Tham khảo tài liệu 'micromachining techniques for fabrication of micro and nano structures part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Micro Abrasive-Waterjet Technology 209 where A nă2 4 d is the orifice diameter Cd is the discharge coefficient with a typical value of p is the pressure and p is the water density. A normal diagram relating P Q d and p as derived from Eqs. 1 and 2 with Cd is shown in Fig. 2 for a variety of orifice diameters. Knowing any two of the four variables enables determination of the other two. For example if a cutting pressure of 4000 bar is required using a mm orifice it will draw a flow rate of l min and the stream power will be kW green dash-dotted lines . A motor larger than kW must be used due to pump inefficiencies. Fig. 2. Normal diagram of power flow rate and pressure Key components Abrasive-waterjet systems include both hardware and software components. They are integrated to maximize the cutting speed user friendliness and cost effectiveness. Hardware A typical AWJ system includes an AWJ nozzle an abrasive feeding hopper an X-Y traverse a high-pressure pump a motor a PC a catcher and a support tank. Figure 1 illustrates an example of an AWJ system with several key components identified. Depending on the application the catcher tank that also serves as the support for the X-Y traverse which 210 Micromachining Techniques for Fabrication of Micro and Nano Structures usually has a cutting area ranging from about m x m up to 14 m x 3 m or larger. The X-Y traverse on which the AWJ nozzle abrasive hopper and other accessories may be mounted has a position accuracy typically from mm to mm or better. A high-speed waterjet is formed by using a high-pressure pump either a hydraulic intensifier or a direct-drive pump as illustrated in Fig. 3. Early high-pressure cutting systems used hydraulic intensifiers exclusively. At the time the intensifier was the only pump capable of reliably creating pressures high enough for waterjet machining. A large motor drives a hydraulic pump typically oil based that in turn operates the .
