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Brass alloys assign a considerable portion of the industrial components\" material due to their outstanding characteristics. These materials are manufactured using hot forging or extrusion techniques, according to the application for different purposes. In this work, the metallographic and mechanical characteristics of three environmentally friendly brass alloys - CuZn40Pb2 (CW617N), CuZn38As (CW511L) and CuZn21Si3P (CW724R) - extruded and multi-directionally hot forged have been examined. By focusing on the flat bottom drilling operation, the effects of the process and type of alloying have been investigated. The examination has been accomplished on experimental data about tensile strength, impact fracture energy, cutting forces, entrance and exit burr diameters, as well as hole quality. The findings demonstrate that the most crucial criteria impacting the machining outcomes are the presence of limited Pb element and material microstructural phases, their content and mechanical characteristics, as well as the type manufacturing process.

The approved restrictive rules on the containment of Lead element in the chemical composition of the brass alloys which are utilized in drinking water and pumping systems have resulted in developing of new material generations. Neglection or limitation of this element has faced the industry with some serious problems such as lower machinability as compared to the conventional ones. Furthermore, since the most application of the manufactured components from these alloys corresponds to the fluids transfer, the permeability property between the parts and their surface becomes prominent. In other words, any burrs or extra material which are left on the surfaces of manufactured components will make assembly troublesome, causing seals to tear, and permeability problems in the user's hands. In this study, the quality of the machined blind holes with flat bottom drills with various geometries including radial, axial rake angle as well as the cutting edge-radius have been investigated for machining of low-lead brass alloy. Moreover, it has attempted to develop fuzzy logic and regression models in order to predict the machined holes burr height and surface quality. The model predictions have been compared with the experimental data. The obtained results have demonstrated that the developed models are able in predicting of the product quality.

The machining of nickel and titanium-based superalloy components is very expensive and involves unusually high lead times compared with other engineering metals such as steels and aluminum. This has led to the development of most suitable additive manufacturing (AM) processes to fabricate these difficult-to-machine metals into near-net shape parts, thereby reducing the lead time and material waste, and significantly increasing productivity. Nonetheless, finish machining is still required on the AMed metal components to meet the dimensional and surface requirements of the application. Several research studies have investigated the machinability of AMed nickel and titanium alloy workpieces and have compared the results with the machining responses of wrought counterparts, which is detailed in this review. The categorization of the literature is based on the machining operations including turning, milling, drilling, and non-conventional machining, and the observations are discussed in accordance with various input parameters such as workpiece characteristics (hardness, microstructures) and anisotropy in mechanical properties due to build orientations during the AM process. Moreover, the influence of these parameters on cutting forces and temperatures, chip formation, and tool wear is analyzed and reported. From this review, it is found that the machinability of AMed nickel and titanium workpieces is quite different to the machining responses of their wrought counterparts. Further thorough experimentation is required to develop optimized machining parameters for AMed metal parts, while an exploration of different cutting tool geometries, coolant, and lubrication strategies for enhanced tool performance for machining AMed workpieces is essential. Finally, this study reviews the state of contemporary research, and offers suggestions for future research.

Purpose The present study aims to investigate the effect of finish machining and aging processes on the surface integrity of the selective laser melted (SLM) maraging steel samples and compared them with those obtained conventionally. Design/methodology/approach Finish machining and aging were applied on the SLM and wrought maraging samples to investigate and compare their microstructural and mechanical properties such as surface roughness, microhardness and wear resistance. Findings After applying aging and finish machining treatments, the surface roughness Originality/value The knowledge of post-processing is essential to enhance the functional performance of the SLM samples. Aging and finish machining were applied for the first time to evaluate the surface integrity of the SLM prepared maraging steel and compared it with the wrought samples.

© 2020 Taylor & Francis Group, LLC.As industries are increasingly adopting the laser powder bed fusion (LPBF) additive manufacturing (AM) process, it is crucial to understand the process closely and to find ways to improve the final quality of the finished parts. The LPBF process is capable of producing tailored designs, which are lighter in weight and having strength comparable to conventional components. However, the acquired surface texture and some of the mechanical properties of LPBF-produced components are still sub-standard compared to the conventional components. As of now, the post-processing technique is witnessed as the only sustainable approach to enhance the mechanical and microstructural performance of the additive products since any further optimization of the LPBF processing parameters is reported inefficient in bringing the relevant changes in the as-built LPBF parts. So far, several post-processing techniques such as thermal, mechanical, and/or chemical-based have been applied to different additive materials, and the results have been beneficial. This article reviews the effects of post-processing operations on the surface integrity properties of as-built LPBF parts, namely surface roughness, microhardness, microstructure, mechanical strength, corrosion, and wear resistance. The results of the post-processing operations are also discussed and compared with the as-built and conventional conditions for different engineering materials.

Austenitic 316LVM stainless are widely used in biomedical industry in particular medical surgical applications, and implant materials. In biomedical applications, especially implants used in the body are exposed to tribological conditions that cause wear behavior. Wear behavior of Implants fabricated by using these materials related to the surface conditions. One of the important processes influencing the surface properties used in fabricating process of implant is machining operation. For this reason, the effect of machining parameters and condition on the surface properties of this material and eventually altering the wear response is the focus of this current research. In this paper, dry milling operations of Austenitic 316LVM under various parameters were presented. The surface roughness, microhardness, microstructure are the examined surface integrity characteristics in this study. The effect of generated characteristics resulting from machining on wear resistance is measured using pin-on-disc test It was revealed that cutting speed and feed has notable effect on surface roughness and strain hardening of the specimen. Increased strain hardening generally results in decreased wear resistance while increased surface roughness results in increased wear resistance.

Rapid heating, melting, solidification and cooling cycles generates high residual stress in additively manufactured parts, causes to part distortion. Finite Element Method (FEM) is one of the common and practical ways to predict residual stress and distortion taking place during additive manufacturing. Thus, it is possible to determine appropriate parameters to eliminate such problems. In this study, laser powder bed fusion (LPBF) additive manufacturing (AM) of Inconel 718 alloy is considered for simulation. Case studies on the residual stress and distortion of arch-shaped structure parts were presented through comparing the simulation results in present study and experimental data borrowed from the literature. The influence of laser scanning parameters such as laser power, scanning speed, layer thickness, scanning strategy on residual stress and distortion of the arch-shaped structure was investigated and compared with the borrowed experimental results. Besides, the influence of heat treatment on residual stress and distortion is also simulated and predicted results are presented. This study reveals that the presented FEM based simulation is capable of capturing experimental data reasonably well.

Machinability, stable productivity, and quality of the components are crucial factors in manufacturing industry. In industrial applications, when cutting parameters and conditions are determined considering experiences gained by engineers which does not resolve the whole problems faced with in case cutting tools and their geometries are involved. Thus, it requires further knowledge that is built through systematic and scientific research. This study presents the results of an experimental investigation of a drilling process of hot forged lead-free brass alloys by using a form cutting tool. Experimental data on cutting forces, dimensional accuracy, and surface quality of the holes is presented considering the tools with different geometries, feed rates and rotational speeds on hot forged lead-free brass alloys with various copper content. Artificial neural networks modelling, and genetic algorithm-based optimization methods have been used to predict and optimize the machining process and related responses. The computational results demonstrated that the developed model and optimization procedure can notably improve the efficiency of the process by reducing the production cost with the obtained optimum machining conditions.

One of the commonly used additive manufacturing methods is extrusion-based 3D printing (e.g., fused filament fabrication or FFF) that is generally required post-processing to make fabricated components ready to be used. This paper considers two major points to assess the surface enhancement of components made of polylactic acid (PLA) material. One is the role of processing parameters including layer thickness, print speed, and printing temperature on dimensional and surface quality of fabricated parts. The second one is post-processing and its parameters. Vibratory surface finishing (VSF) is used as post-processing operation, and treatment time is varied to observe its effect on the surface and dimensional variation of the fabricated parts. The effect of input variables on measured outputs is also presented by using statistical approaches including regression and analysis of variance. This study reveals that layer thickness is dominating parameter to control surface and dimensional quality of both as-printed and post-treated samples. However, printing temperature also plays a notable role on the dimensional accuracy of specimens. Considering post-processing, while it is notable, duration is the key factor determining the final surface quality of fabricated samples. The surface roughness of as-printed samples was reduced by 66% through post-processing operation.

Burnishing has been increasingly utilized to improve the surface integrity of manufactured components. The generation of surface and subsurface layers with ultrafine grains, attributed to severe plastic deformation (SPD) and dynamic recrystallization (DRX), leads to improved surface integrity characteristics including surface and subsurface hardness and reduction in surface roughness. Additionally, due to the generation of compressive stresses within the refined layers, increase in fatigue life and improved wear and corrosion resistance can be achieved. In this study, we apply cryogenic burnishing on Al 7050-T7451 discs and compare the surface integrity characteristics with dry conventional burnishing. A special roller burnishing tool with flexible rotating roller head was designed and used to perform the cryogenic burnishing experiments using liquid nitrogen as the coolant. The results show that cryogenic burnishing can increase the surface hardness by an average of 20–30% within a layer depth of 200 µm compared with only 5–10% increase using dry conventional burnishing. Refined layers with nano grain structure were also generated. During cryogenic burnishing, the tangential burnishing forces were higher than those of dry conventional burnishing due to rapid cooling and work hardening of the material.

Micro-milling is a micro-mechanical cutting method used to obtain complex and three-dimensional micro geometries. Micro-cutting tools are used in the manufacturing of micro-components and the type of workpiece is also important for good surface quality and minimum burr. In this study, micro machinability of Ti6Al4V alloy which is used most frequently in micro-component production is compared with Ti5553 alloy. Micro-milling of Ti5553 alloy and comparison of the minimum chip thickness with Ti6Al4V were performed for the first time in this study. Using different cutting parameters, the variation of surface roughness, burr width, and cutting forces were investigated. The cutting tests were carried out on a specially designed and high-precision micro-milling test system using a TiCN-coated two-flute end mill of 0.6 mm diameter. According to the results, minimum chip thickness is approximately 0.3 times the edge radius of the cutting tool and does not vary with the alloy type. At feed rates smaller than the minimum chip thickness, both the cutting forces increase and the surface quality decreases. For both alloys, reduced feed rate and increased depth of cut lead to increased burr width. The burr widths in Ti6Al4V alloy are higher. At the end of the study, the limits of the cutting parameters where plowing occurred for the both alloys are clearly determined. In addition, the limits of the cutting parameter causing plowing have been confirmed by cutting forces, surface roughness, and burr formation.

Titanium Ti-5553 alloys have been considered asdifficult-to-machine materials due to the extremely high tool wear, highcutting forces, high temperature, and poor surface quality of machined parts.Process parameters needs to be optimized in order to improve machiningperformance and in the meantime reducing manufacturing cost. This study proposessustainable machining process for this new generation Titanium Ti-5553 alloy.Process parameters including depth of cut, cutting speed, and feed rate weretaken into account to optimize parameters for reducing tool wear, energyconsumption, and surface roughness, and in the meantime increase materialremoval rate. Genetic algorithm was utilized for optimizing the processparameters. Obtained results illustrated that optimization using geneticalgorithm is a very effective approach to substantially improve machiningperformance of this alloy and make machining process of this alloy moresustainable by reducing energy consumption, manufacturing cost and increasingmaterial removal rate in machining process of new generation titanium alloy., Çok yüksek takım aşınması,yüksek kesme kuvvetleri, yüksek sıcaklık ve işlenmiş parçaların düşük yüzeykalitesi nedeniyle, Titanyum Ti-5553 alaşımları işlenmesi zor malzemelerdenbiri olarak kabul edilmiştir. Malzemenin işleme performansını artırmak ve buarada üretim maliyetini düşürmek için proses parametrelerinin optimize edilmesien önemli araştırmaların başında gelir. Bu çalışma, bu yeni nesil TitanyumTi-5553 alaşımı için sürdürülebilir bir işleme süreci önermektedir. Takımaşınmasını, enerji tüketimini ve yüzey pürüzlülüğünü azaltmak ve bu sıradatalaş kaldırma oranını artırmak için kesme derinliği, kesme hızı ve ilerlemehızı gibi proses parametreleri optimize edilirken kesme hızı, ilerleme oranı vekesme derinliği dikkate alınmıştır. Proses parametrelerinin optimize edilmesiiçin genetik algoritma kullanılmıştır. Genetik algoritma kullanarak yapılanoptimizasyon sonucu elde edilen değerler, bu alaşımın işleme performansınıbüyük ölçüde iyileştirmek ve işleme sürecinin enerji tüketimini, üretimmaliyetini düşürmekle birlikte yeni nesil titanyum alaşımının talaşlı imalatsürecindeki talaş kaldırma oranını artırarak daha sürdürülebilir hale getirmekiçin çok etkili bir yaklaşım olduğunu göstermiştir.

The present study focuses on the effects of cutting speed, feed rate and cutting tool material on the machining performance of carbon graphite material. Polycrystalline Diamond (PCD) cuttin...

This study presents the results of an experimental investigation on the effect of drilling process on surface integrity characteristics of lead-free brass alloy. Experimental data on dimensional accuracy and the surface quality of the holes, subsurface characteristics including microhardness and microstructure is presented and analyzed to evaluate surface integrity of machined specimens. This study demonstrates that cutting tools has strong influence on both microstructural aspects of lead-free alloy and resulting to hardening of the surface and subsurface along with deformation twinning.

Phase transformation and shape memory response of NiTi alloys are sensitive to the variation of temperature and stress. Thus, the phase transformation of NiTi alloys becomes more complex during machining process. This study presents findings from a major study involving modelling of machining-induced phase transformation of NiTi alloys performed by modifying Helmholtz free energy-based microstructure model. Orthogonal cutting tests were performed to validate the predicted outputs from the simulation, such as cutting forces, temperatures and chip morphology. This work provides a strong evidence that the developed new model can accurately predict the experimentally recorded outputs in machining of NiTi alloys.

This experimental study presents the effects of various post-processes including finish machining (FM), drag finish (DF) and vibratory surface finish (VSF) on surface characteristics and wear performance of Inconel 718 specimens fabricated by selective laser melting additive manufacturing. Concentrated characteristics are surface roughness, surface topography, microstructure, microhardness, XRD pattern and wear resistance. Analysis shows that partially melted powders on the surface and just beneath the surface create an undesired layer and its thickness varies from 80 to 130 µm that leads to poor surface topography and very high surface roughness. FM and DF post-processes are capable of completely removing this layer and in the meantime, up to 96 and 88% lower surface roughness. Post-processes particularly FM leads to occur strain hardening and resulted in up to 21% increase microhardness as compared to as-built material. XRD pattern of as-built and wrought alloys shows substantial difference when considering (111) and (200) planes. This study demonstrates that post-processes enhance the wear performance of SLM manufactured Inconel 718. Coefficient of friction and the wear rate of the as-built specimen decreased more than 10% after FM process.

The reinforcements of nanoparticles have an important role in improving the machinability of nanocomposite materials. Except for the known nanoparticles such as carbon nanotube, graphene, nanoclay, etc., the effect of boron nitride reinforcement on the machinability of composite materials are a recent research topic. In this study, boron nitride nanoparticle was introduced to the matrix resin that brings about additional strength and enhancement in thermal and mechanical properties of the composite. Though it was confirmed that this composition enhances the focused properties, it is necessary to investigate drilling performance of these composite and identify the effects of this boron nitride nanoparticle on machinability of carbon fiber epoxy nanocomposite considering thrust force, delamination factor, etc. Accordingly, while the thrust force is increased by reinforcement of the boron nitride nanoparticles, on the contrary of literature, delamination factor is tend to reduce as compared with reference composite. This experimental study shows the addition of boron nitride nanoparticles help to reduce delamination factor of carbon fiber epoxy nanocomposite. In addition, hole surfaces and drilling mechanism analyzed with optical and scanning electron microscope about damage estimation. © The Author(s) 2019.

Extreme tool wear resulting in short tool life is one of the main issues in the cutting process of near-beta Ti alloys. This study provides extensive experimental results and new findings that help to understanding progressive tool wear and the corresponding measures in high speed machining of Ti-5553 alloy under various coolant and lubrication (dry, flood, high-pressure coolant, MQL, and Cryogenic cooling) conditions at finish and semi-finish cutting. Cutting temperature, progressions of tool wear, and tool life are presented. Besides, cutting forces, frictional conditions, and chip morphology are studied. This current work provides evidence that supports the argument that the feasibility of high speed machining of near-beta titanium alloys that depends on cutting conditions, namely coolant and lubrication used during machining. It was found that tool wear is developed by an abrasive and adhesive mechanism, and built-up-edge formation is a common problem in the machining of this alloy. A high pressure coolant supply with its cooling and lubrication ability was found to be very helpful for decreasing the coefficient of friction and temperature during the process, consequently lowering progression of wear and cutting force components when compared to other cooling and lubrication conditions tested in this study. The greatest tool life is achieved by high-pressure coolant supply, and cryogenic cooling achieves the second greatest tool life. Minimum quantity lubrication is found to be inefficient for improving the machining performance of this alloy. Finally, it is found that the selected depth of cut has vital effect on the penetration capability of cooling and lubrication in between tool and chip, and consequently, it plays a significant role in the contribution of cooling and lubrication to the machining performance of this alloy.

Metal additive manufacturing is an emerging method to fabricate components used in the aerospace and biomedical industries. However, one of the significant challenges in this approach is the surface quality of the fabricated components. After metal additive manufacturing operations, post-processing is essential to meet the expected surface quality. This study presents the surface characteristics of as-built specimens manufactured by selective laser melting (SLM), where improvement of the surface can be achieved by post-processing operations. The post-processing operations in focus are finish machining (FM), vibratory surface finishing (VSF) and drag finishing (DF) operations. Surface topography, average surface roughness, microhardness, microstructure and XRD analysis have been carried out to examine the surface characteristics resulting from the post-processing operations. This study demonstrates that the drag finishing operation can be used for post-processing to meet the surface quality requirement of SLM manufactured parts.

Abstract This paper attempts to improve the physical and mechanical properties of selective laser sintered polyamide PA2200 components through a vibratory surface finishing process by inducing severe plastic deformation at the outer surface layers. The industrial target of additive manufacturing components is to obtain structures having surface roughness, hardness, and other mechanical properties equivalent to or better than those produced conventionally. Compared to the as-built SLS PA2200 samples, vibratory surface finishing treated specimens exhibited a smooth surface microstructure and more favorable roughness, hardness, and tensile strength. Also, the duration of the vibratory surface finishing process showed a further improvement in the surface roughness and hardness of the SLS samples. Compared to the as-built state, the roughness and hardness of the surface-treated samples improved by almost 90% and 15%, respectively. Consequently, microstructural analysis indicates that lower surface roughness and enhanced surface hardness is a crucial factor in influencing the overall tensile strength of SLS-PA2200 components. We consider that the combination of VSF and SLS processes can successfully handle a wide range of potential applications. This study also highlights the efficiency and applicability of the vibratory surface finishing process to other additive manufacturing processes and materials. Graphic abstract

© 2019 Elsevier GmbHAdditive manufacturing (AM) has been becoming more widespread and its usage area has been increasing in various industries. However, the mechanical and microstructural properties of the metal parts fabricated by additive manufacturing requires further investigation. In this study, various heat treatment temperature were applied to Inconel 718 specimens fabricated by selective laser melting (SLM) to examine their effects on microstructure, microhardness and wear behavior of the specimens. Moreover, the microhardness and wear response of specimens fabricated by SLM were compared with the wrought Inconel 718. The results provide strong evidence that heat treatment temperature is capable of altering microstructural aspects of as-built specimens. This study also shows microhardness and wear resistance is remarkably induced from the final state of microstructure. Comparative study also provides evidence that Inconel 718 specimen fabricated by SLM can have much higher wear resistance than conventionally produced Inconel 718 if it is heat-treated at certain temperature.

This study focuses on optimizing cutting parameters of NiTiHf high-temperature shape memory alloys using a multi-objective optimization method. The empirical models are used to predict outputs in a turning process of Ni-rich NiTiHf and compared to experimental data. Cutting parameters, such as cutting speed, feed rate, and depth of cut, have found a great effect on performance criteria of turning processes in machining process of this alloy. These parameters were optimized by using Genetic Algorithm to obtain maximum tool life, minimum energy consumption, and maximum surface quality. TUBITAK (The scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [116M346]; NASA Aeronautics Research Mission Directorate (ARMD) Transformational Tools & Technologies (TTT) project Financial support from TUBITAK (The scientific and Technological Research Council of Turkey) under Project number 116M346 is greatly acknowledged. OB acknowledges support and funding from the NASA Aeronautics Research Mission Directorate (ARMD) Transformational Tools & Technologies (TTT) project. WOS:000653611400001

The topic of sustainable machining has in recent times emerged as a significant and impactful area of research focus as it directly deals with environmental health and protection, economic growth and prosperity, and societal wellbeing with greater health and wellness. More specifically, sustainable machining at product, process, and system levels deals with reducing negative environmental impact, offering improved energy and resource efficiency, generating a minimum quantity of wastes, providing operational safety, and offering improved personal health. This paper summarizes recent efforts by the world research community in sustainable machining with a systematic approach for the analysis of machining processes that are broadly classified as sustainable, beginning with dry machining, and then near-dry (also known as minimum quantity lubrication (MQL)) and cryogenic machining processes. The paper also extends its analysis to a hybrid mode of sustainable machining that effectively combines cryogenic and MQL machining processes for improved productivity and machining performance. While a significant part of this paper presents experimental analysis, the progress being made in modeling and optimization has also been discussed in the paper. In particular, major challenges involved in model development for practical implementation, with a view to selecting optimum cutting conditions and cutting tool selection, are primarily discussed in the paper. The need for continued modeling efforts for achieving deployable optimized conditions for sustainable machining is highly recognized, and further research is required in numerous fronts integrating the various convergent disciplines such as materials, mechanics, computational sciences, economics, environmental sciences.

A metal component fabricated by additive manufacturing (AM) is generally required to be heat treated to enhance microstructural and mechanical aspects. This present study aims to contribute to the literature in understanding the effect of heat treatment and various heat treatment temperatures on as-built components fabricated by AM. In this study, various heat treatment temperatures were applied to 316L stainless steel specimens produced by selective laser melting (SLM) and the effects on the microstructure, microhardness, XRD response, porosity, and wear behavior were investigated. The microhardness, XRD, and wear response of SLM 316L were compared with those of wrought 316L. The results illustrate that the heat treatment temperature has a substantial effect on the evolution of microstructure, XRD response, and porosity. Our results also support the argument that the effect of porosity on wear behavior is more dominant than the effect on microhardness. It should also be noted that the wrought 316L stainless steel specimen shows much better wear resistance than SLM 316L specimen.

This present study focuses on the surface integrity characteristics of the machined NiTiHf high temperature shape memory alloys. The NiTiHf specimens were machined under dry, minimum quantity lubrication (MQL) and cryogenic cooling at two different cutting speeds. Experimental data on microhardness, latent heat and phase transformation temperature is presented and analyzed to evaluate the surface and subsurface characteristics of the machined NiTiHf specimens. It is found that machining process particularly cryogenic machining alters microhardness, latent heat and phase transformation temperature of Ni-rich NiTiHf alloy. This study demonstrates that cryogenic machining process leads to occurring strain hardened layer on the surface and subsurface of machined workpiece. Phase transformation response including transformation temperature and latent heat for transformation of this affected layer shows significant difference comparing with the bulk of the workpiece. This difference is evidently observed from the cryogenically machined specimens than the specimens machined under dry and MQL conditions.

One of the challenges is to produce holes with expected dimensional accuracy in metal additive manufacturing. Although post-processing is usually carried out for the additively manufactured components but improving the quality of the holes produced through additive manufacturing seems to be requirement. Otherwise, it is difficult to obtain expected quality for the holes in metal components. Therefore, this study focuses on drilling operation of Inconel 718 alloy fabricated by selective laser melting additive manufacturing. Specimens fabricated by selective laser melting (SLM) were drilled using carbide drill bit under various drilling conditions including cutting speed and feed values. The measured outputs were surface quality of drilled hole, surface topography, surface and subsurface microhardness, and microstructure. Obtained results were compared with the results from wrought Inconel 718. This study showed that drilling process helps to improve the surface quality of additively manufactured Inconel 718 by reducing the surface roughness. Besides, increased feed rate results in work hardening effect on the hole surface and eventually microhardness of surface and subsurface increases notably.

Selective laser melting (SLM) is one of the most commonly used additive manufacturing (AM) techniques to manufacture metal components; however, during building process partially melted powders and/or pores on the outer surface of metallic parts results in very high surface roughness and eventually poor surface quality of components manufactured by selective laser melting. Thus, post-processing is needed to improve surface quality and also control subsurface characteristics. Hence, this study presents the effects of finish machining process on surface integrity characteristics including surface roughness, microhardness and XRD analysis of selective laser melted (SLMed) Inconel 718 alloy. In machining process of SLMed Inconel 718 alloy, the effect feed rate on measured outputs was also examined. Besides, the role of cold air on surface integrity characteristics was also presented in this study. This study reveals that arithmetic average surface roughness of as-built SLMed Inconel 718 can be lowered more than 90% with finish machining post processing operation. Increased feed rate results in work hardening on the surface and subsurface and eventually microhardness of surface and subsurface increases notably as compared to as-built SLMed Inconel. Finish machining process deeply influences XRD patterns of SLMed Inconel 718 alloy. (C) 2018 The Authors. Published by Elsevier Ltd.

This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish (A f) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.

It is a well-known fact that Titanium alloys are commonly used materials in various industries, in particular aerospace and biomedical applications. Among titanium alloys, Ti-5553 is a new generation high temperature near beta alloy. As it has superior properties such as high tensile strength and fatigue life, it has a potential to be used in aerospace industries for structural components to replace Ti-6Al-4V. This study provides investigation on the effect of material parameters including material model parameters and frictional conditions on simulating chip formation in orthogonal cutting process of this alloy. Experimental data are used to compare forces, contact length, and to predict chip form in the cutting process of Ti-5553 alloy. This study illustrates that with calibrated frictional condition and critical damage value, it is possible to predict forces, contact length and chip morphology that can show good agreement with experimental data. (C) 2017 The Authors. Published by Elsevier B.V.

Additive Manufacturing (AM) has been recognized as a promising manufacturing technology for the industries including aerospace and biomedical; however, the surface finish requirement for the components used in such industries imposes a severe constraint. Thus, finishing process for any manufacturing operation including additive manufacturing needs to be investigated to provide insights into the finish processing-surface property relationship. In this study, finishing operation in milling process is considered as a post-processing to improve the surface, mechanical and wear properties of the specimens fabricated by selective laser melting (SLM). This study demonstrates that surface and subsurface characteristic such as surface topography, surface roughness, microhardness, and wear resistance is substantially affected from milling parameters. Finish-milling operation with the high feed rate results in 50% reduction in wear rate of the specimen fabricated by SLM process.

New-generation aerospace alloys gain more interest due to their advanced properties. Ti-5553 alloy can be categorised as new-generation aerospace alloys, but it is also difficult-to-machine material. For this reason, machining performance and the role of cutting parameters on machining of this particular alloy needs to be well investigated. This study aims to contribute to understand machining performance of Ti-5553 under various cutting parameters including cutting speed, feed rate and depth of cut. Machining performance tests were carried out without using any cooling and lubricant. Tool wear, cutting forces, chip breakability and surface quality were considered as measured machining performance criteria. This study reveals that the depth of cut and cutting speed have a profound effect on the machining performance of this material by substantially affecting tool wear and cutting temperature and thus all measured machining performance outputs.

Titanium alloy Ti-5Al-5V-3Cr-0.5Fe (Ti-5553) is a new generation of near-beta titanium alloy that is commonly used in the aerospace industry. Machining is one of the manufacturing methods to produce parts that are made of this near-beta alloy. This study presents the machining performance of new generation near-beta alloys, namely, Ti-5553, by focusing on a high-speed cutting process under cryogenic cooling conditions and dry machining. The machining experiments were conducted under a wide range of cutting speeds, including high speeds that used liquid nitrogen (LN2) and carbon dioxide (CO2) as cryogenic coolants. The experimental data on the cutting temperature, tool wear, force components, chip breakability, dimensional accuracy, and surface integrity characteristics are presented and were analyzed to evaluate the machining process of this alloy and resulting surface characteristics. This study shows that cryogenic machining improved the machining performance of the Ti-5553 alloy by substantially reducing the tool wear, cutting temperature, and dimensional deviation of the machined parts. The cryogenic machining also produced shorter chips as compared to dry machining.

This work explores the machinability and sustainability of newly developed environment-friendly hybrid techniques for Ti-6Al-4V turning in terms of energy consumption, surface finish, and machining costs. Performances obtained under hybrid turning techniques namely cryogenic-ultrasonic assisted turning and cryogenic-ultrasonic-minimum quantity lubrication assisted turning are compared with the cryogenic assisted turning technique. Energy consumption in the turning processes is assessed in terms of energy consumed by the machine tool, active cutting energy, and energy efficiency. Results show that active energy consumed by machine tool is decreased by up to 1.8–3.6% using hybrid turning techniques as compared to cryogenic assisted turning technique. An increase in energy efficiency values is observed at higher levels of input process parameters using all three turning techniques. Average surface roughness values are decreased by up to 32%–42% using hybrid turning techniques as compared to the cryogenic assisted turning technique. A sustainability index, i.e., relative sustainability of process is used to quantify the sustainability of the turning operations. The results show a significant role of newly developed hybrid technologies in the machining industry to meet energy-saving and sustainability goals without compromising product quality.

This experimental study focuses on various cooling strategies and lubrication-assisted cooling strategies to improve machining performance in the turning process of AISI 4140 steel. Liquid nitrogen (LN2) and carbon dioxide (CO2) were used as cryogenic coolants, and their performances were compared with respect to progression of tool wear. Minimum quantity lubrication (MQL) was also used with carbon dioxide. Progression of wear, including flank and nose, are the main outputs examined during experimental study. This study illustrates that carbon dioxide-assisted cryogenic machining alone and with minimum quantity lubrication does not contribute to decreasing the progression of wear within selected cutting conditions. This study also showed that carbon dioxide-assisted cryogenic machining helps to increase chip breakability. Liquid nitrogen-assisted cryogenic machining results in a reduction of tool wear, including flank and nose wear, in the machining process of AISI 4140 steel material. It was also observed that in the machining process of this material at a cutting speed of 80 m/min, built-up edges occurred in both cryogenic cooling conditions. Additionally, chip flow damage occurs in particularly dry machining.

Ti-5553 alloy is considered as a next generation aerospace alloy, however, it is also considered as difficult-to-machine material due to its thermal and mechanical properties. As limited research work presented in literature on machining process of this alloy, more research is needed to determine appropriate machining strategies for this alloy. Thus, this study presents extensive experimental work to asses the machining performance of this next generation aerospace alloy in a wide range of cutting speeds by utilizing high pressure coolant (HPC) delivery, minimum quantity lubrication (MQL), and flood cooling. Machining performance measures are tool wear rate, force components, and chip breaking. Surface and subsurface characteristics of machined parts were evaluated focusing on surface topography, dimensional accuracy, microhardness and XRD analysis. The obtained results showed that high pressure coolant delivery remarkable improved machining performance of this alloy at higher cutting speeds as compared to flood cooling and MQL. Considering surface integrity characteristics, surface and subsurface hardness shows decreased trend in all conditions and cutting speeds as compared to hardness of as received material resulting from thermal softening. XRD analysis illustrated that alfa and beta peaks shows noticeable broadening and reduced intensity but no phase transformation is observed.

Sekil hafizali alasimlar (SHA), benzersiz ozelliklerinden dolayi biyomedikal alanda yaygin sekilde kullanilmaktadir. Bu alasimlar arasinda, NiTi alasimlari en cok kullanilan malzemelerdir. Bu alasimlari sekillendirmek icin kullanilan bir yontem de talasli imalat teknigidir. NiTi alasimlari mekanik olarak kesilmek zorunda kaliyorsa, kristal kafes yapisi degisebilir ve faz donusumu meydana gelebilir. Bu, dogal olarak kesme kuvvetlerini ve takim omrunu etkiler. Bu calismada, kritik talas kalinligi, NiTi alasiminin mikro kesme kosullari altinda frezelenmesiyle deneysel olarak belirlenmistir. Bunun icin, yuksek hassasiyette ve yuksek kesme hizlarinda kesme yapabilen bir deney duzenegi kullanilmistir. Calismada, genis bir aralikta dis basina dusen ilerleme degeri ve talas derinligi kullanilmistir. Calismada cikti parametreleri olarak kesme kuvvetleri, yuzey puruzlulugu ve capak olusumu goz onune alindi. Elde edilen sonuclar, NiTi SHA icin kritik talas kalinliginin 0,5mm oldugu tespit edilmistir. Kritik talas kalinligi, kesici kenar radusunun yaklasik %33 ne karsilik gelmektedir. Bununla birlikte, artan kesme hizina bagli olarak, hem kesme kuvvetleri hem de capak genislikleri artmaktadir.

Materials with ultrafine-grained (UFG) structure become the prioritised selections for specific applications where high strength, hardness, wear/corrosion resistance, etc. are sought. Machining mat...

There has been a substantial growth in using carbon fiber-reinforced plastic (CFRP) composite materials in aerospace and automotive industries due to their superior properties. This experimental study presents results from a comprehensive and systematic study investigating the effects of cryogenic cooling on drilling performance and surface integrity characteristics of CFRP composite material. Experimental data on cutting edge radius of drill bit, outer corner wear of drill bit, trust force, torque, delamination factor, and surface integrity characteristics, including borehole subsurface damage and diameter error of drilled hole, are presented and analyzed comparing dry drilling with cryogenic cooling of CFRP composite material. The findings demonstrate that cryogenic cooling has a profound effect on reducing the cutting edge rounding of drill bit and outer corner wear; it also helps enhancing the surface integrity characteristics of produced hole. However, cryogenic cooling generates larger thrust force, torque, and thus larger delamination factor.