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Additive Manufacturing (AM) technologies revolutionized the common understanding of manufacturing with their layer-by-layer building principle. However, the literature has documented their high energy requirements, which is not in-line with the current policies of energy and emission reduction. This ambivalence of AM opens the question for the research community about the wise choice of the manufacturing process to be adopted. This paper proposes a comparative LCA method to select the best manufacturing technology between Conventional Manufacturing (CM) and EBM plus Finish Machining (EBM+FM). The Life Cycle Assessment (LCA) is conducted under cradle-to-gate boundaries. Three metrics, namely the Cumulative Energy Demand (CED), cost and CO2 emissions are considered. Characterization of unit processes is done by using the recent findings in the literature which are included in the model for both process technologies. The Specific Energy Consumption (SEC) is connected to the Material Removal Rate (MRR) and to the average Deposition Rate (DRa), respectively for machining and EBM. The main finding of this research is the description of breakeven surfaces, which separate the regions of validity between machining and EBM, as function of the Solid-to-Cavity Ratio (SCR) and the DRa. Moreover, the presented methodology gives the possibility to compare the goodness of the different sets of design rules that can be chosen for EBM, thanks to the proper evaluation of the SEC parameter. Finally, a sensitivity analysis is conducted to assess the effect of the remaining key variables.

Wire Arc Additive Manufacturing (WAAM) is a fusion- and wire-based additive manufacturing technology which has gained industrial interest for the production of medium-to-large components with high material deposition rates. However, in-depth studies on performance indicators that incorporate economic and environmental sustainability still have to be carried out. The first aim of the paper has been to quantify the performance metrics of WAAM-based manufacturing approaches, while varying the size and the deposited material of the component. The second aim has been to propose a multi-criteria decision-analysis mapping to compare the combined impacts of products manufactured by means of the WAAM-based approach and machining.

In order to characterise the environmental performance of additive manufacturing (AM) processes, comparative analyses are required. Different manufacturing approaches (such as additive and subtractive ones), besides adopting different equipment, use different kinds and amounts of material. Therefore, the material-related flow has to be followed throughout the entire product life. Differences in environmental impact arise at each step of the life cycle: material production, manufacturing, use, disposal, and transportation. A life cycle-based methodology able to take due account of all the factors of influence on the total energy demand for the production of metal components is given in this paper. Decision support tools for identifying the most sustainable manufacturing route (subtractive versus AM-based approaches) are presented for different scenarios. The aim of the present paper is to contribute to the debate concerning the environmental impact characterisation of AM processes.

Summary The additive manufacturing of metal parts represents a promising process that could be used alongside traditional manufacturing methods. The research scenario in this field is still largely unexplored, as far as the technological solutions adopted to integrate different processes are concerned and in terms of environmental and economic impact assessment. In this article, an electron beam melting (EBM) process and a machining process have been analyzed and compared using a cradle-to-grave life cycle–based approach. The production of components made of the Ti-6Al-4V alloy has been assumed as a case study. The proposed methodology is able to account for all of the main factors of influence on energy demand and carbon dioxide emissions when the component shape is varied. The results prove that, besides the direct energy intensity of the manufacturing processes, the impacts related to material usage are usually dominant. Therefore, when complex geometries have to be manufactured, the additive manufacturing approach could be the best strategy, if it enables a larger amount of material savings than conventional machining. Vice versa, when a small amount of material has to be machined off, the high energy intensity of an EBM process has a negative effect on the performance of the process.

Additive Manufacturing has proved to be suitable for supporting or even replacing traditional manufacturing approaches in some industrial contexts. Among the various processes that can be used to produce metal parts, Wire Arc Additive Manufacturing (WAAM) is known to be an economically convenient, welding-based direct energy deposition technique for large parts with reduced complexity. The present paper proposes a structured modelling framework to assess whether WAAM could successfully substitute machining processes. The costs, manufacturing times, energy demand and carbon footprint are considered. A case study is presented to clarify and demonstrate the applicability of the proposed methodology.

The additive manufacturing of metal parts represents a promising process that could beused alongside traditional manufacturing methods. The research scenario in this field isstill largely unexplored, as far as the technological solutions adopted to integrate differentprocesses are concerned and in terms of environmental and economic impact assessment.In this article, an electron beam melting (EBM) process and a machining process have beenanalyzed and compared using a cradle-to-grave life cycle–based approach. The productionof components made of the Ti-6Al-4V alloy has been assumed as a case study. Theproposed methodology is able to account for all of the main factors of influence on energydemand and carbon dioxide emissions when the component shape is varied. The resultsprove that, besides the direct energy intensity of the manufacturing processes, the impactsrelated to material usage are usually dominant. Therefore, when complex geometries haveto be manufactured, the additive manufacturing approach could be the best strategy, if itenables a larger amount of material savings than conventional machining. Vice versa, whena small amount of material has to be machined off, the high energy intensity of an EBMprocess has a negative effect on the performance of the process

Additive Manufacturing is under the spotlight as potential disruptive technology, particularly for the production of complex-shaped structural metallic components. However, the actual AM process capabilities present some limitations in achieving the strict part quality requirements imposed by the aerospace and automotive sectors. Therefore, the integration of AM and conventional manufacturing represents an emerging scenario to be investigated. In this paper, a pure machining process and a hybrid production route (based on EBM and finish machining) are compared. The influence of material usage-related factors on costs and energy demand is discussed. The results prove that, despite precise process judgments are case-specific, the proposed methodologies are suitable to provide guidelines for identifying the optimal manufacturing route under multiple design objectives.

The material processing industry has to deal with material and energy reduction targets, and such a need becomes more and more urgent when future energy and resource consumption predictions are considered. The optimization of machining operations has conventionally been performed by identifying the range of process parameters that lead to the maximum efficiency, which are generally defined on the basis of maximum productivity and minimum cost criteria. Cost-based models are part of the industrial cultural background, while the emerging environmental impact analysis has not yet become fully established. The paper describes an approach that is aimed at the integration of system-level models for the environmental and economic assessment of machining. Process time, cost, energy demand and carbon dioxide emissions are assumed as optimization targets. The dry and wet turning of Ti-48Al-2Cr-2Nb and Ti-6Al-4V alloys, while varying the process parameters, is considered as a case study. The results highlight that the range of process parameters that allow the maximum process efficiency to be achieved is influenced by material machinability, and that a holistic approach to process optimization appears to be a key task which is worth further research efforts.

Nowadays manufacturing technologies have to be evaluated not only for the technical features they can provide to products, but also considering the environmental perspective as well. As long as the technological feasibility of a given process is guaranteed, processes minimizing resources and energy consumption have to be selected for manufacturing. With respect to this topic, the research studies in the domain of metal processing technologies predominantly focus on conventional material removal processes as milling and turning. Despite some exceptions, many other non-machining technologies, such as metal forming processes, are still not well documented in terms of their energy and resource efficiency, and related environmental impact. In this paper, an environmental challenge between two traditional technologies is developed: the environmental performances of a partial hot extrusion process and of a turning processes are quantified and compared. A Life Cycle Assessment (LCA) approach is implemented to properly analyze the considered processes. The material production step and the manufacturing phase to obtain a simple axy-symmetric aluminum component is considered for the Life Cycle Inventory (LCI) data collection step. Besides, the material and consumables usage and the consumed electrical power are measured in order to quantify the energy consumption of the manufacturing phase. Further, the environmental impacts related to the manufacturing of the extrusion dies and of the turning process are included in the analysis. The paper presents an early step of a wider research project aiming at identifying the greenest technologies as functions of given product features.

The industrial world is facing the challenge of reducing emissions by means of energy- and resource-efficient manufacturing strategies. In some cases, the exerted emissions and the energy demands related to conventional manufacturing processes are not as intensive as those required to extract and produce the raw materials of which the workpieces are made. Therefore, the consciousness of the impact of material usage and the eco-informed choice of the end-of-life scenarios are both needed in view of sustainable development. Aim of this paper is to offer a contribution to a better understanding of the environmental impact of forming and machining processes, for the production of Al-based components, when varying the aluminum recycling strategy.

Metallic material processing plays a significant role in terms of global environmental impact. As a result, energy- and resource-efficient strategies in the metal shaping technology domain need to be identified urgently. Recently, the scientific world has been paying more and more attention to the environmental impact analysis of manufacturing processes. Despite this increased attention, the state of the art in the domain of environmental impact analysis of metal shaping processes is still characterized by gaps in knowledge and in methodologies. In particular, metal forming processes are still not well documented, in terms of their environmental impact, and there is a lack of systematic and comparative approaches. This paper offers a contribution to a better understanding of the environmental impact of forming and machining processes. A thorough methodology has been developed to take into due account all the environmental factors of influence on both of the considered technologies. A comparative analysis has been performed, varying the production batch size and part geometry. The importance of an environmental performance analysis that can include both batch size and geometry variations is discussed and highlighted throughout the paper. Finally, the application of the proposed methodology has resulted in the setting up of an eco-design tool, here defined as a Process Sustainability Diagram (PSD), which allows the greenest technology to be selected for the analyzed case study, while varying the considered factors of influence.

Finite Element simulation of orthogonal cutting is nowadays assuming a large relevance; in fact a very large number of papers may be found out in technical literature on this topic. In recent years, numerical simulation was performed to investigate various phenomena such as chip segmentation, force prediction and tool wear. On the other hand, some drawbacks have to be highlighted; due to the geometrical and computational complexity of the updated-Lagrangian formulation mostly used in FE codes, a cutting time of only a few milliseconds can be effectively simulated. Therefore, steady-state thermal conditions are not reached and the simulation of the thermal phenomenon may be ineffective. In order to overcome such problem two different approaches are proposed in this paper. The former is based on a pure thermal simulation once the thermal flow on the tool is properly calculated. The latter, on the contrary, is based on an artificial modification of the heat transfer coefficient at the interface between the chip and the tool in the thermo-mechanical simulation. Both of the proposed methodologies are discussed in the paper, highlighting the advantages and the drawbacks of each of them.

Wear prediction in machining has been recently studied by FEM although the use of numerical methods for such applications is still a very challenging research issue. In fact, wear phenomenon involves many aspects related to process mechanics which require a very accurate modelling. In other words, only a very punctual code set-up can help the researchers in order to obtain consistent results in FE analysis. The high relative velocity between chip and tool requires effective material models as well as friction modelling at the interface. Moreover the prediction of temperature distribution is another critical task; in the paper some different procedures are discussed. Subsequently a wear model is presented and calibrated in order to obtain a suitable tool to be implemented in a FE code with the aim to describe the wear evolution during the simulation process. A proper designed experimental campaign supplied some reference data for model set-up and verify in the practical application. All these aspects are carefully discussed in the paper.

The reduction of CO2 emissions is an urgent objective to pursue. The scientific and the industrial world have gathered such challenge, starting to find out energy- and resource-efficient manufacturing strategies. From the literature review, in the domain of environmental impact analysis of manufacturing processes, two relevant knowledge gaps can be spotted: (1) the metal forming processes (and, in particular, the bulk forming processes) are still not well documented, and (2) there is a lack of systematic and comparative studies on energy and material flows enabling the identification of environmentally-friendly manufacturing design strategies. This research offers a contribution to a better understanding of the environmental impact of forming and machining processes. The performance of the two processes is evaluated and compared with the varying of the material usage related factors. The impacts on the final results of the aluminum recycling strategy as well as of the applied method to account for benefits of recycling are analyzed. Therefore, the paper represents an effort aimed at tuning and improving a methodology able to thoroughly analyze the environmental impact of a given process, and to better compare different manufacturing strategies from the environmental point of view.

The scientific studies in the domain of environmental sustainability of metal processing technologies predominantly focus on conventional material removal processes, as milling and turning. Despite some exceptions, many other non-machining technologies, such as metal forming processes, are still not well documented in terms of their energy and resource efficiency. Moreover, to properly evaluate the environmental impact of a given process, a standing-alone approach is no longer sufficient. In order to offer a valuable contribution in the domain of metal shaping sustainability, the present paper proposes a thorough methodology entailing to compare, from the environmental point of view, two traditional technologies: a hot extrusion process (mass conserving approach) and a turning (subtractive) one. A Life Cycle Assessment (LCA) based approach is implemented to properly analyze the considered processes. An axi-symmetric aluminum component was selected to develop the analysis on. Besides the analysis of material flows occurring all along the life cycle of the component, the material use and the consumed electrical energy necessary for the tools manufacturing are measured to properly quantify the environmental impact of the production phases. The most relevant influencing factors within each technology are identified and quantified. Moreover, an analysis of the environmental performance of the two processes at the varying of the batch size is presented. The paper aims at providing some general guidelines for the identification of the greenest technology as the main influencing factors change. © 2014 Elsevier Ltd. All rights reserved.

The surface characteristics of a machined product strongly influence its functional performance. During machining, the grain size of the surface is frequently modified, thus the properties of the machined surface are different to that of the original bulk material. These changes must be taken into account when modeling the surface integrity effects resulting from machining. In the present work, grain size changes induced during turning of AA7075-T651 (160 HV) alloy are modeled using the Finite Element (FE) method and a user subroutine is implemented in the FE code to describe the microstructural change and to simulate the dynamic recrystallization, with the consequent formation of new grains. In particular, a procedure utilizing the Zener–Hollomon and Hall–Petch equations is implemented in the user subroutine to predict the evolution of the material grain size and the surface hardness when varying the cutting speeds (180–720 m/min) and tool nose radii (0.4–1.2 mm). All simulations were performed for dry cutting conditions using uncoated carbide tools. The effectiveness of the proposed FE model was demonstrated through its capability to predict grain size evolution and hardness modification from the bulk material to machined surface. The model is validated by comparing the predicted results with those experimentally observed.

Gamma titanium aluminides are heat-resistant intermetallic alloys predestined to be employed in components suffering from high mechanical stresses and thermal loads. These materials are regarded as difficult to cut, so this makes process adaptation essential in order to obtain high-quality and defect-free surfaces suitable for aerospace and automotive parts. In this paper, an innovative approach for longitudinal external high-speed turning of a third-generation Ti-45Al-8Nb-0.2C-0.2B gamma titanium aluminide is presented. The experimental campaign has been executed with different process parameters, tool geometries and lubrication conditions. The results are discussed in terms of surface roughness/integrity, chip morphology, cutting forces and tool wear. Experimental evidence showed that, due to the high cutting speed, the high temperatures reached in the shear zone improve chip formation, so a crack-free surface can be obtained. Furthermore, the use of a cryogenic lubrication system has been identified in order to reduce the huge tool wear, which represents the main drawback when machining gamma titanium aluminides under the chosen process conditions.

Residual stresses play an important role in the service quality of a component. Therefore, it is essential to predict and control residual stresses on the machined surface and subsurface. The paper is focused on the numerical prediction of residual stresses in the orthogonal cutting process of a mild steel. An advanced approach to model heat transfer phenomena at the tool-chip interface was included in the numerical simulation. The FEM results were compared with some experimental data obtained turning AISI 1045 steel using uncoated WC tool.

Innovative nanostructured tool coatings were developed in order to machine titanium-based alloys. Two dedicated coatings, AlSiTiN and TiCN, were applied by PVD on WC-Co tool inserts, developing nanostructured layers exhibiting superior performances, laboratory tests results being confirmed by machining experiments. Coatings surface qualification included tribological evaluation by ball-on-disc set-up, ball-erosion test, nanoindentation, scratch test, surface texture analysis and SEM observation with EDS analysis. The results have been compared to machining performances in wet and MQL turning, showing a marked pattern of agreement among different indexes.

The attention to the environmental impact analysis of manufacturing processes has been increasing. Energy consumption is one of the main players for material removal processes. Models for estimating the specific energy consumption or for computing the total direct energy requirements have been developed over time. This paper proposes a comprehensive model for the system-level energetic analysis of machining processes, which includes all the activities related to workpiece material production, material removal, tool and cutting fluid production and usage. The application of the model to the turning of a Ti-6Al-4V alloy (under wet, MQL, and dry cutting conditions) is presented and discussed. The results allow identifying the optimum process parameters for energy consumption minimization.

The high-performance machining of difficult-to-cut alloys requires the development and optimization of high-performance tools, able to withstand the thermo-mechanical tool load without compromising the surface quality of produced components. In this context, the machinability of titanium aluminides still represents a demanding challenge. In this paper, the performance of cubic boron nitride (CBN) and polycrystalline diamond (PCD) cutting inserts is compared to that of uncoated and coated carbide tools. Longitudinal external turning tests were performed on a Ti-43.5Al-4Nb-1Mo-0.1B (TNM) at.% cast and hot isostatically pressed (HIPed) γ-TiAl alloy, by using a conventional lubrication supply. In addition, PCD tools were also applied under cryogenic cooling with liquid nitrogen. Results proved that PCD cutting tools have the potential to improve the machining productivity of titanium aluminides, due to their high hardness and excellent thermal conductivity. A noteworthy further increase of tool life was possible by using PCD cutting inserts under cryogenic cooling conditions.

The paper presents a study on the performances of innovative coatings for steel cutting tools in machining wood. A series of steel tools with different surface modifications, such as nitriding, application of antiwear DLC and CrN mono and multilayer coatings, has been applied to HSS18 and alloy steel 90CMV8 substrates. Tribological and erosion resistance of the samples was evaluated and related to the cutting performance, while surface analysis was carried out on the workmaterial at the end of the cutting tests. The overall tests indicated that the modified tools are promising in secondary transformation of wood. Furthermore, combined tribological and erosion studies allowed to individuate a wear mechanism and the possibility to foresee cutting performance in this application. © 2006 Elsevier B.V. All rights reserved.

This paper presents results from a comparative study of machining of Ti6Al4V alloy under dry, minimal quality lubrication, and cryogenic cooling conditions using coated tools at varying cutting speeds and feed rates. The influence of the cooling conditions on surface integrity and the product performance was studied in terms of surface roughness, metallurgical conditions, including microstructure, hardness, grain refinement, and phase transformation of the machined product. Results show that cooling conditions affect surface integrity of the product signifying the benefits of cryogenic cooling in improving the overall product performance. © 2013 Springer-Verlag London.

Wire electrical discharge machining (WEDM) is a manufacturing process suitable for high-precision cutting of complex and irregular shapes through difficult-to-machine electrically conductive components. In recent years, wire EDM has become a key non-traditional machining process, widely used in the aerospace and automotive industry. Although this technology has been broadly investigated, literature is still limited on the use of wire EDM for intermetallic alloys, and the applications on gamma titanium aluminides are rather unexplored. Such materials are attracting considerable interest due to the outstanding combination of properties, and they have proved to be eligible for thermo-mechanically stressed parts of aeroengines. Nevertheless, the poor machinability of gamma titanium aluminides has been reported in conventional (i.e. turning, milling, and drilling) and non-conventional machining, such as ECM. Further, machinability results strictly depend on the chemical composition of the specific alloy. This paper investigates the interactions between common process parameters of WEDM and final quality of the generated surface, through analysis of variance (ANOVA) and regression models based on experimental results. In particular, the paper is focused on the effects of pulse on time, pulse off time, servo-reference voltage, and wire tension on the surface finish during the WEDM of a Ti-48Al-2Cr-2Nb (at. %) γ-TiAl alloy. Results are discussed and compared with reference to the models available in literature.

When machining difficult-to-cut materials, the high temperature in the cutting area is one of the dominating phenomena affecting tool wear and process capability. Hence, cutting fluids are profusely used for cooling and lubrication purposes, in order to obtain satisfactorily process performances. The use of conventional fluids creates several problems, such as the environmental pollution due to chemical disassociation at high cutting temperatures, water pollution, soil contamination during disposal, and biological problems to operators. The implementation of green machining strategies to accomplish the increasing pressures for sustainability is therefore an open challenge for manufacturers and researchers. Aim of this paper is to evaluate the influence of the lubrication strategy on tool wear, surface quality and environmental impact when milling and turning Ti-48Al-2Cr-2Nb (at. %) intermetallic alloys. The workpieces were obtained by means of two production processes: vacuum arc remelting and electron beam melting (EBM). Coated carbide tools were used in cutting tests under different lubrication conditions. The results of dry cutting are compared to that of wet and minimum quantity lubrication (MQL) conditions. Overall, the experimental tests show that dry machining requires a sensible reduction of process parameters to preserve a stable process, although limiting the energy consumption and reducing to zero the lubricant consumption. Under the chosen cutting conditions, MQL appears to be an advantageous solution for milling, whilst in turning wet cutting is the best choice for reducing the tool wear, since the higher process temperatures require the higher cooling effect of the emulsion.

The present paper proposes a cutting tool breaking and chipping detection system for continuous and interrupted cutting, based on the analysis of the cutting force componentsFx andFy. A multifactorial experimental design has been carried out, to take account of the variability of the force signal. An adaptive signal processing algorithm is proposed, which detects catastrophic failure when at least one component deviates outside an estimated oscillation band for a time duration longer than a prefixed interval. The algorithm has been implemented on a four-microprocessor transputer board. Several tests confirmed the validity of the approach for detecting breaking and chipping phenomena in a few milliseconds, both in turning and in milling operations.

Gamma titanium aluminides are intermetallic structural alloys with many advantages like high temperature and oxidation resistance, low density, high specific strength, rigidity, etc. This makes them promising candidates for critical applications where both mechanical and thermal properties are required. Unfortunately, their machinability is demanding, generating low cutting life and poor surface conditions. A deeper knowledge on the machining parameters is essential for a wider application of these heat-resistant light-weight alloys in aircraft and automotive industry. In this paper, the performance of uncoated carbide drills in drilling a gamma titanium aluminide was analysed. The workpiece material was obtained via electron beam melting (EBM) process, a versatile technology for additive manufacturing of complex metal parts from metal powders. EBM is highly appealing in the field of aeroengine components, and it is particularly interesting in processing gamma titanium aluminides. Cutting performances were measured in terms of tool wear, surface roughness, dimensional and geometric errors. The experimental results show strong dependence of tool wear and part quality on cutting parameters, with poor tool life compared with other work materials.

Heat resistant gamma titanium aluminides are intermetallic alloys planned to be widely used in high-performance aircraft engines within the next few years. This application field is ascribed to the exceptional material properties, especially the low density and a unique strength-to-weight ratio for titanium-based alloys, good oxidation behaviour and thermal stability, limited ductility and fracture toughness below brittle-to-ductile transition, and good creep resistance. The demanding machinability of gamma titanium aluminides can be traced back to these desirable material properties. Consequently, cutting process adaptation is essential to obtain components suitable to satisfy strong regulations regarding surface integrity, without neglecting an economical production. Previous research activities confirmed that thermal material softening during cutting due to the high speed machining is a key to reach high quality surfaces, but tool wear was identified as the limiting factor. The relatively high cutting speed results in high temperatures in the shear zone and the low thermal conductivity of the γ -TiAl workpiece material leads to an extreme thermal tool load. Furthermore, in combination with the formation of saw-tooth chips and the discontinuous flow of the chip along the rake face, adhesive wear is caused. The influence of conventional flood cooling and high pressure lubricoolant supply (wet conditions), cryogenic cooling with liquid nitrogen, and minimum quantity lubrication (MQL) were investigated in longitudinal external turning operations. Tool wear, cutting forces, chip morphology and surface roughness were evaluated. Surface integrity was analysed in terms of machined surface defects and sub-surface alterations. The investigations indicate that cryogenic cooling is the most promising lubrication strategy, meaning that the thermodynamical impact of the expanding liquid nitrogen applied directly close to the cutting zone successfully counteract the huge thermal load on the tool cutting edges, providing potentially enormous benefits in terms of tool wear reduction and consequent surface quality improvement.

A fundamental wear cause in turning of austenitic steel with coated tools is the delamination of the coating around the cutting edge and the adjacent contact area. This is due to the strong adhesive effect between material and tool. The coating’s adhesion is influenced by several terms, e.g. coating process, substrate pre-treatment, coating system, substrate as well as by micro and macro geometry of the tool. This research work is focused on two fundamental aspects: the influence of the macro geometry on the delamination behaviour of the PVD-coating, and the possibility to use FEM simulation of chip formation as a useful tool for the interpretation of the coating’s failure. Several orthogonal cutting tests were performed under dry conditions, varying the rake angle between −15° and + 15°. Simultaneously, a FEM-model for the simulation of the thermal and mechanical loads of the tool was developed. The numerical model was verified by comparing simulation and experiments in terms of cutting forces and chip underside temperature. Experimental and numerical results show that high contact stress in the area of the rake face favours the partial removal of the coating by the sliding chip. According to this, large positive rake angles reduce the tendency towards coating delamination.

Innovative nanostructured tool coatings were developed in order to machine titanium-based alloys. Two dedicated coatings, AlSiTiN and TiCN, were applied by PVD on WC-Co tool inserts, developing nanostructured layers exhibiting superior performances, laboratory tests results being confirmed by machining experiments. Coatings surface qualification included tribological evaluation by ball-on-disc set-up, ball-erosion test, nanoindentation, scratch test, surface texture analysis and SEM observation with EDS analysis. The results have been compared to machining performances in wet and MQL turning, showing a marked pattern of agreement among different indexes.

Three innovative nanostructured coatings have been developed to be applied on cutting tools for continuous cutting of nickel-based super-alloys, in Minimum Quantity Lubrication (MQL) or dry conditions. The coatings, TiN+AlTiN, TiN+AlTiN+MoS2 and CrN+CrN:C+C, were applied by PVD techniques on WC-Co inserts, developing nanostructured layers, characterised by superior performances, as confirmed both by laboratory tests and machining experiments. Coatings surface qualification included SEM observations with EDS analysis, ball erosion test, nanoindentation and scratch tests, classic tribological evaluation by ball-on-disc set-up, surface texture analysis. Results were analysed in light of the outcome of machining experiments performed mainly in dry and MQL turning of Inconel 718. Ball-on-disc and scratch tests, as well as machining experiments, agreed in classifying the coatings in the following decreasing performance order: TiN+AlTiN+MoS2, followed by TiN+AlTiN, and by CrN+CrN:C+C.

The aim of this work is the development and characterisation of innovative ceramic coatings for cutting tools with high wear resistance properties at high temperatures. This objective arises from the industrial need of reducing machining time and consumption of lubricants, in order to reduce machining costs, environmental impact and health risks for the operators. The use of coatings for cutting tools is nowadays widespread, however, wear mechanisms are not always understood, and a clear relationship between coating's laboratory characterisation and operational machining performance are seldom assessed. The possibility of correlating the laboratory characterisation results with real tools operational performances would be a key issue in reducing development costs of innovative coatings. Nanocomposite coatings, consisting of nanocrystalline AlTiN dispersed in an amorphous matrix of Si3N4 were deposited onto hard metal substrates via Cathodic Arc PVD (physical vapour deposition). Coating's thickness, adhesion and hardness have been evaluated. Wear resistance was determined through tribological tests under different temperatures and the main wear phenomena were studied using SEM-EDS analysis. Coated WC cutting tools were employed in high speed, dry milling on AISI M2 die steel. Cutting performances, laboratory tests results and wear mechanism have been inspected, comparing with other commercial nitride-coated tools.

This paper reports a study on the most significant laboratory characterization tests for the performance assessment of innovative coatings for cutting tools, in order to obtain reliable forecasts over their machining behaviour. Ball-erosion tests, Rockwell C indentation, scratch test, ball-on-disc test at room temperature and at high-temperature, as well as nanoindentation and roughness measurements were applied to innovative nanocomposite coatings, and their results discussed and compared with the outcome of machining tests. The analysis of the results showed a good correlation between laboratory tests and cutting tests.

Nanostructured coatings were developed in order to machine nickel-based super-alloys in Minimum Quantity Lubrication (MQL), or dry conditions. Three dedicated coatings, TiN+AITiN, TiN+AITiN+MoS2 and CrN+CrN:C+C, applied by PVD on WC-Co inserts, developed nanostructured layers exhibiting superior performance, as confirmed by laboratory tests and machining experiments. Coatings surface qualification included, among other tests, SEM observation with EDS analysis, nanoindentation and scratch tests, classic tribological evaluation by ball-on-disk set-up, surface texture analysis. Dry and MQL turning experiments show substantial agreement with tribological and adhesion/toughness tests.

The hard abrasive ceramic component which increases the mechanical characteristics of metal matrix composites (MMC) causes quick wear and premature tool failure in the machining operations. The aim of the paper is to compare the behaviour of high rake angle carbide tools with their diamond coated versions in high-speed machining of an Al 2 O 3 Al 6061 MMC. The influence of the cutting parameters, in particular cutting feed and speed, on tool wear and surface finish has been investigated. The higher abrasion resistance of the coatings results in increased tool life performances and different chip formation mechanisms.