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This study reports on how ML algorithms are employed to investigate and predict surface roughness. Experiments were executed with a CNC milling machine, using AA7075 as part material and a "TiCN" coated tool. Feed rates per tooth, cutting speeds, cut depth, and cutting fluid were studied in response to roughness average (Ra) values. In the present study, Ra was measured with contact stylus tracing. Forty-two experiments were executed: thirty-three were used in all models training and nine in tests, and an additional experiment was carried out with diverse cutting parameters to validate the preferred models. This is the first study where thirteen ML algorithms, of which seven are basic and six are ensemble models, have been studied in the context of surface roughness. The study results showed that the voting regression model was the best model according to performance metrics (R2= 0.97, RAE = 0.17, RMSE = 0.0325, MAE = 0.13, and RSE = 0.09) and deviation 5.66%. Manufacturing companies can employ the voting regression model to predict surface roughness to enhance manufacturing efficiency, by harmonizing cutting conditions values against surface roughness. [ABSTRACT FROM AUTHOR]

V-free Ti-6Al-7Nb alloy may be an interesting candidate as a substitute to the traditional Ti-6Al-4V alloy on the development of biomedical components. The inspection of surface integrity through digital microscopy techniques shows strong potential for comparative analysis and optimization of manufacturing processes. This work deals with the comparative analysis of turned surfaces of dual-phase (α+β) titanium alloys: Ti-6Al-4V and Ti-6Al-7Nb, under different cutting conditions. Digital image processing and analysis technique has been used to evaluate the volume fraction of phases and their distribution. An innovative methodology for digitizing the surface topography was applied, based on the association of modern microscopy techniques with digital image processing-correlative microscopy. The global outcomes show that Ti-6Al-4V samples presented better homogeneity, with a mean β volume fraction of about 17%, compared to 11% of Ti-6Al-7Nb samples. The combination of higher feed rate and lower velocity produce rougher topography for both alloys, while the topographic formation obtained by the combination of lower feed rate and higher velocity seems smoother. In addition, Ti-6Al-4V alloy presents rougher topography in comparison topography of Ti-6Al-7Nb, under all conditions, probably due to the different phase distribution. The correlative microscopy allowed a correspondence between the cutting conditions and the microstructural properties of both Ti-6Al-4V and Ti-6Al-7Nb alloys, through the analysis of the machined surface. [ABSTRACT FROM AUTHOR]

In the present study, cutting conditions in face milling of AISI H13 hardened steel were optimized considering the performance of cemented carbide tool material. The initial microscopic mechanical property of the cemented carbide tool material was analyzed based on damage mechanics and boundary element method. Taking the initial microscopic mechanical property of the tool material, the initial macroscopic mechanical property of the tool material and external loads in the cutting process into account, a new tool life indicator was proposed. On the basis of the characteristics of tool life indicator and specific cutting energy, a theoretical method was established for the optimization of cutting conditions. The optimum cutting conditions were distinguished for different milling conditions. Feed per tooth fz with a value around 0.2 mm/tooth and cutting speed v ranging from 150 to 250 m/min should be used in symmetric milling to acquire a relatively long tool life and relatively low energy consumption. In down milling, feed per tooth fz should be in the range of 0.15 to 0.2 mm/tooth and cutting speed v should be between 100 and 200 m/min. Feed per tooth fz close to 0.2 mm/tooth and cutting speed v between 200 and 300 m/min should be adopted in up milling. [ABSTRACT FROM AUTHOR]

Hierarchical ribs can be used to keep balance between heat transfer enhancement and pressure drop reduction. The unique hierarchical structure which features a first-order asymmetric arc rib imposed by second-order microgrooves greatly reduces the pressure drop as well as enhances the heat transfer. However, it is hard for conventional machining techniques to generate such complicated configurations, especially freeform geometries in the micron range. Taking advantage of ultra-precision raster milling (UPRM), a novel one-step machining process, for advanced hierarchical ribs is proposed and demonstrated. In this paper, the principle of the cutting strategy for the second-order microstructures and cutting conditions that affect the basic features of the structures are discussed. In addition, three-level factorial design of cutting speeds, feed rates, and depth of cuts were set and used to machine hierarchical ribs on a copper workpiece. It was found that the cutting strategy was affecting the geometry of second-order microstructures of hierarchical ribs in UPRM. Moreover, the result revealed that at low levels of feed rate and cutting depth, a middle level of cutting speed provides a better quality of second-order microstructures than a middle level of feed rate, high level of cutting depth, and low level and high level of cutting speed. Maintaining a balance between machining efficiency and hierarchical structure generation quality is thoroughly assessed by machining second-order microgrooves on asymmetric arc primary surfaces. [ABSTRACT FROM AUTHOR]

In the aeronautical field, some parts are forged and consequently some fibers orientation occurs. However, the thin walls are hard to get with forging method. Consequently, some machining operations are done to get a thin wall and reduce the weight of part. However, because of the size of part of the volume of chips can be significant. The ratio between the final weight of part and the final weight of chips is approximately 80 %. To improve the economical and the environmental sustainability, a method consists of recycling directly the chip after machining operations. However, studies show a great impact of different points on chip recyclability like chip thickness, chip roughness, or chip density. Consequently, control of the chip morphology is a first point in ensuring a good recyclability. This article concerns the relationship between the cutting conditions, the cutting tool geometries, the lubricant conditions, and the chips morphology. This analysis is decomposed on several points: chip length, chip morphology, chip thickness, and the chip formation. The observations show also a strong influence of cutting conditions on chip morphology where an increase of cutting conditions reduces drastically the chip size. Concerning the chip formation, because the chip is produced during milling where the uncut chip thickness varies, the chip microstructure is then affected. [ABSTRACT FROM AUTHOR]

Over the past several years, titanium alloys have been increasingly used in aeronautics. However, they are considered to have poor machinability. The Ti-5553 near-beta titanium alloy is used in aeronautics to replace Ti-64 and for the production of structural parts, such as landing gears. Due to the low thermal properties and the high mechanical properties presented in this work, this alloy is considered difficult to machine. This work is devoted to understanding the relationship between the chip formation, the cutting process, and the tool wear. The first section studies the evolution of the tool wear. The tests show that tool wear occurs in three steps mainly due to the cutting process and the chip formation. To clarify these points, a section is dedicated to the chip formation and cutting processes. An analytical model is also used to quantify stresses, temperatures, and friction inside the workpiece material and at the tool/chip interface. Chip formation is commonly studied using a tool without wear, which can affect the cutting tool geometry. To verify chip formation and the cutting process during machining, a section describes the chip formation and the cutting processes using worn tools. [ABSTRACT FROM AUTHOR]

The Ti-1023 beta alloy titanium is used in aeronautics for the production of structure parts such as landing gear and as most of titanium alloys its machinability is poor explained by its physical and mechanical properties. This work presents the machinability results carried out for Ti-1023 milling in using toroidal tool. The aim of this research is the understanding of tool wear mechanisms and to establish the relation between cutting conditions, milling tool geometry, and tool life. A section is also devoted to the chip analysis. The wear modes are also analyzed and defined for different cutting tool geometries where several steps occur. This study is focus on material removal rate, tool life, and volume. [ABSTRACT FROM AUTHOR]

The wear on a tool cutting edge (called tool edge wear) develops rapidly in high-speed machining. Part I of the present study is a comparative study of high-speed machining of two widely-used aerospace materials (titanium alloy Ti–6Al–4V and nickel-based superalloy Inconel 718), focusing on a comparison between the effects of dynamic tool edge wear on cutting forces. This paper describes in detail the experimental setup as well as the measurements of tool edge wear and the cutting forces. A total of 60 high-speed machining experiments, which covered a range of cutting speed and feed rate conditions, were performed. The experimental results show that under the same cutting conditions, tool edge wear develops more rapidly in high-speed machining of Ti–6Al–4V than in high-speed machining of Inconel 718. Under the cutting conditions employed in the present study, tool edge wear does not significantly increase the cutting force but has a profound and complex effect on the feed force. The cutting force is higher in machining Inconel 718 than in machining Ti–6Al–4V. The feed force in machining Inconel 718 can be higher or lower than in machining Ti–6Al–4V, depending on the extent of tool edge wear and the particular cutting conditions employed. The analysis of variance (ANOVA) reveals that the extent to which the cutting speed and the feed rate affect the cutting forces in high-speed machining are highly dependent on the work material being machined. [ABSTRACT FROM AUTHOR]

Part II of the present study is a comparative study of high-speed machining of Ti-6Al-4V and Inconel 718, focusing on a comparison between the effects of dynamic tool edge wear on cutting vibrations. This paper describes in detail how cutting vibrations were measured and how vibration signals were processed using a wavelet packet transform technique. A total of 60 high-speed machining experiments were performed, covering a range of cutting speed and feed rate conditions. The experimental results show that tool edge wear has a complex effect on the cutting vibrations. The vibration amplitudes in high-speed machining of Ti-6Al-4V can be higher or lower than those in high-speed machining of Inconel 718, depending on the particular cutting speed and feed rate employed. Analysis of variance reveals that both the cutting speed and the feed rate always play a statistically significant role in affecting the vibration amplitudes in all three directions, i.e., the cutting speed direction, the feed rate direction, and the depth of cut direction. It is also revealed that in high-speed machining of Ti-6Al-4V, four significant wavelet packets (W30, W32, W33, and W36) exist, depending on the particular cutting conditions employed. In high-speed machining of Inconel 718, two significant wavelet packets (W32 and W33) exist, regardless of the cutting conditions employed. The significant wavelet packets identified in part II of the present study can be used as features to detect and monitor tool edge wear in high-speed machining. [ABSTRACT FROM AUTHOR]

Pocket milling is the most known machining operation in the domains of aerospace, die, and mold manufacturing. In the present work, GA-OptMill, a genetic algorithm (GA)-based optimization system for the minimization of pocket milling time, is developed. A wide range of cutting conditions, spindle speed, feed rate, and axial and radial depth of cut, are processed and optimized while respecting the important constraints during high-speed milling. Operational constraints of the machine tool system, such as spindle speed and feed limits, available spindle power and torque, acceptable limits of bending stress and deflection of the cutting tool, and clamping load limits of the workpiece system, are respected. Chatter vibration limits due to the dynamic interaction between cutting tool and workpiece are also embedded in the developed GA-OptMill system. Enhanced capabilities of the system in terms of encoded GA design variables and operators, targeted cutting conditions, and constraints are demonstrated for different pocket sizes. The automatically identified optimal cutting conditions are also verified experimentally. The developed optimization system is very appealing for industrial implementation to automate the selection of optimal cutting conditions to achieve high productivity. [ABSTRACT FROM AUTHOR]

Due to technical and economical factors, hard turning is competing successfully with the grinding process in the industries. Many practical applications require components to be hardened in order to improve their wear behavior. Higher productivity and good surface quality are the requirements of the modern industries. However, tool wear is the major problem in hard turning. The tool wear models, used to assess the performance of hard turning process, play an important role in predicting the surface quality. So, in the present work, an attempt has been made to develop an analytical tool wear model for the mixed ceramic inserts during the hard turning of bearing steel incorporating abrasion, adhesion, and diffusion wear mechanisms. The new model developed can reliably be used to assess the wear of the mixed ceramic tools within the domain of the parameters. It has been observed that tool wear is increasing with the increase in cutting speed, feed, and effective rake angle. However, it has been found to be slightly decreasing with the increase in nose radius. The proposed model was validated by conducting experiments. It could be seen that the model was capable of predicting the flank wear using the cutting parameters and tool geometry. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate the “manufacturability” levels for several machining processes of “slot” feature. Using the STEP standard, we identify the slot feature characteristics and then, using the ascendant generation of process method, we define the associated milling process. The expertise is based on a methodology relative to the experience plans carried out during the formalization and systematic evaluation of the machining process associated with the feature. [ABSTRACT FROM AUTHOR]

1. The modification of recommended cutting conditions obtained from a machining data handbook. 2. The incremental learning of obtained cutting conditions using fuzzy ARTMAP neural networks. 3. The substitution of better cutting conditions for those learned previously by a proposed replacement algorithm. Various simulations illustrate the performance of GELCC, and then the simulation results for a given part are provided and discussed. [ABSTRACT FROM AUTHOR]

This paper deals with a new method for determining cutting conditions for the machining of 3D sculptured surface shapes with a ball endmill. Since the interaction area between workpiece and cutting tool changes during ball endmill machining, the cutting conditions have to be changed accordingly. To determine the spindle speed, the tool-workpiece contact area is obtained from the depth of cut, path interval, and cutter contact (CC) data. The spindle speed is determined so that the tangential cutting speed of the centroid of the tool-workpiece contact area becomes the value suggested in the machining data handbook. The feedrate is determined so that the material removal rate is maximised within the range of the cutting-force constraint. The practical feasibility of the proposed scheme has been verified through experiments performed on a workpiece with sculptured surfaces. The test result shows that the new method can be used to increase the tool life, and improve the production rate. [ABSTRACT FROM AUTHOR]

This paper reports on the development of a module to calculate automatically tool paths and cutting conditions for metal cutting operations. Process planning must select correct cutting conditions to minimise disturbances on the shop floor owing to tooling problems. Tool path and cutting condition algorithms to generate reliable NC programs have been designed. The algorithms have been implemented in the framework of a generative computer-aided process planning system, called PART. Geometrical requirements to avoid chipping of cutting teeth are considered in tool-path calculation. The cutting conditions are calculated using metal cutting process models. A method has been developed to calculate cutting forces for milling operations based on experimental data of cutting forces in turning. In the process models, various constraints of the machine tool, cutting tool, and the workpiece are considered. [ABSTRACT FROM AUTHOR]