Luana Bottini

Surface improvement of fused deposition modeling parts by barrel finishing

Purpose – The purpose of this paper is to study the integration between this technology and barrel finishing (BF) operation to improve part surface quality. Fused deposition modeling (FDM) processes have limitation in term of accuracy and surface finishing. Hence, post-processing operations are needed. A theoretical and experimental investigations have been carried out. Design/methodology/approach – A geometrical model of the profile under the action of machining is proposed. The model takes into account FDM formulation and allows to predict the surface morphology achievable by BF. The MR needed in the model is obtained by a particular profilometer methodology, based on the alignment of Firestone–Abbot (F–A) curves. The experimental performed on a suitable geometry validated geometrical model. Profilometer and dimensional measurements have been used to assess the output of the coupled technologies in terms of surface roughness and accuracy. Findings – The coupling of FDM and BF has been assessed and chara...

Investigation via morphological analysis of aluminium foams produced by replication casting

Foams and porous materials with cellular structure have many interesting combinations of physical and mechanical properties coupled with low specific weight. By means of replication casting it is possible to manufacture foams from molten metal without direct foaming. A soluble salt is used as space holder, which is removed by leaching in water. This can be done successfully if the content of space holding fillers is so high that all the granules are interconnected. One of the main advantages of using the replication casting is a close control of pore sizes which is given by the distribution of particle sizes of the filler material. This contrasts with the pore size distribution of the materials foamed by other processes where a wider statistical distribution of pores is found. On the other hand, the maximum porosities that can be achieved using space holders are limited to values below 60%, whereas the other methods allow for porosities up to 98%. Temperature of the mould and infiltration pressure are critical process parameters: a typical problem encountered is the premature solidification of the melt, especially due to the high heat capacity of the salt. In this work foam properties such as cell shape, distribution and anisotropy and defect presence are investigated by using digital image processing technique. For this purpose replicated AlSi7Mg0.3 alloy foams are produced by infiltrating preforms of NaCl particles, varying the metal infiltration pressure and the mould preheating temperature. An original procedure based on image analysis has been set up to determine size, morphology and distribution of cells. The paper demonstrates that this methodology, coupled with microstructural analysis, is a useful tool for investigating the effects of process parameters on foam properties.

Design of a process for image improvement in digital cytology: a preliminary technology assessement

The work is focused on digital cytology, in particular on the introduction of the e-slides in the e-laboratory of cytology. The study has faced the problem of image-improvement in digital cytology, starting from the settling up of a significant application of digital cytology through the WEB up to the research and application of a suitable software environment. Thirty-eight snapshots have been selected from six e-slides relevant to cervico-vaginal cytology positioned at a web server. The software Mathematica has been selected due to its own characteristics and has been successfully used in a proposed process of image improvement applied on the snapshots with particular attention to (a) the focus emulation; (b) the visibility enhancement and (c) the feature recognition. The proposed methodology has been successfully investigated. It could be useful in tele-consulting, e-learning, in cooperative diagnosis and in the applications of image quality improvements. Furthermore, the methodology could be also usefu...

The focus emulation and image enhancement in digital cytology: an experience using the software Mathematica

The digital pathology is an image-based information environment enabled by computer technology that allows for the management of information generated from an e-slide. It embeds both the field of the digital cytology (D-CYT) and of the digital histology (D-HYST). When coming to D-CYT, basic problems due to the need of the technology emulate the focus function. This leads to an increase in the memory occupancy because a sample must be scanned with different levels of view, the so-called Z-stack. The study focuses on this basic problem in D-CYT. Eighteen snapshots have been selected from three cervico-vaginal e-slides. A table has been compiled with the information of the snapshots by means of coordinates, description of characteristics and objectives. The Mathematica software has been successfully used to improve the diagnostic content of the snapshots with particular attention to the emulation of the focus. The methodology could be useful in tele-consulting and in cooperative diagnosis because it could contemporarily allow the improvement of the diagnostic power combined with a decrease in the memory occupancy of exchanged snapshots.

The e-Slide in the e-Laboratory of Cytology: Where are We?

The work approaches the new technological scenario relevant to the introduction of the e-slide in the e-Laboratory of cytology. A detailed analysis of the state of introduction of the technology based on the e-slides has been conducted. The analysis focused on the ICT technologies available for both the remote diagnosis and the cooperative diagnosis in the Hospital based using the e-slide. In particular the work critically investigated the scenarios of introduction of the e-slides with particular attention to the client/server technologies, the tablet solutions, the 3D Virtual reality solutions. From a global point of view the chapter showed that the today’s technologies using the e-slide have a great potentiality in the digital-cytology.

Estimation of Material Removal by Profilometer Measurements in Mass Finishing

This paper presents a new procedure to estimate the material removal (MR) in such conditions or operations where small amount of material or wear occur. The monitoring of material removal is essential to understand the machining mechanisms of several processes such as super finishing ones. For example the study of some mass finishing (MF) operations, i. e. the barrel finishing (BF) and the spindle finishing (SF), have been always limited by the difficulty to measure the local surface modification. Thus there is no knowledge about the relationship between process parameters and obtainable surface quality. The procedure is based on profilometer measurements typically used to characterized local surface morphology. An algorithm automatically finds the most representative peak of the profile. The comparison between the Abbot-Firestone curves, related to peaks achieved in different condition, permits to measure the volume of material removed by the operation. This method overcomes the well-known problem to repositioning the instrument in the same place when the part is moved from machining process to measurement one. In the case of BF, experimental demonstrated the reliability of this methodology to provide the evolution of material removed as a function of working time. Moreover the graphical plot of the representative peak at different times gave important information about machining mechanism. In particular it allowed to verify assumptions regarding the plastic deformation and the peak cutting which takes place.

Increasing performances of en Ab-46000 by squeeze casting

The evolution of the mold temperature during squeeze casting of EN-AB46000 aluminum alloy has been correlated with the final mechanical performances of cast ingots. Starting from a material model which expresses hardness and yielding stress of cast aluminum alloys as a function of the cooling rate during the melt solidification, an experimental approach has been used to provide a useful tool for process monitoring. As a result, the mold temperature increase during the melt squeezing phase is directly correlated with the main mechanical and microstructural parameters. Experiments were made by squeeze cast small cylinders (14 mm in diameter and 18 mm height) at different values of squeezing pressure, mold pre-heating temperature, and melt temperature. Microscopic observations of the sample sections were made as well as hardness measurements and indentation tests. In conclusion, because of the material solidification, a temperature gradient has been observed in the sample which can be directly related with the aluminum alloy dendrite size and, in turn, with microhardness and yielding stress.