Proceedings of SerbiaTrib '13

area of thecylinders. This ratio usually rangesbetween 1:10 and 1:25 and is a constant. To changethe value of water w pressure, it is necessary tochange the oil pressure inn the hydraulic system.Figure 1. The system components of abrasive water jet cutting machine [3]In order to get a jet of water, whose pressure isapproximately constant,the most commonly duplexreciprocating pump- intensifier (DRP) is used. Thisis actually a complex cylinder which is double-joined with the back towards each other. Whenn theacting pump, with two high pressure cylinders,first cylinder completee stroke, piston rod movesback and compresses the water in the secondcylinder.218Figure 2. Fluctuations of pressure during machiningwith abrasive water jet [4][These cycles are repeated successively. Becausethe water can be compressed 12% under thepressure of 400 MPa, the initial stage of the pistontravel is used to compress the water [4]. Water isnot delivered into the system until the waterpressure reaches the set value. Therefore, theactions of draining water and absorbing water arediscontinuous, and thepressure is fluctuant. Toneutralize the pressure p fluctuations, it is necessaryto install an accumulator behind the intensifier.Figure 2 is a diagram which shows the pressureefluctuations in a conventionall intensifier and the phase-shifted intensifierr cylinders.3. ABRASIVEE WATER JET GENERATEDSURFACEAbrasive water w jet generated surface has acharacteristic appearance and is shown in Figure 3.Curved lines, showing s thee movement of abrasivewater jet through the workpiece material, can beobserved in the Figure 3. The topography of themachined surface and thee appearancee of curvedlines are the most importantmacroscopic propertiesof the surface machined with abrasive water jet.Based on the analysis a of these two characteristicsscanresult in significant informationn about themachining process.Roughness of the surface machined withabrasive water jet increases with increasing depthof cut [5]. Surfaces machined with abrasive waterjet are divided into two areas, fine machining zone(theupper zone) and roughh zone (the lower l zone).Irregularities that occur inn the upper zone of themachined surface are considered as microscopiccirregularities and are in the domain off roughness.Irregularities that occur inn the lower zone of themachined surface have macroscopicdimensions.These irregularities are in the domain of wavinesssin conventionall machining.13 th International Conference C onn Tribology – Serbiatrib’13