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Course of ADVANCED MANUFACTURING PROCESSES Proff. Michele Monno – Barbara Previtali – Matteo Strano SURNAME NAME PERSONAL ID Exam 3rd July 2015 Exercise n. 1 – scientific article comprehension You are a production engineer in a company of the energy sector. A new job arrived consisting in the grooving of some channels for micro -fluidic applications alumina AD96- type sheets 6 mm thick ; each channel is 1.1 mm wide and 2 mm deep with a total length of 490 mm . Moreover, at each end point of the trach there is a through hole of 1.1mm in diameter again (see Figure 1 below) . These kind of very hard materials can be milled by means of waterjet, which means that in this case the jet is not passing through the whole thickness but it just remove s a specific layer of material (as shown in Figure 1 of the article). Figure 1: scheme and dimensions of the piece to be machined. Therefore you decide to use a water jet cutting system providing a maximum working pressure of 300 MPa. In order t o design the process, you decided to u se a combination of well -known theoretical equations in combination with an erosion model specific for the milling of polycrystalline ceramics (J. Zeng et al. (1996): “An erosion model for abrasive waterjet milling of polycrystalline ceramics”) Table 1 summarizes the process parameter you decide to use and Table 2 presents the main material characteristics. Table 1: process parameter Parameter Value UDM Pressure, P 270 MPa Coefficient of discharge, C d 0.7 - Coefficient of velocity, C v 0.98 - Water density, ρ w 1000 kg/m3 Primary orifice diameter, d 0 0.33 mm Focuser diameter, d j 1.1 mm Abrasive mass flow rate, m a 400 g/min Abrasive density, ρ a 4100 kg/m3 Abrasive average particle diameter, dp 180 μm considering the particle spherical Table 2:…