Elisabetta Ceretti
University of Bergamo
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Featured researches published by Elisabetta Ceretti.
Materials | 2013
A. Attanasio; M. Gelfi; Annalisa Pola; Elisabetta Ceretti; Claudio Giardini
In the most recent decades the introduction of unconventional machining processes allowed the development of micromachining techniques. In this work, the influence of material microstructures on the micromilling process was investigated. Ti6Al4V alloy was selected as workpiece material since it is a very common material for micro applications and because its duplex microstructure can be easily changed by proper thermal treatments. Four different microstructures (namely bimodal, fully equiaxed, fully lamellar and mill annealed) were obtained through recrystallization annealing treatments carried out at different times and temperatures. The mechanical properties of the samples were assessed by microhardness measurements. Nano-indentations were also performed on single grains to understand how the different hardness of phases and structures present in the Ti6Al4V alloy can affect the micromilling process. Microchannels using two flute flat end mills with a diameter equal to 200 µm were realized on the treated samples. Two different feed-per-tooth values were used during the tests. Cutting force, channel shape and burr dimension were investigated. Morphological and energy dispersive spectroscopy (EDS) analyses were performed on tools by means of a scanning electron microscope (SEM): in this way the phenomena mainly influencing the tool status were also identified. Lower cutting forces and reduced tool wear were observed when working fully lamellar microstructures compared to the other ones.
Archive | 2006
Massimo Callegari; Dario Amodio; Elisabetta Ceretti; Claudio Giardini
In recent years the traditional sheet metal forming processes, suitable for high volume batches, do not correctly meet new market requirements characterised by high flexibility, reduced time-to-market, low cost for small batch production, etc. Moreover, they are not suitable for producing low cost prototypes and pre-series components. Thus new sheet metal forming techniques are very often required and pursued by manufacturing industries and have been intensively undertaken by scientific research groups (Siegert et al., 1997; Amino et al., 2000; Shima, 2001; Kochan, 2001; Shim et al., 2001; Filice et al., 2002; Iseki & Naganawa, 2002; Kim et al., 2003; Yoon et al., 2003; Ceretti et al., 2002, 2004; McLoughlin et al., 2003; Allwood et al., 2005; Lamminen, 2005; Meier et al., 2005). Among the new innovative technologies, the sheet Incremental Forming (IF) can be successfully used for small pre-series batches or prototypes. IF is a process where common and simple tools mounted on CNC machines, instead of complex die sets, are used to deform locally a workpiece. In recent years many studies have been done on IF and many are still in progress with the aim of finding both the most affecting process parameters and the suitable machines and working centres to run experiments and production (Park & Kim, 2002, 2003; Jeswiet et al., 2005a, 2005b; Duflou et al., 2005a, 2005b; Hirt et al., 2005; He et al., 2005a, 2005b; Ambrogio et al., 2005; Bambach et al., 2005). Unlike the standard metal forming process, fast production changes are possible thanks to the very simple IF machine configuration. Even if the time required for making one product is much longer than in the traditional press forming, the IF advantages are gained on tool design and production in prototyping phase. IF could be also successfully applied in completion flexible work cells, for example after hydroforming operations for slots or small parts finishing. Furthermore, instead of using general purpose CNC machines, the modern incremental sheet processes can be directly performed on robotised cells. This will enhance the advantages in flexibility and production time reduction since a robotised cell equipped with the proper tools can produce the part and, on the same fixture, realise the completion operations such as flanging, trimming and so on. To form the sheet into the desired shape an ad hoc tool, mounted on the machine spindle or on a robot gripper, is moved according to the given tool path. Several IF strategies have been developed which mainly differ for equipment and forming procedure. In particular,
AIP Conference Proceedings | 2018
Aldo Attanasio; Elisabetta Ceretti
This paper deals with micro milling cutting process focusing the attention on tool run-out measurement. In fact, among the effects of the scale reduction from macro to micro (i.e., size effects) tool run-out plays an important role. This research is aimed at developing an easy and reliable method to measure tool run-out in micro milling based on experimental tests and an analytical model. From an Industry 4.0 perspective this measuring strategy can be integrated into an adaptive system for controlling cutting forces, with the objective of improving the production quality, the process stability, reducing at the same time the tool wear and the machining costs. The proposed procedure estimates the tool run-out parameters from the tool diameter, the channel width, and the phase angle between the cutting edges. The cutting edge phase measurement is based on the force signal analysis. The developed procedure has been tested on data coming from micro milling experimental tests performed on a Ti6Al4V sample. The ...
ESAFORM 2016: Proceedings of the 19th International ESAFORM Conference on Material Forming | 2016
Luca Giorleo; Elisabetta Ceretti; Claudio Giardini
In Ring Rolling process, to generate a seamless and axis symmetrical ring, two independent deformation processes simultaneously occur to reduce the starting ring cross section shape (width and height) in order to increase the diameter. How this shape changes during the whole deformation process greatly affects the produced ring quality and the loads and energy needed. The main problem is that the shape change is due to two deformation processes that occur in two different ring sections. The ring width reduction is realized in the cross section between the Idle and the Driver roll while the cross section deformed by the Axial rolls movement regulates the ring height. The main problem is that each roll speed law could be set independently from the others. In the industrial environment, a milling curve is introduced to correlate them to the ring section shape. In order to enhance the knowledge on how the Idle and Axial roll speed laws affect the Ring Rolling process, in this work an industrial case study was modeled by a numerical approach. Different Idle and Axial roll speed laws (linearly decreasing, constant, linearly increasing), were designed and simulated. The results were analyzed in order to understand how each speed law trend affects the produced ring quality (higher diameter, lower fishtail) and the process performance (lower loads and energy required for manufacturing).
Archive | 2018
Maria Surfaro; Luca Giorleo; Lorenzo Montesano; Gabriele Allegri; Elisabetta Ceretti; Giovina Marina La Vecchia
The surface of structural components is usually subjected to higher stresses, greater wear or fatigue damage, and more direct environmental exposure than the inner parts. For this reason, the interest to improve superficial properties of items is constantly increasing in different fields as automotive, electronic, biomedical, etc. Different approaches can be used to achieve this goal: case hardening by means of superficial heat treatments like carburizing or nitriding, deposition of thin or thick coatings, roughness modification, etc. Between the available technologies to modify components surface, Laser Surface Texturing (LST) has already been recognized in the last decade as a process, which improves the tribological properties of various parts. Based on these considerations the aim of the present research work was to realize a controlled laser texture on a Diamondlike Carbon (DLC) thin coating (about 3 uf06dm thick) without damaging both the coating itself and the substrate. In particular, the effect of laser process parameters as marking speed and loop cycle were investigated in terms of texture features modifications. Both qualitative and quantitative analyses of the texture were executed by using a scanning electron microscope and a laser probe system to select the proper laser parameters. Moreover, the effect of the selected texture on the DLC nanohardness, adhesion and wear behavior was pointed out.
AIP Conference Proceedings | 2018
Alessandro Colpani; Antonio Fiorentino; Elisabetta Ceretti
Additive Manufacturing (AM) differs from traditional manufacturing technologies by its ability to handle complex shapes with great design flexibility. These features make the technique suitable to fabricate customized components, particularly answering specific custom needs. Although AM mainly referred to prototyping, nowadays the interest in direct manufacturing of actual parts is growing. This article shows the application of AM within the project 3DP-4H&W (3D Printing for Health & Wealth) which involves engineers and physicians for developing pediatric custom-made medical devices to enhance the fulfilling of the patients specific needs. In the project, two types of devices made of a two-component biocompatible silicone are considered. The first application (dental field) consists in a device for cleft lip and palate. The second one (audiological field) consists in an acoustic prosthesis. The geometries of the devices are based on the anatomy of the patient that is obtained through a 3D body scan process. For both devices, two different approaches were planned, namely direct AM and indirect Rapid Tooling (RT). In particular, direct AM consists in the FDM processing of silicone, while RT consists in molds FDM fabrication followed by silicone casting. This paper presents the results of the RT method that is articulated in different phases: the acquisition of the geometry to be realized, the design of the molds taking into account the casting feasibility (as casting channel, vents, part extraction), the realization of molds produced through AM, molds surface chemical finishing, pouring and curing of the silicone. The fabricated devices were evaluated by the physicians team that confirmed the effectiveness of the proposed procedure in fabricating the desired devices. Moreover, the procedure can be used as a general method to extend the range of applications to any custom-made device for anatomic districts, especially where complex shapes are present (as tracheal or maxillary prostheses).Additive Manufacturing (AM) differs from traditional manufacturing technologies by its ability to handle complex shapes with great design flexibility. These features make the technique suitable to fabricate customized components, particularly answering specific custom needs. Although AM mainly referred to prototyping, nowadays the interest in direct manufacturing of actual parts is growing. This article shows the application of AM within the project 3DP-4H&W (3D Printing for Health & Wealth) which involves engineers and physicians for developing pediatric custom-made medical devices to enhance the fulfilling of the patients specific needs. In the project, two types of devices made of a two-component biocompatible silicone are considered. The first application (dental field) consists in a device for cleft lip and palate. The second one (audiological field) consists in an acoustic prosthesis. The geometries of the devices are based on the anatomy of the patient that is obtained through a 3D body scan proces...
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF GLOBAL NETWORK FOR INNOVATIVE TECHNOLOGY AND AWAM INTERNATIONAL CONFERENCE IN CIVIL ENGINEERING (IGNITE-AICCE’17): Sustainable Technology And Practice For Infrastructure and Community Resilience | 2017
Luca Giorleo; Elisabetta Ceretti; Lorenzo Montesano; G. M. La Vecchia
WC/Co coatings are widely applied to different types of components due to their extraordinary performance properties including high hardness and wear properties. In industrial applications High Velocity Oxy-Fuel (HVOF) technique is extensively used to deposit hard metal coatings. The main advantage of HVOF compared to other thermal spray techniques is the ability to accelerate the melted powder particles of the feedstock material at a relatively high velocity, leading to obtain good adhesion and low porosity level. However, despite the mentioned benefits, the surface finish quality of WC-Co HVOF coatings results to be poor (Ra higher than 5u2005µm) thus a mechanical polishing process is often needed. The main problem is that the high hardness of coating leads the polishing process expensive in terms of time and tool wear; moreover polishing becomes difficult and not always possible in case of limited accessibility of a part, micro dimensions or undercuts. Nowadays a different technique available to improve su...
Archive | 2016
Elisabetta Ceretti; Antonio Fiorentino; Claudio Giardini
Hydroforming is a soft tool forming process, where a liquid medium, generally water with a small percentage of added oil, is pressurized and controlled by means of a hydraulic circuit and used to deform the workpiece, either a tube or a sheet, into the final component shape.
1st Int. Conf. On Sustainable Manufacturing, | 2007
Claudio Giardini; Elisabetta Ceretti
40th North American Manufacturing Conference (NAMRC 40) | 2012
Luca Giorleo; Elisabetta Ceretti; Claudio Giardini