Analysis of Different Tool Path Strategies for Free Form Machining with Computer Aided Surface Milling Operations

[EN] Free form surfaces are commonly used to generate aesthetic parts. These parts can be manufactured directly by material removal techniques or indirectly with molding or forming techniques. In any case, these surfaces must be commonly machined with traditional processes, at least until certain degree of surface finishing, and the tool path must be generated with computer aided applications. In doing so, developers are implementing new theoretical strategy operations for controlling tool path and trajectories. These new options have so many combinations that it is difficult to know which is the best one to choose when defining the tool movements. Apart from the traditional strategies fixed angle method, principal axis method and multipoint machining, combined with tool orientation, there are many other strategies to explore due to machine tool and numerical control improvements. What is need now is a validation of these new strategies in computer aided applications regarding time minimizing and how the cutting parameters affects in the surface final result.The authors would like to thanks Universitat Politècnica de València, La Fondation Dassault Systèmes, Carolina Foundation and the National Polytechnic School for the support of this article through the 2017 call and project PIS 16-15 - PIS 16-22.Vila, C.; Ayabaca-Sarria, C.; Torres Carot, R.; Gutiérrez, SC.; Meseguer, M.; Yang, X. (2019). Analysis of Different Tool Path Strategies for Free Form Machining with Computer Aided Surface Milling Operations. Procedia Manufacturing. 41:843-850. https://doi.org/10.1016/j.promfg.2019.10.006S8438504

Milling process simulation in micro-scale and experimental study of Al7075-Τ651

Construction of complex mechanical parts requires numerous manufacturing processes. Machined surface quality plays a dominant role in mechanical assemblies as well as in the functionality of each part. Therefore, even a slight process and product quality enhancement offers a competitive advantage to a certain manufacturing industry. Modern research in the field of manufacturing has focused on ball end milling processes. Due to the fact that recently, there is a tendency for small object construction, micro scale cutting processes have become of particular interest.The aim of the present thesis is the development of an integrated ball-nose end milling simulation model in micro scale, along with the investigation of the effect of cutting conditions on both tool and machined workpiece surface quality. The approach incorporated for the process simulation, involves the geometrical representation of the cutting tool and the workpiece followed by the utilization of process kinematics. The main benefits of this approach refer to the precise determination of the machined surface along with the three dimensional representation of the chip, which results in a more accurate cutting force calculation.Within the context of the study, a simulation software that incorporates all stages of the process kinematics implementation, was developed. More specifically, as soon as the three dimensional geometries of the ball end mill and the workpiece are automatically produced, simulation proceeds to the discretized implementation of the process kinematics. As long as the simulation is completed, the three dimensional results are stored on the hard disk drive of the computer. The outcome of the simulation include the resulted surface topomorphy along with the undeformed chip and these data are used for the calculation of surface roughness and cutting forces. A series of experiments was conducted so as to validate the above-mentioned simulated results. Furthermore, an application for the calculation of surface roughness was developed employing an algorithm that calculates the main roughness parameters using the geometric features of the resulted surface. Likewise, the respective application for the calculation of cutting force components was build, based on the undeformed chip geometric features in accordance with Kienzle and Victor. Finally, the regression analysis method was implemented for the determination of equations representing both machined surface roughness and cutting forces in micro-milling process.Η κατασκευή μηχανολογικών τεμαχίων απαιτεί μια σειρά από μηχανουργικές κατεργασίες. Από την άλλη μεριά κυρίαρχο ρόλο στη συναρμολόγηση τεμαχίων αλλά και στη λειτουργικότητα τους διαδραματίζει η ποιότητα της κατεργασμένης επιφάνειας. Έτσι, η παραμικρή βελτίωση της κατεργασίας και της ποιότητας των τελικών προϊόντων, είναι ικανή να δώσει το ανταγωνιστικό πλεονέκτημα στην εκάστοτε βιομηχανία. Για το λόγο αυτόν, τα τελευταία χρόνια η έρευνα στο επιστημονικό πεδίο του φραιζαρίσματος με εργαλεία σφαιρικής απόληξης έχει ενταθεί. Καθ’ ότι στη σύγχρονη περίοδο υπάρχει η τάση για κατασκευή μικρού μεγέθους αντικειμένων, οι κατεργασίες αφαίρεσης υλικού στη μίκρο-κλίμακα αποτελούν τομέα ιδιαίτερου ενδιαφέροντος.Το αντικείμενο της παρούσας διατριβής είναι η ανάπτυξη ενός ολοκληρωμένου μοντέλου προσομοίωσης του φραιζαρίσματος με εργαλείο σφαιρικής απόληξης στη μίκρο-κλίμακα καθώς και η μελέτη της επίδρασης των συνθηκών κοπής, τόσο στο εργαλείο όσο και στην τελική ποιότητα επιφάνειας. Η προσέγγιση που ακολουθήθηκε για την προσομοίωση της κατεργασίας αφορά τη γεωμετρική αναπαράσταση των συμμετεχόντων στην κατεργασία κοπτικού εργαλείου και τεμαχίου, με εφαρμογή της κινηματικής της κατεργασίας. Τα πλεονεκτήματα αυτής της προσέγγισης εντοπίζονται στον ακριβή προσδιορισμό της κατεργαζόμενης επιφάνειας και στην τρισδιάστατη γραφική απεικόνιση του απαραμόρφωτου αποβλίττου κοπής και άρα στον ακριβέστερο υπολογισμό των δυνάμεων κοπής.Για την αυτοματοποίηση των διαδικασιών αναπτύχθηκε λογισμικό το οποίο ενσωματώνει όλα τα στάδια εφαρμογής της κινηματικής της κατεργασίας. Πιο συγκεκριμένα, το λογισμικό σχεδιάζει αυτόματα την τρισδιάστατη γεωμετρία του εργαλείου σφαιρικής απόληξης και του προς κατεργασία τεμαχίου και μέσα από διακριτά βήματα εφαρμόζεται η κινηματική της διαδικασίας. Μετά το πέρας της προσομοίωσης, τα τρισδιάστατης μορφής αποτελέσματα αποθηκεύονται στον ηλεκτρονικό υπολογιστή. Τα αποτελέσματα του μοντέλου περιλαμβάνουν την προκύπτουσα τοπομορφία επιφάνειας και το τρισδιάστατο απαραμόρφωτο απόβλιττο της κοπής, ενώ με κατάλληλη επεξεργασία αυτών των αποτελεσμάτων προκύπτει η τραχύτητα της επιφάνειας και οι δυνάμεις κοπής. Τα αποτελέσματα τραχύτητας και δυνάμεων επαληθεύτηκαν μέσω μεγάλης σειράς πειραμάτων.Για τον υπολογισμό της επιφανειακής τραχύτητας αναπτύχθηκε εφαρμογή και αντίστοιχος αλγόριθμος υπολογισμού των κυρίων παραμέτρων βασισμένος στα γεωμετρικά χαρακτηριστικά της προκύπτουσας επιφάνειας. Αντίστοιχα, αναπτύχθηκε εφαρμογή για τον υπολογισμό των κύριων συνιστωσών των δυνάμεων κοπής, βασισμένη στα γεωμετρικά χαρακτηριστικά του απαραμόρφωτου αποβλίττου, σύμφωνα με τους Kienzle και Victor. Τέλος, με τη χρήση ενός στατιστικού λογισμικού πακέτου εφαρμόστηκε η μέθοδος της ανάλυσης παλινδρόμησης για τον προσδιορισμό εξισώσεων που περιγράφουν, τόσο την προκύπτουσα τραχύτητα επιφάνειας, όσο και τις δυνάμεις κοπής που αναπτύσσονται κατά το μικροφραιζάρισμα

Milling process simulation in micro-scale and experimental study of Al7075-Τ651

Μη διαθέσιμη περίληψηNot available summarizatio

Effluent organic matter (EfOM) characterization by simultaneous measurement of proteins and humic matter

Summarization: This work developed a method, based on the Lowry method and Frølund modification, for the simultaneous determination of proteins and humic matter in wastewater effluent samples at low concentrations. The method was based on simultaneous spectrophotometric measurements of proteins and humic matter at 750 nm in the absence and presence of CuSO4, which is responsible for increasing the absorbance only in the presence of to proteins. Statistical analysis through ANOVA showed that the response surface of the method fit the experimental measurements at significance level lower than 0.05, indicating satisfactory fit. The quantification limits of the proposed method were 0.5-30 mg/l for proteins and 2-30 mg/l for humic matter. The presence of carbohydrates did not interfere with the analysis of proteins and humic matter at carbohydrate concentrations below 35-40 mg/l. The Lowry method overestimated the concentration of the proteins because of the presence of humic substances. A carbon balance indicated that the analytical method developed could provide a satisfactory distribution of the main organic constituents in wastewater and effluents.Presented on: Water Researc

An analytical method for measuring specific endocrine disruptors in activated sludge (biosolids) using solid phase microextraction-gas chromatography

Περίληψη: Occurrence of emerging contaminants in the environment reveals a growing problem, attributed to uncontrolled disposal or insufficient elimination of those pollutants during wastewater treatment. The possession of efficient and competent analytical tools is important in order to examine the root of this problem. In the present study, an analytical method was developed for the determination of selected endocrine disruptors and pharmaceutical compounds in activated sludge (biosolids). The following ten compounds, triclosan, 2,4-dichlorophenol, 2,3,4-trichlorophenol, bisphenol A, estrone, 17-beta-estradiol, 17-alpha-ethinylestradiol, androsterone, 5α-androstan-17β-ol-3-one and 19-norethindrone were examined and finally included in the analytical method described. Target compounds were isolated from sludge by ultrasound extraction followed by solid-phase microextraction (SPME). The desorption of the analytes from the SPME fiber was carried out by gas chromatography, while identification and quantitation was achieved with mass spectroscopy. For the development and validation of the method, sludge standards were created by spiking target compounds in dewatered sludge. The metabolic activity of activated sludge was interrupted without changing the structure of the biomass, in order to imitate real sorption conditions that exist in wastewater treatment plants (WWTPs). Concerning the optimization of the extraction process, several parameters were investigated, including the type of organic solvent used, duration of the ultrasound extraction, purification of the extract. The limits of detection for examined compounds ranged between 4 and 50 ng g-1 (biomass, dry weight). The method was applied for the determination of the selected compounds in sludge samples collected from large scale municipal on the island of Crete (Greece).Presented on: Journal of Environmental Chemical Engineerin

Influence of milling strategy on the surface roughness in ball end milling of the aluminum alloy Al7075-T6

Περίληψη: Surface roughness has an important role in the performance of finished components. End ball milling is used for achieving high surface quality, especially in complex geometries. Depending on the cutting conditions selected for ball end milling, different milling strategies can be applied. The produced surface quality is greatly affected from the selected milling strategy. The present paper examines the influence of the milling strategy selection on the surface roughness of an Al7075-T6 alloy. A number of cutting parameters are tested (axial and radial depth of cut, feed rate, inclination angles φ and ω) in order to perform 96 experiments and their results are processed using regression analysis and analysis of variance. All possible milling strategies are considered (vertical, push, pull, oblique, oblique push and oblique pull) and for each one of them, a mathematical model of the surface roughness is established, considering both the down and up milling. All models are statistically validated and experimentally verified, and can be used within the limits of the investigating cutting conditions. The polynomials produced are of the third order and the statistically most significant parameters are presented.Presented on: Measuremen

A comparative study of removal of endocrine disrupting compounds (EDCs) from treated wastewater using highly crosslinked polymeric adsorbents and activated carbon

Περίληψη: Removal of some EDCs, such as triclosan including its metabolites (2,4-dichloro phenol and 2,3,4-trichloro phenol), estrogens (estrone, 17-β-estradiol and 17-α-ethinyl estradiol) and some pharmaceuticals (clofibric acid, clofibrate, clofibrate methyl ester, carbamazepine) from water and treated wastewater by commercial highly crosslinked polymer adsorbents (Diaion SP207, Diaion SP825, Dowex L493) and activated carbon was investigated using batch adsorption. The analyses of EDCs were performed by solid phase micro-extraction (SPME) coupled with gas chromatography/mass spectrometry. The optimum dosages of polymer adsorbents were in the range 0.2–1.2 g L-1, while the respective values for activated carbon were in the range 0.05–0.2 g L-1. When treated municipal wastewater was used as the water matrix, removal rates of EDCs for activated carbon clearly deteriorated compared with pure water solutions. However, when the synthetic resins were tested in treated effluent, most substances exhibited similar or even higher removals. Polymer adsorbents exhibited good performance for removal of EDCs from water. Their use in biologically treated effluent for EDCs removal is also a viable option. © 2014 Society of Chemical Industry.Presented on: Journal of Chemical Technology and Biotechnolog

Surface topomorphy and roughness prediction in micro-ball-end milling using a CAD-based simulation

Summarization: Ball-end milling is a widely used finishing process in metal cutting. The small size and the complex of metal machining components are the main reasons for implementing milling in microscale. The surface profile and the dimensional accuracy are key factors on the quality of surface of a product. The selection of optimal cutting conditions can be accomplished by utilising simulation models which can involve the kinematics and the strategies of milling processes. Therefore, the analytical prediction of the produced surface quality (topomorphy and roughness) can be reached. The present study indicates a 3D simulation model of ball-end micro-milling process developed in commercial CAD software and its optical and computing results. Micro-milling experiments of Al7075-T6 were carried out in different conditions by the use of a high speed spindle. A computer application was developed to calculate the roughness out of the controlled points of a plane that intersects with the 3D workpiece. The calculated roughness was compared with the measured surface roughness and the surface topomorphy was captured through a stereo microscope.Παρουσιάστηκε στο: International Journal of Machining and Machinability of Material