent over about 40 mm as from the nozzle’s outlet. 2 – the main area including :· a continuous flowing area (±100 mm).· another area in which the flowing begins to break up (±150 mm). 3 – the final area including an area in which the flowing becomes mist. As an indication, a pure waterjet is no longer dangerous as from 1000 mm. |
