Software tool to compute the stability lobes Diagram in milling considering a 3D process model. Enhanced algorithm for lobes trimming.

Yttrium oxide (Y2O3) optical ceramics, pure or doped with rare earth ions, are currently investigated as a promising material for transparent windows, solid-state lasers or refractory components. Y2O3 combines high melting point, transparency in a wide wavelength range, good thermal and optical properties and excellent mechanical and chemical stability. There are several approaches to produce transparent yttria ceramics by using hot pressing (HP), hot isostatic pressing (HIP), spark plasma sintering (SPS), microwave sintering, or vacuum sintering. Sintering using high pressures (HP, HIP, SPS) allows decreasing the consolidation temperature and recrystallization rate due to considerable activation of volume diffusion and creep. However, the high cost of the equipment and significant operational expenses restrict the application of sintering under high pressures. An alternative approach to fabricate Y2O3 transparent ceramics is sintering without applying high pressures, such as vacuum sintering. In order to increase sintering activity and reduce consolidation temperatures, very fine powders (submicron- to nanopowders) with high surface energy are required. The powder characteristics (particle size, morphology or specific surface area) determine the sintering behavior and, as a consequence, the possibility and conditions required for the achievement of transparency of ceramics. However, it should be noted that the effect of different starting powders on the processability of Y2O3 transparent ceramics has not been studied in detail in the current literature. This project is focused on the powder treatment of Y2O3 and the production of transparent ceramics: a number of commercial powders with suitable morphology will be selected for the study of the effect of milling parameters on the morphology and sinterability of the powders, eventually with the use of sintering aids. The proposed activities plan includes: 1.Characterization and selection of starting Y2O3 powders (determination of their morphology by SEM, specific surface area, etc.); 2.Milling tests: study of the variation of process parameters (milling speed and time, milling media size); 3.Characterization of the milled powders; 4.Shaping of powders by pressing and sintering in vacuum; 5.Characterization of sintered ceramics (optical properties, microstructure). Depending on the results (transmittance) and the time available, the use of a sintering aid may be considered for one selected powder. The aim of this study is to provide practical information related to the selected powders, and to make more general considerations, linking the microstructure and the type of defects in the sintered ceramics to the process parameters and powder characteristics.

Surface characteristics and machining performances of micro-pockets manufactured by ?EDM as a function of different process conditions are studied in this paper. The micro-pockets were obtained using different combinations of process parameters on different ultra-high temperature ceramics (UHTCs) with the same base matrix (ZrC) and different volume fraction of the second phase (MoSi). This work presents an analysis of the process performances with different machining approaches, from pre-roughing down to fine-finishing. Microstructure analysis of the as-sintered and machined materials was conducted to identify materials modification due to the electrical discharges. A removing material mechanism during the ?EDM process has been hypothesized, correlating the ED-machined surface structure and the main process performances.

We introduce a pipeline for simplifying digital 3D shapes and fabricate them using 2D polygonal flat parts. Our method generates shapes that, once unfolded, can be fabricated with CNC milling machines using special tools called V-Grooves. These tools create V-shaped furrows at given angles depending on the shape of the used tool. Milling the edges of each flat facet simplifies the manual assembly, which consists only in folding adjacent facets at a constrained angle. Our method generates simplified shapes where every dihedral angle between adjacent facets belongs to a restricted set, thus making the assembly process quicker and more straightforward. Firstly, our method automatically computes a simplified version of the input model, using the marching cubes algorithm on the original mesh and iteratively performing local changes on the resulting triangle mesh. The user can then perform an additional manual simplification to remove unwanted facets. Finally, an unfolding algorithm, which takes into account the thickness of the material, flattens the polygonal facets onto the 2D plane, so that a CNC milling machine can fabricate it from a sheet of rigid material.

We introduce here a pipeline for simplifying digital 3D shapes with the aim of fabricating them using 2D polygonal flat parts. Our method generates shapes that, once unfolded, can be fabricated with CNC milling machines using special tools called V-Grooves. These tools make V-shaped furrows at given angles depending on the shape of the used tool. Milling the edges of each flat facet simplifies the manual assembly that consists only in folding the facets at the desired angle between the adjacent facets. Our method generates simplified shapes where every dihedral angle between adjacent facets belongs to a restricted set, thus making the assembly process quicker and more straightforward. Firstly, our method automatically computes a simplification of the model, iterating local changes on a triangle mesh generated by applying the Marching Cubes algorithm on the original mesh. The user performs a second manual simplification using a tool that removes spurious facets. Finally, we use a simple unfolding algorithm which flattens the polygonal facets onto the 2D plane, so that a CNC milling machine can fabricate it with a sheet of rigid material.

Design of the components of the work cell: flanges for different mounting configurations, sensor mounting structures, workpiece clamping systems, spindle holder, calibration tools. Setup of the work cell for testing purpose.

This work is aimed at producing Al-matrix nanocomposites through the powder metallurgy (PM) process. An initial study on pure aluminum powder was performed to analyze the performance of different PM techniques. In particular, Al powder was refined via high-energy ball milling and consolidated by hot extrusion and equal channel angular pressing. The latter revealed to be a very efficient procedure for powder compaction (high density and hardness of the products) and it was adopted for the production of Al-based composites reinforced with 2% and 5 wt% of Al2O3 nanoparticles. The composites exhibited higher hardness than the pure aluminum sample.

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Nanometric powdered TixTa1xC0.5N0.5-based cermets were fabricated using a mechanically induced selfsustaining reaction and consolidated by spark plasma sintering. Highly dense cermets were obtained, and their chemistry, microstructure and mechanical properties were characterised by X-ray diffraction, scanning electron microscopy, image analysis, microindentation and nanoindentation. The microhardness was found to depend directly on the contiguity and size of the ceramic hard particles. The samples synthesised at the lowest temperature (1150 C) exhibited more homogeneous microstructures and smaller ceramic particles and the best combination of microhardness and fracture toughness

Down milling tests were carried out in order to determine the flank wear of two cutting edges of different insert. The material employed in the cutting experiments was Inconel 718. The tests were conducted in dry conditions.

Down milling tests were carried out in order to determine the flank wear of two cutting edges of each different insert. The material employed in the cutting experiments was Ti6Al4V. The tests were conducted in dry conditions.