Search results for "machining"
showing 10 items of 180 documents
Surface finish on hardened bearing steel parts produced by superhard and abrasive tools
2007
New technological process consisting of hard turning (HT) followed by abrasive machining, in place of the widely used method in industry, i.e., hard turning versus grinding, has lately been launched in the automotive industry. This is because, many transmissions parts, such as synchronizing gears, crankshafts and camshafts require superior surface finish along with appropriate fatigue performance. This paper provides a comprehensive characterization of part surface finish produced in dry turning of a hardened AISI 52100 bearing steel using mixed ceramic (MC) and PCBN tools, and also its modification after special abrasive finishing operations including superfinishing (SF) and belt grinding …
A Study on the Correlations between Machining Parameters and Specimen Quality in WEDM
1999
Wire electrical discharge machining (WEDM) is widely used in manufacturing, medical, aircraft applications and, virtually, all areas of conductive material machining. The process involves a series of very complex electrical, thermodynamical and electromagnetical phenomena that are still partially unknown. Due to the large amount of parameters involved in the process, a suitable set-up of the variables aimed to obtain the best performance is often very difficult. In the paper the results of a wide experimental analysis are presented: the tests were carried out on high-speed steel and tempered steel specimens utilising brass wires. The influence of the most important process parameters on the…
Influence of Material-Related Aspectsof Additive and Subtractive Ti-6Al-4VManufacturing on Energy Demandand Carbon Dioxide Emissions
2017
The additive manufacturing of metal parts represents a promising process that could beused alongside traditional manufacturing methods. The research scenario in this field isstill largely unexplored, as far as the technological solutions adopted to integrate differentprocesses are concerned and in terms of environmental and economic impact assessment.In this article, an electron beam melting (EBM) process and a machining process have beenanalyzed and compared using a cradle-to-grave life cycle–based approach. The productionof components made of the Ti-6Al-4V alloy has been assumed as a case study. Theproposed methodology is able to account for all of the main factors of influence on energydem…
Electroanalytical chemistry for the analysis of solids: Characterization and classification (IUPAC Technical Report)
2012
Solid state electroanalytical chemistry (SSEAC) deals with studies of the processes, materials, and methods specifically aimed to obtain analytical information (quantitative elemental composition, phase composition, structure information, and reactivity) on solid materials by means of electrochemical methods. The electrochemical characterization of solids is not only crucial for electrochemical applications of materials (e.g., in batteries, fuel cells, corrosion protection, electrochemical machining, etc.) but it lends itself also for providing analytical information on the structure and chemical and mineralogical composition of solid materials of all kinds such as metals and alloys, variou…
Etude d'un emmanchement fretté compte tenu de l'effet combiné des défauts de forme et d'état de surface
2012
The main purpose of this thesis is to present two contributions in the field of shrink fitassembly taking into account the defects of form and roughness surfaces. The first contributionconcerns the study of the influence of the defect forme on the characteristics of shrinked assemblyusing an approach based on finite element modeling. We found that this defect has a significantinfluence on the resistance of the assembly. The work already done in the laboratory of mechanicsat the University of Bourgogne have been confirmed. In the second contribution, we proposed tointegrate the surface defects (roughness) by creating a homogenized finite element interface. Thistechnique has facilitated the m…
On Fixed Point (Trial) Methods for Free Boundary Problems
1992
In this note we consider the trial methods for solving steady state free boundary problems. For two test examples (electrochemical machining and continuous casting) we discuss the convergence of a fixed point method. Moreover, using the techniques of shape optimization we introduce a modification of the method, which gives us superlinear convergence rate. This is also confirmed numerically.
Parallel laser micromachining based on diffractive optical elements with dispersion compensated femtosecond pulses
2013
We experimentally demonstrate multi-beam high spatial resolution laser micromachining with femtosecond pulses. The effects of chromatic aberrations as well as pulse stretching on the material processed due to diffraction were significantly mitigated by using a suited dispersion compensated module (DCM). This permits to increase the area of processing in a factor 3 in comparison with a conventional setup. Specifically, 52 blind holes have been drilled simultaneously onto a stainless steel sample with a 30 fs laser pulse in a parallel processing configuration.
Shaping graphene with optical forging: from a single blister to complex 3D structures
2020
Properties of graphene, such as electrical conduction and rigidity can be tuned by introducing local strain or defects into its lattice. We used optical forging, a direct laser writing method, under an inert gas atmosphere, to produce complex 3D patterns of single layer graphene. We observed bulging of graphene out of the plane due to defect induced lattice expansion. By applying low peak fluences, we obtained a 3D-shaped graphene surface without either ablating it or deforming the underlying Si/SiO2 substrate. We used micromachining theory to estimate the single-pulse modification threshold fluence of graphene, which was 8.3 mJ cm−2, being an order of magnitude lower than the threshold for…
An Experimental Investigation of Residual Stresses in Hard Machining of AISI 52100 Steel
2011
In this paper an experimental investigation was conducted to determine the effects of the tool cutting-edge geometry, workpiece hardness, cutting speed, and microstructural changes (white and dark layers) on the residual stresses in dry orthogonal hard machining of AISI 52100 steel. X-ray diffraction technique was used to obtain in-depth residual stresses profiles in both axial and circumferential directions. The results show that tool geometry, workpiece hardness and cutting parameters significantly affect the surface residual stress, maximum compressive residual stress below the machined surface and its location. Moreover, microstructural analysis shows that thermally-induced phase transf…
On the finite element simulation of thermal phenomena in machining processes
2007
Machining processes are frequently investigated by numerical simulations. Usually 2D analyses are carried out in order to reduce CPU times, considering orthogonal cutting conditions. In this way, the computational time sharply reduces and many process variables may be calculated (i.e. forces, chip morphology, shear angle, contact length). On the other hand, the analysis of thermal aspects involved in machining, for instance the temperature distribution reached in tool, still represents an open problem. Finite element codes are able to simulate a very short process time that is not sufficient to reach steady state conditions. Several approaches have been proposed to overcome this problem: in…