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An experimental test part, which was made up of flat, concave, and convex surfaces of variable curvatures, was designed to be fabricated in a four-axis machining center. Aluminum alloy 7075 and titanium alloyTi-6Al-4Vwere used for the fabrication. Within the finishing process, smeared/adhered material was found in some areas of the concave and convex surfaces of the titanium alloy. On the other hand, smeared/adhered material was not found in the aluminum alloy. To characterize the type of defects, the 3D roughness parameters of the surfaces were measured by confocal microscopy, and surface morphology was observed using optical microscopy and scanning electron microscopy. The kinematics of the ball-end milling process was modeled and it was found that the lead and tilt angles between the tool axis and surface normal vector vary continuously, producing transitions between oblique-plunge-push-up milling and oblique-reverse-push-up milling. This causes variation in the thickness behavior during the chip formation process. It was found that the lead angle has a moderate influence, while the tilt angle has a strong effect on the quality of the surfaces of the titanium alloy, with negative tilt angles producing the worst surfaces when there was the oblique-plunge-push-up milling process. [ABSTRACT FROM AUTHOR]

The surfaces of a personalized maxillofacial prosthesis were manufactured in a relatively short period of time and at a moderate cost. The surface topography was generated with a Computer-Aided Design system from the Computerized Axial Tomography of a maxillofacial area. The design of the machining manufacturing process, its simulation and verification, were facilitated by the use of a virtual machine tool equivalent to the real machine tool available. Finally, the manufacturing process was successfully achieved by using a conventional 3- axis vertical machining center equipped with a fourth external rotational axis. Using a 3-axis machine tool with an additional axis is less expensive than using a 5-axis machine. There is abundant literature on machining of free-form surfaces using a 5-axis machine tool, but there are few precedents for the manufacturing of this kind of surface using a 4-axis machine. [ABSTRACT FROM AUTHOR]