Evaluation of the machinability of CW614N brass alloy

Brass alloys are widely used materials for general and industrial applications. However, the lead content in them forces manufacturers to develop new ecological types, the properties of which must be gradually specified in order for the product to be produced and processed more efficiently. The article deals with the evaluation of the machinability of CW614 brass by investigating the influence of technological parameters on the surface roughness of the machined surface and the intensity of vibrations during machining. The measured data were statistically processed; with the help of regression analysis, mathematical formulations of the influence of input parameters on monitored variables were defined and based on them, functional dependencies were plotted in the MATLAB software application. The results showed that at the CW614N brass alloy machining, the feed rate has the greatest influence on the surface roughness Ra, but the depth of cut has the greatest influence on the vibration intensity.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021, 032TUKE-4/2022, SK-CN-21-0046

Tensile fracture analysis of 3D printed Inconel 718

The article deals with the fracture analysis of uniaxial tensile stressed samples made of Inconel 718 alloy by DMLS (Direct Metal Laser Sintering) technology. The samples were heat treated according to AMS 5664 procedure. The material sheet of the EOS Nickel Alloy IN718 provides the tensile properties of the heat-treated samples built only in Z-direction, so the authors decided to also explore the tensile behaviour of the 3D-prinied samples in individual X- and Y-directions. Further to tensile testing, fracture surface observations were performed to identify the principal failure modes. Fractographic investigation on tensile fractures, revealed predominantly a quasi-ductile failure mechanism, showing fine size dimple formation. © 2023 The Authors. Published by Elsevier B.V.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021

Tensile properties of 3D printed INCONEL 718 cellular specimens

The aim of the presented research by the authors was to compare the behaviour of four types of cellular structures under quasi-static tensile stress, while two samples were formed by mono-structures Gyroid 10 % and Diamond 10 %, and the other two types were bi-structures, which were created by combining two single structures (Gyroid 5 % + Gyroid 5 %) and (Gyroid 5 % + Diamond 5 %). The samples were made of Inconel 718 by Direct Metal Laser Sintering technology on an EOS EOSINT M270 machine, and they were heat treated according to AMS 5664 procedure. Tensile tests were performed on an Instron 8802 servo-hydraulic testing machine with a maximum capacity of 250 kN at ambient temperature. The results showed that the maximum load corresponded to the diamond (D) cellular structure (approximately 48 kN), while the minimum load was observed for the gyroid-gyroid (GG) structure (approximately 32 kN)

Effect of crosshead speed and volume ratio on compressive mechanical properties of mono- and double-gyroid structures made of Inconel 718

The current development of additive technologies brings not only new possibilities but also new challenges. One of them is the use of regular cellular materials in various components and constructions so that they fully utilize the potential of porous structures and their advantages related to weight reduction and material-saving while maintaining the required safety and operational reliability of devices containing such components. It is therefore very important to know the properties of such materials and their behavior under different types of loads. The article deals with the investigation of the mechanical properties of porous structures made by the Direct Metal Laser Sintering (DMLS) of Inconel 718. Two types of basic cell topology, mono-structure Gyroid (G) and double-structure Gyroid + Gyroid (GG), with material volume ratios of 10, 15 and 20 %, were studied within our research to compare their properties under quasi-static compressive loading. The testing procedure was performed at ambient temperature with a servo-hydraulic testing machine at three different crosshead testing speeds. The recorded data were processed, while the stress–strain curves were plotted, and Young’s modulus, the yield strength Re0.2, and the stress at the first peak of the local maximum σLocMax were identified. The results showed the best behavior under compression load among the studied structures displayed by mono-structure Gyroid at 10 %. At the same time, it can be concluded that the wall thickness of the structure plays an important role in the compressive properties but on the other hand, crosshead speed doesn´t influence results significantly.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021, 032TUKE-4/2022, SK-CN-21-0046)ELKEME S.A [APVV-19-0550, KEGA 005TUKE-4/2021, KEGA 032TUKE-4/2022

Machinability of Eco-Friendly Lead-Free Brass Alloys: Cutting-Force and Surface-Roughness Optimization

The machinability in turning mode of three lead-free brass alloys, CuZn42 (CW510L), CuZn38As (CW511L) and CuZn36 (C27450) was evaluated in comparison with a reference free-cutting leaded brass CuZn39Pb3 (CW614N), as far as the quality characteristics, i.e., cutting force and surface roughness, were concerned. A design of experiments (DOE) technique, according to the Taguchi L16 orthogonal array (OA) methodology, as well as analysis of variance (ANOVA) were employed in order to identify the critical-to-machinability parameters and to obtain their optimum values for high-performance machining. The experimental design consisted of four factors (cutting speed, depth of cut, feed rate and alloy) with four levels for each factor using the “smaller-the-better” criterion for quality characteristics’ optimization. The data means and signal-to-noise (S/N) responses indicated that the depth of cut and the feed rate were the most influential factors for the cutting force and surface roughness, respectively. The optimized machining parameters for cutting force (34.59 N) and surface roughness (1.22 μm) minimization were determined. Confirmation experiments (cutting force: 39.37 N and surface roughness: 1.71 μm) seem to show that they are in close agreement to the main conclusions, thereby validating the findings of the statistical evaluation performed

Final Heat Treatment as a Possible Solution for the Improvement of Machinability of Pb-Free Brass Alloys

Heat treatment was performed in order to improve the machinability of three lead-free extruded and drawn brasses, namely CuZn42 (CW510L), CuZn38As (CW511L), and CuZn36 (C27450), based on the concept of microstructural modification. The examined machinability criteria were the following: chip morphology, power consumption, cutting force, and surface roughness. All the above quality characteristics were studied in turning mode in “as received” and “heat treated” conditions for comparison purposes. The selected heat treatment conditions were set for CW510L (775 °C for 60 min), CW511L (850 °C for 120 min), and C27450 (850 °C for 120 min) lead-free brass alloys, according to standard specification and customer requirement criteria. The results are very promising concerning the chip breaking performance, since the heat treatment contributed to the drastic improvement of chip morphology for every studied lead-free brass. Regarding power consumption, heat treatment seems beneficial only for the CW511L brass, where a reduction by 180 W (from 1600 to 1420 W), in relation to the as-received condition, was achieved. Furthermore, heat treatment resulted in a marginal reduction by 10 N and 15 N in cutting forces for CW510L (from 540 to 530 N) and CW511L (from 446 to 431 N), respectively. Finally, surface roughness, expressed in terms of the average roughness value (Ra), seems that it is not affected by heat treatment, as it remains almost at the same order of magnitude. On the contrary, there is a significant improvement of maximum height (Rt) value of CW511L brass by 14.1 μm (from 40.1 to 26.0 μm), after heat treatment process performed at 850 °C for 120 min

Χαρακτηρισμός, μηχανισμοί κοπής και κατεργασιμότητα μη μολυβδούχων ορειχάλκων

In recent years, the enforced stricter regulations concerning allowable lead content levels in products, especially for drinking water applications, have encouraged the invention and utilization of innovative solutions, such as the development of lead-free brass alloys.This study was focused on the material characterization, cutting mechanisms (chip breaking), as well as the assessment of the machinability of leaded and lead-free brass alloys, widely used in industrial applications for the fabrication of final brass component (bolts, nuts, hydraulic fittings, valves etc.) by machining.Initially, the influence of microstructure and lead presence on dynamic and static mechanical behaviour was studied. The main purpose of this study was the identification of the emergent microscopic fracture mechanisms, for the better interpretation of cutting behaviour during brass rods‘ turning.In addition, a statistical non-parametric study was implemented for the improvement of the quality characteristics of machining process (Chip Morphology, Power Consumption, Cutting Force and Surface Roughness) of the studied alloys.Finally, a first attempt was pursued pertaining to the redesign of the production process flow, via the realization of experimental heat treatment procedures, which were applied for the alteration of microstructure in order to improve the machinability of the studied brass alloysΠροσφάτως, λόγω της αυστηρότερης νομοθεσίας σχετικά με τα επιτρεπόμενα ποσοστά μολύβδου, κυρίως στα προϊόντα/εξαρτήματα στις εγκαταστάσεις πόσιμου νερού, απαιτείται η χρήση καινοτόμων λύσεων, που αφορούν στην ανάπτυξη και βελτιστοποίηση μη μολυβδούχων ορειχάλκων-υψηλής κατεργασιμότητας, ώστε να αποφευχθούν οι επικίνδυνες επιπτώσεις του μολύβδου στον άνθρωπο και το περιβάλλον.Η εν λόγω διατριβή εστιάζεται στον χαρακτηρισμό, τους μηχανισμούς κοπής (chip breaking) καθώς και την κατεργασιμότητα μολυβδούχων και μη μολυβδούχων ορειχάλκων που χρησιμοποιούνται ευρέως στη βιομηχανία για την κατασκευή εξαρτημάτων (κοχλίες, περικόχλια, υδραυλικοί σύνδεσμοι, βαλβίδες κλπ) μέσω μηχανουργικών κατεργασιών. Αρχικώς, μελετήθηκε η επίδραση που έχει η μικροδομή και η παρουσία του μολύβδου στα αποτελέσματα των δυναμικών και στατικών μηχανικών δοκιμών. Στόχος των παραπάνω δοκιμών είναι η καταγραφή των κυρίαρχων τύπων θραύσης, η οποία πρόκειται να συμβάλλει στην κατανόηση της συμπεριφοράς των ορειχάλκινων ράβδων κατά την κοπή. Στην συνέχεια πραγματοποιήθηκε στατιστική μη παραμετρική μελέτη της κατεργασιμότητας μεταξύ των εξεταζόμενων κραμάτων, για την αριστοποίηση των ποιοτικών χαρακτηριστικών της κατεργασίας (Μορφολογία Αποβλίττου Κοπής, Ισχύς Κοπής, Δύναμη Κοπής και Τραχύτητα Επιφάνειας Κατεργασμένου Δοκιμίου). Τέλος, γίνεται μία πρώτη προσπάθεια ανασχεδιασμού της παραγωγικής διαδικασίας, μέσω πραγματοποίησης κατάλληλων θερμικών κατεργασιών, των μη μολυβδούχων κραμάτων, με στόχο την τροποποίηση της μικροδομής τους προκειμένου να βελτιστοποιηθεί η κατεργασιμότητα σε κοπή

Χαρακτηρισμός, μηχανισμοί κοπής και κατεργασιμότητα μη μολυβδούχων ορειχάλκων

In recent years, the enforced stricter regulations concerning allowable lead content levels in products, especially for drinking water applications, have encouraged the invention and utilization of innovative solutions, such as the development of lead-free brass alloys.This study was focused on the material characterization, cutting mechanisms (chip breaking), as well as the assessment of the machinability of leaded and lead-free brass alloys, widely used in industrial applications for the fabrication of final brass component (bolts, nuts, hydraulic fittings, valves etc.) by machining.Initially, the influence of microstructure and lead presence on dynamic and static mechanical behaviour was studied. The main purpose of this study was the identification of the emergent microscopic fracture mechanisms, for the better interpretation of cutting behaviour during brass rods‘ turning.In addition, a statistical non-parametric study was implemented for the improvement of the quality characteristics of machining process (Chip Morphology, Power Consumption, Cutting Force and Surface Roughness) of the studied alloys.Finally, a first attempt was pursued pertaining to the redesign of the production process flow, via the realization of experimental heat treatment procedures, which were applied for the alteration of microstructure in order to improve the machinability of the studied brass alloysΠροσφάτως, λόγω της αυστηρότερης νομοθεσίας σχετικά με τα επιτρεπόμενα ποσοστά μολύβδου, κυρίως στα προϊόντα/εξαρτήματα στις εγκαταστάσεις πόσιμου νερού, απαιτείται η χρήση καινοτόμων λύσεων, που αφορούν στην ανάπτυξη και βελτιστοποίηση μη μολυβδούχων ορειχάλκων-υψηλής κατεργασιμότητας, ώστε να αποφευχθούν οι επικίνδυνες επιπτώσεις του μολύβδου στον άνθρωπο και το περιβάλλον.Η εν λόγω διατριβή εστιάζεται στον χαρακτηρισμό, τους μηχανισμούς κοπής (chip breaking) καθώς και την κατεργασιμότητα μολυβδούχων και μη μολυβδούχων ορειχάλκων που χρησιμοποιούνται ευρέως στη βιομηχανία για την κατασκευή εξαρτημάτων (κοχλίες, περικόχλια, υδραυλικοί σύνδεσμοι, βαλβίδες κλπ) μέσω μηχανουργικών κατεργασιών. Αρχικώς, μελετήθηκε η επίδραση που έχει η μικροδομή και η παρουσία του μολύβδου στα αποτελέσματα των δυναμικών και στατικών μηχανικών δοκιμών. Στόχος των παραπάνω δοκιμών είναι η καταγραφή των κυρίαρχων τύπων θραύσης, η οποία πρόκειται να συμβάλλει στην κατανόηση της συμπεριφοράς των ορειχάλκινων ράβδων κατά την κοπή. Στην συνέχεια πραγματοποιήθηκε στατιστική μη παραμετρική μελέτη της κατεργασιμότητας μεταξύ των εξεταζόμενων κραμάτων, για την αριστοποίηση των ποιοτικών χαρακτηριστικών της κατεργασίας (Μορφολογία Αποβλίττου Κοπής, Ισχύς Κοπής, Δύναμη Κοπής και Τραχύτητα Επιφάνειας Κατεργασμένου Δοκιμίου). Τέλος, γίνεται μία πρώτη προσπάθεια ανασχεδιασμού της παραγωγικής διαδικασίας, μέσω πραγματοποίησης κατάλληλων θερμικών κατεργασιών, των μη μολυβδούχων κραμάτων, με στόχο την τροποποίηση της μικροδομής τους προκειμένου να βελτιστοποιηθεί η κατεργασιμότητα σε κοπή