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| Author(s): |
Cleiton Lazaro Fazolo de Assis
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 2013-09-20 |
| Examining board members: |
Renato Goulart Jasinevicius;
Eduardo Carlos Bianchi;
Hidekasu Matsumoto;
Alessandro Roger Rodrigues;
Adriano Fagali de Souza
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| Advisor: | Renato Goulart Jasinevicius; Alessandro Roger Rodrigues |
| Abstract | |
Micro manufacturing by means of machining presents difficulties, mainly those related to chip formation, since chip thickness become as small as normal material grain size, as well as the cutting edge radius. At such micro cutting operations material microstructure ascends as a very important issue in terms of machining output, i.e. surface roughness, subsurface damages, cutting forces, etc. This research evaluated the effect of the intervention on the metallurgical microstructure of the material on the cutting phenomena inherent in micromachining. The variables investigated were the feed per tooth (ft), cutting speed (vc), micro end-mill diameter (dΦ) and cutting edge radius (re). The materials used in the experiments were a steel two-phase (ferrite-pearlite) with ferritic grain size of 11 µm and similar one with homogeneous microstructure and ultrafine grains (0.7 µm), both low carbon. The mechanism of chip formation, surface finish and surface integrity were investigated and correlated with the studied variables. Two groups of machining experiments were proposed: (1) macro and micro end-milling and (2) microchannels. Overall, the type of machining was the end milling, without using cutting fluid. The machining tests were carried on a CNC machining center. The cutting tools are coated, diameter 16 mm in macro scale of machining, 200 and 800 μm in micro scale. the adequacy of the microstructure of the workpiece material to the reduce the scale of machining generated some favorable aspects to micromachining, such as better finishing (Ssk≈0 e Sku≈3), continuous chip formation and lesser burr formation by reducing the cutting thickness (fz≤re), enabling micromanufacturing applications for low carbon steels, once limited to structures in the civil construction and pieces obtained by mechanical forming. (AU) | |
| FAPESP's process: | 10/06140-0 - Surface integrity evaluation of hard machinability materials in high performance and accuracy milling |
| Grantee: | Cleiton Lazaro Fazolo de Assis |
| Support Opportunities: | Scholarships in Brazil - Doctorate |