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Compliant mechanisms are widely used for instrumentation and measuring devices for their precision and high bandwidth. In this paper, the mechatronic model of a compliant 3PRS parallel manipulator is developed, integrating the inverse and direct kinematics, the inverse dynamic problem of the manipulator and the dynamics of the actuators and the control. The kinematic problem is solved, assuming a pseudo-rigid model for the deflection in the compliant revolute and spherical joints. The inverse dynamic problem is solved, using the Principle of Energy Equivalence. The mechatronic model allows the prediction of the bandwidth of the manipulator motion in the 3 degrees of freedom for a given control and set of actuators, helping in the design of the optimum solution. A prototype is built and validated, comparing experimental signals with the ones from the model. Authors would like to thank the Ministerio de Ciencia e Innovación of the Spanish government for funding the project PID2019-105262RB-I00.

A common problem in motion control is the onset of vibrations due to the inertial forces when a compliant load is being displaced. It is the case of the vibration of large machine tools, but also the vibration of slender loads in pick&place. The main goal of the present work is to predict and minimise the overshoot that a compliant load moved by a servodrive suffers when it reaches the final position. Instead of modifying the control algorithm or adding dampers, the authors propose an optimal path planning based on the selection of a square sine velocity profile, a standard in machine tools NCs. Thus, a 3 degrees of freedom mechatronic model that integrates the dynamics of the drive-transmission-compliant load system and the control has been developed to predict the overshoot. Analysing the velocity profile, it has been possible to determine several values of the commanded jerk that minimize the overshoot and are related to the natural frequency of the compliant load. The prediction of the overshoot magnitude as well as the optimal jerk values have been experimentally validated in a workbench with a single axis with a ball screw transmission and a compliant load where a laser interferometer has been used to measure the overshoot.

Parallel continuum mechanisms are closed, kinematic, chained compliant mechanisms that are mobile due to flexible and slender elements. Large deformations and the force-moment equilibrium require a more complex modeling of the kinematic analysis than in their rigid-link counterparts. Although real-time solutions to the position problem using numerical iterative methods are available, a comprehensive kinematic analysis of such mechanisms has not yet been conducted. The first step to this end is a procedure that solves the full forward and inverse kinematic problems, and is proposed in this paper for planar systems to allow for an easier interpretation of their kinematic characteristics. This procedure provides the means to obtain multiple solutions arising from the closed-loop structure and the multiplicity of the buckling mode of slender links.

It is important for the mechatronic design of robotic systems to rely on accurate models. To that end, system identification methods are a convenient tool to obtain the values of the unknown dynamic parameters which play a key role. In this paper, it is investigated the application of the principle of energy equivalence to easily obtain a suitable model for identification of the inertial parameters and friction of planar mechanisms. The methodology here proposed is then applied to the prototype RePlaLink, a 5R haptic mechanism. Experimental data was obtained to carry out the identification, and the results were then validated by using a different trajectory than the one used for the identification of the unknown parameters. It was found that the identified model developed for the mechanism using the herein described methodology, was able to predict the dynamic behavior of the mechanism.

The development of large machinery in the industry of the machine tool implies moving heavy structural components and pieces. The consequence is the apparition of inaccuracies at the tool tip during the motion due to the high inertial forces acting on the compliant machine. To predict the dynamic behavior of these machines, a three degree of freedom mechatronic model has been developed considering the dynamics of the transmission chain of the drive, the machine structural element dynamics, and the control. The model can be used in the design stage to estimate the maximum jerk that can be commanded without the appearance of overshoot at the tool tip. Also, it can be used to predict the bandwidth of the whole mechatronic system. The model has been tested in a ball screw-based test bench with a compliant mass that simulates the structural compliance of a real large machine tool.

Current CAM and milling verification software packages are not ready to predict form and surface errors derived from non-ideal conditions such as runout tool error or tool–workpiece flexibility. As a consequence, high-end parts like integral blade rotors (IBR) suffer from this lack of estimation to achieve a sound manufacturing process preparation. This work describes the implementation of a cutting force prediction model that introduces the radial engagement reduction caused by (i) tool runout and (ii) workpiece flexibility. The model is used as the seed for a calculation module based on solid modeling to obtain the surface roughness and topography applying the cutting force–wall restitution equilibrium, making use of the power of CAM solid modelers for the final topography definition. This idea takes advantage of the good accuracy of current solid modelers in comparison with the z-map topographical approach for obtaining the cutter–workpiece engagement (CWE) at each tool path step. Several flank milling tests were carried out to validate the simulations. The results demonstrated a significant level of accuracy to predict shape errors. The model may be integrated in a CAM procedure, and it is a useful utility for reducing deformation on the manufacturing of blisks and impellers.

In this paper, the interaction between the dynamics of the routing process and the vibration behavior of the ARABA I lightweight machine is presented. Firstly, the dynamics of the routing is evaluated by the critical depth of cut of the lobes diagrams of the process. Secondly, the structural dynamics of the machine is analyzed by means of its experimentally validated finite element model. Considering the compliance of the machine as the only source of deformation, the interaction of the machine-process dynamics is evaluated and useful outputs are obtained. The critical depth of cut, the frequency of chatter, and the chatter-free workspace are depicted in the operational workspace of the machine. These results are finally used to propose some design and material improvements in the machine which lead to an enhanced performance in the routing process.

Productivity and surface finish are typical user manufacturer requirements that are restrained by chatter vibrations sooner or later in every machining operation. Thus, manufacturers are interested in knowing, before building the machine, the dynamic behaviour of each machine structure with respect to another. Stability lobe graphs are the most reliable approach to analyse the dynamic performance. During heavy rough turning operations a model containing (a) several modes, or (b) modes with non-conventional (Cartesian) orientations is necessary. This work proposes two methods which are combined with multimode analysis to predict chatter in big horizontal lathes. First, a traditional single frequency model (SFM) is used. Secondly, the modern collocation method based on the Chebyshev polynomials (CCM) is alternatively studied. The models can be used to identify the machine design features limiting lathe productivity, as well as the threshold values for choosing good cutting parameters. The results have been compared with experimental tests in a horizontal turning centre. Besides the model and approach, this work offers real worthy values for big lathes, difficult to be got from literature. Basque Country Government, GAITEK program.

The application of laser cladding technology is becoming widely extended in the industrial environment due to its advantages of high added value and direct manufacturing or repair of complex parts. These complex parts require 5-axis laser cladding deposition processes whose programming demands optimized and continuous tool paths. The present work develops a programming methodology for a homogeneous material deposition of a continuous 5-axis laser cladding process applied to rapid manufacturing of blisk blades. Initially, the blisk blade geometry is defined and the process requirements are studied considering key factors such as the best parameters, nozzle trajectories, and feed values. Therefore, the proposed algorithm solution for feed variation control is applied to the process obtaining a more homogeneous structure. Finally, a blisk case study is developed according to the proposed solutions.

The stability of a thin wall workpiece milling process is investigated through a single degree of freedom system that mimics the milling machine operation. The stability lobes were computed by using the Enhanced Multistage Homotopy Perturbation Method (EMHPM), the Chebyshev Collocation, the Semi-Discretization and Full-Discretization methods. A comparison of these methods with respect to experimental data and computational time was made to identify the method with the best performance in terms of accuracy and computational time in order to optimize the material removal rate by using the Simulated Annealing algorithm (SA). Then, we have used the EMHPM with the SA algorithm to establish the optimal cutting conditions. Based on numerical simulation computed by combining the SA algorithm with the EMHPM and experimental data, we have determined the optimum cutting condition in less than 400 ms which is 100 times faster than the off-line methods used to find the stability lobes.

Conference Paper presented at The Joint International Conference of the XII International Conference on Mechanisms and Mechanical Transmissions (MTM) and the XXIII International Conference on Robotics (Robotics ’16) In the field of parallel kinematics few designs use highly deformable elements to obtain the end effector movement. Most compliant mechanisms rely on notches or shape changes to simulate a standard kinematic joint. In this work a kinematic model of a simple parallel continuum mechanism that combines a deformable element and cable is presented. The kinematic model is used to study the workspace of the manipulator and is validated by experimental measurements of a prototype. The authors wish to acknowledge the financial support received from the Spanish Government through the Ministerio de Economía y Competitividad (Project DPI2015-64450-R) and the Regional Government of the Basque Country through the Departamento de Educación, Universidades e Investigación (Project IT445-10) and UPV/EHU under program UFI 11/29.

High performance position control in machine tools can only be achieved modelling the dynamic behavior of the mechatronic system composed by the motor, transmission and control during the design stage. In this work, a complex analytical model of a ball screw drive is presented and integrated in a mechatronic model of the actuator to predict the dynamic behaviour and analyze the impact of each component of the transmission. First, a simple 2 degrees of freedom model is presented, and is analysis sets the basis for the development of a more complex model of several degrees of freedom, whose resulting fundamental transfer functions are represented using natural and modal coordinates. The modeling in modal coordinates carries a reduction of the transfer function that reduces computational work. The two models are compared and experimentally validated in time and frequency domain by means of experimental tests carried out on a specifically developed ball screw drive test bench Ministerio de Economía y Competitividad: Project DPI2015-64450-R (MINECO/FEDER, UE) University of the Basque Country (UPV/EHU) under the program UFI 11/29 Departamento de Educación, Política Lingüística y Cultura” of the regional government of the Basque Country (IT949-16)

In this work, a methodology for the assessment of the geometrical accuracy of a multiaxis machine, the type usually called multitasking machine, was fully developed. For this purpose, the well-known formulation by Denavit and Hartenberg was applied. Multitasking machines are derived from lathes in which turrets are substituted by milling spindles, or they are also derived from milling centres including a turning headstock on the machine bed. In both cases, they are kinematically much more complex than lathes or milling centres, where it is not easy to previously calculate the consequence of parallelism and squareness errors between elements and joints. In this paper, a radical new ‘multitasking’ machine model was studied. Literature shows a complete lack of values for this kind of machine. In the methodology presented here, errors were introduced as additional geometric parameters in each elemental transformation matrices, resulting in the real transformation matrix for a multitasking machine. Elemental errors and the way to introduce them into the Denavit and Hartenberg matrices are fully described. Some simulations are tested, giving a useful outcome regarding the sensitivity of the machine with respect to the feasible assembly errors or errors produced by light misalignments caused by the machine tool continuous use.

Aeronautics is a business in a continuous growing sector and aircraft manufacturing is without any doubt a high-priced process. Each part of the aircraft and particularly engine parts represent the most expensive elements due to the difficulty of manufacturing their complex geometry. In this case, the test piece to carry out the study has been the Blisk. The predicted lead time for one of these components is so long that any progress related to the manufacturing process implies a considerable amount of saving. Due to the critical nature of the parts common defects such as chatter marks, smearings or pickups originated during the manufacturing process that will reduce the part life are not allowed. In this article, considering the existing demand of better manufacturing technologies a study case based on an Inconel 718 Blisk finishing operations study is developed. A static model for machining forces prediction is developed to finally validate it with the real machining forces measured during the machining process.

The objective of this work is to develop a manipulator of 5 degrees of freedom for micromilling. It consists of a XY stage under a 3PRS compliant parallel mechanism, obtaining the advantages of the compliant joints as are higher repetitiveness, smoother motion and a higher bandwidth, due to the high precision demanded from the process, under 0.1 μm. In this work, the dynamics of the compliant stage will be developed. The modelling approach is based on the use of the Principle of Energy Equivalence combined with the Boltzmann-Hamel equations to analyze the rotational dynamics of the platform. A pseudo-rigid model has been assumed for the compliant joints, calculating the flexural and torsional stiffness by FEA. Finally, a prototype has been built and some preliminary results are shown comparing the simulation and the measurements. The authors of this paper wish to acknowledge the financial support received from the Spanish Government via the Ministerio de Economía y Competitividad (Project DPI2015-64450-R), the ERDF of the European Union, the Government of the Basque Country (Project GIC07/78, IT445-10 and SAIOTEK 2013 SAI13/245, SPC13UN011), and the University of the Basque Country (Zabalduz-2012)

This paper deals with the static characterisation of a parallel manipulator for routing processes. Since accuracy and surface finishing are critical in all machining processes, the performance of a parallel machine is analysed in this paper in terms of these parameters. Using a previously developed static analysis methodology, the stiffness of the machine structure is obtained and used as an input for a process model. This approach allows the static behaviour of the machine to be evaluated in terms of the surface location error for a given routing operation in the manipulator workspace. The study focusses on certain discrete points in the operational workspace for each direction of the tool feed. Then, the global behaviour of the machine is presented using surface location maps. Furthermore, some static constraints are imposed to obtain the static workspace of the manipulator for the routing process.

This work deals with the characterization of a three stage multivariable tool used for high-performance milling and the modelling of its dynamic behaviour to predict the stability against chatter. The influence of the variable pitch, variable helix and variable rake angle on each cutting edge of the tool is modeled to calculate the stability lobes diagrams. The proposed approach includes a mechanistic milling forces model and a cutting coefficients characterization procedure along with a modification of the Enhanced Multistage Homotopy Perturbation Method (EMHPM) to capture the multivariable phenomena of the tool in stability prediction, resulting in an accurate method to reproduce the regenerative vibration problem in end milling. Experimental data is provided to validate the followed approach for this new tool concept.

Chatter vibrations produced during turning of slender parts or boring with flexible tools lead to a wavy work surface, and reduce the spindle headstock life span as well. This study deals with the problem of chatter prediction in straight turning of non-rigid parts, making use of round inserts. A stability model for straight turning has been developed using the Chebyshev collocation method for the first. This algorithm allows the introduction of an accurate round insert edge geometry, discretising the lead position angle and the variable cutting coefficients of the forces model along the edge. The method is applied to a SDOF system by means of a specially designed testpart and demonstrates its usefulness to determine chatter-free conditions.

Modern industry requires high-precision machines and processes. This requirement implies the determination and reduction of all possible sources of error. For turning, a main error is related to machine–tool–workpiece deformation caused by cutting force. On the other hand, current turning centers are structurally more complicated than conventional lathes. However, stiffness values for this kind of machine are not described yet in literature. Thus, the aim of this work is to provide stiffness values for this type of machines clamping a common workpiece. To obtain this information an experimental methodology to measure static stiffness along kinematic chain of the turning center is proposed. The method may be useful for both users and machine manufacturers in order to consider this factor in the general error budget of the turning process. At the same time, stiffness values for lathes with a Y-axis incorporated in a three-axis turret and equipped with living tools are registered.

Ever increasingly, universities have to face the demands of their students regarding tools and methods to complete their education in preparation for the industrial environment. On the other hand, the university has to meet a Research and Development function oriented to the improvement of the competitiveness of that environment. These are two different functions that the university must unite to offer an optimum service. Hence, the university needs tools that can meet this dual function: teaching and researching. This paper proposes the concept of a “Glass Machine” as a dual purpose approach based on the adaptation of machine tools to satisfy that dual function. This concept has been applied to a machine tool by means of two machines: a turn-milling centre and a feed-drive test bench, which have been used for practices in the subjects of 4th and 5th year of Industrial Engineering, allowing at the same time the usual research activity of the High Performance Machining Team. In short, this work is about the optimization of the available resources of the university, thus satisfying the needs of the students and the industrial environment.

This paper provides an integrated approach for designing large milling machines, taking both mass reduction of mobile structural components and the maximum material removal rate into account. This approach considers a representative milling operation and a productivity target as a starting point, and then deals with the design of the machine to achieve the targeted productivity with structural components of minimum mass. The procedure is based on modeling the interactions between process and machine by means of a stability model of the milling process in modal coordinates. The model allows the identification of the mechanical design parameters that limit the productivity as well as the threshold values that must be met to ensure the targeted productivity. Those values are reached in an iterative procedure that minimizes the mass of the critical structural components of the machine. This approach has been applied to the re-design of an actual milling machine, on which, once built and adjusted, the machining tests conducted have shown increases above 100% in productivity, consuming at the same time 13% less energy due to mass reduction above 20% in mobile structural components. In this way, an eco-efficient milling machine that performs highly productive machining processes has been designed and built.

High-speed machining has improved performance in manufacturing sectors such as the aeronautical, automotive, and mould and die industries. However, one problem of reaching such high speeds is the self-excitation of the spindle-tool system during the machining process. This so-called chatter vibration produces several negative effects: a reduction in surface quality and accuracy, and in tool and spindle life. Nowadays, it is still the most common limitation to increased productivity and quality of metal-removal operations. Although theoretically calculated stability-lobe diagrams can be used to calculate stable cutting conditions, some uncertainties affect the accuracy of this solution. This paper presents a method based on experimental tests where an inclined plane in the workpiece is machined at several spindle speeds. The gradual increase of the axial depth of cut allows the milling to be interrupted when chatter is detected. The final result is that the stability lobes are machined in the workpiece. This method can be used for process optimization and avoiding trial and error tests to determine optimal depths of cut and spindle speeds. The creation of a database with the optimal cutting conditions for a given spindle-tool holder-tool system can help the computer aided manufacturing (CAM) programmer select the cutting conditions that maximize the material removal rate and avoid vibration problems. The method presented is especially suitable for small- and medium-sized workshops where operators are unfamiliar with analytical methods or modelling techniques. It is an interesting way of saving money that does not require complex knowledge, and can easily be applied without additional costs owing to its simplicity.

Chatter is the most classical problem in machining. It is prone to occur in low rigidity structures generating poor surface quality and harmful vibrations which could damage any part of the machine-tool system. In finishing operations, the effect of the tool nose radius should be taken into account in order to obtain safe and reliable cutting conditions. The present paper uses a simple SDOF model to study the stability during finishing operations.

This article deals with the new development of a family of router milling tools for the high-performance milling of carbon fiber reinforced plastics. The new milling tools are shaped by multiple left-hand and right-hand helical edges, which form small pyramidal edges along the cutting length. Several substrates and coatings have been tested including AlTiN and the new naCO with nanocrystalline structure. After the analysis of tests and modifications on the tool prototypes, the final result is a series of routing endmills optimized for carbon fiber composites defining the influence of each of milling tool features on tool performance, which was not clearly established till date. The specific cutting forces, tool wear, and others aspects are discussed in detail.

This paper presents a model for the prediction of surface topography in peripheral milling operations taking into account that the tool vibrates during the cutting process. The model includes the effect of tool vibrations in the equations of the cutting edge paths, which are transformed into equivalent polynomial equations and solved for discrete positions along the feed direction by applying a standard root finder. Through this procedure, surface topography generation is simplified with respect to other models in literature. The model allows the topography, the roughness values and the form errors of the milled surface to be predicted. Cutting test results show good agreement with model predictions.

This paper presents a model for the topography prediction of ball-end milled surfaces, considering the tool parallel axis offset. First, the equations of cutting edge trajectories and the envelope equation of the material swept by the tool are derived. Later, the trajectories are cut by planes perpendicular to the feed direction obtaining a set of transcendental equations that are solved by transforming them to polynomial equations through Chebyshev expansions. This procedure presents the advantage on previous models in literature of not requiring any starting point to achieve the solution. Finally, experimental results are presented and compared to the model predictions.

In this paper, a procedure for the kinematic design of a 3-PRS compliant parallel manipulator of 3 degrees of freedom is proposed. First, under the assumption of small displacements, the solid body kinematics of the 3-PRS has been studied, performing a comprehensive analysis of the inverse and forward kinematic problem, and calculating the rotations that the revolute and spherical flexure joints must perform. Then, after defining some design requirements and therefore the necessary displacements to fulfill, a design process based on the finite element calculations has been stablished, giving the necessary guidelines to reach the optimal solution on a 3-PRS compliant mechanism. Also, a prototype has been tested, using a coordinate measuring machine to verify its dimensions and the resulting displacements in the end effector and the actuated joints. Finally, those measurements have been compared with the FEM and the rigid body kinematics predictions, contrasting the validity of those two modelling approaches for the kinematic design of compliant mechanisms. The authors of this paper wish to acknowledge the financial support received from the Spanish Government via the Ministerio de Educación y Ciencia (Project DPI2011-22955) and Ministerio de Economía y Competitividad (Project DPI2015-64450-R), the ERDF of the European Union, the Government of the Basque Country (Project GIC07/78, IT445-10 and SAIOTEK 2013 SAI13/245, SPC13UN011), and the University of the Basque Country (Project EHUA13/30 and Zabalduz-2012). Thanks are also addressed to Dr. Jorge Presa and Alfonso Urzainki from Egile Corporation XXI for their valuable contributions.

The structural properties of La 2 O 3 and Al 2 O 3 –La 2 O 3 binary oxides prepared by sol–gel were studied by XRD, HRTEM and UV–vis. The binary oxides with high lanthana contents show an amorphous structure after calcination at 650 °C. At calcination temperatures higher than 1000 °C there is a phase transformation from the amorphous state to the crystalline LaAlO 3 with a perovskite structure. The structure of La 2 O 3 is consistent with the hexagonal system; however, some crystalline microdomains with a monoclinic structure were detected by HRTEM. Islands of La 2 O 3 and LaAl 11 O 18 phases were detected at high lanthana concentration in the binary oxide. The modification in the coordination shell of the Al 3+ cations due to the interaction with La 3+ cations confirms the formation of phases with a perovskite structure and the presence of islands of the LaAl 11 O 18 phase.

In this paper, a 3D dynamic model for the prediction of the stability lobes of high speed milling is presented, considering the combined flexibility of both tool and workpiece. The main aim is to avoid chatter vibrations on the finish milling of aeronautical parts, which include thin walls and thin floors. In this way the use of complex fixtures is eliminated. Hence, an accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor.

High speed machining of low rigidity structures is a widely used process in the aeronautical industry. Along the machining of this type of structures, the so-called monolithic components, large quantities of material are removed using high removal rate conditions, with the risk of the instability of the process. Very thin walls will also be milled, with the possibility of lateral vibration of them in some cutting conditions and at some stages of machining. Chatter is an undesirable phenomenon in all machining processes, causing a reduction in productivity, low quality of the finished workpieces, and a reduction of the machine-spindle's working life. In this study, a method for obtaining the instability or stability lobes, applicable when both the machine structure and the machined workpiece have similar dynamic behaviours, is presented. Thus, a 3-dimensional lobe diagram has been developed based on the relative movement of both systems, to cover all the intermediate stages of the machining of the walls. This diagram is different and more exact than the one that arises out of the mere superposition of the machine and the workpiece lobe diagrams. A previous step of rejecting resonance modes that are not involved in the milling at the bottom zones of the thin walls must be previously performed. Finally, the proposed method has been validated, by machining a series of thin walls, applying cutting conditions contrasted with the limits previously obtained in the three-dimensional lobe diagram.

At present, airframes are mainly composed of monolithic components, instead of small parts joined using welding or riveting. Ribs, stringers, spars, and bulkheads can be included in this category. After milling, they are assembled and joined to the aircraft skins, which have also been milled. The aim of these parts is to obtain a good strength-weight ratio, owing to their homogeneity. The milling of a monolithic structural part implies removing up to 95 per cent of the weight from the raw block material. Therefore, the main objective is to achieve the highest removal rate possible. However, conditions required to achieve this (high feed, large depth of cut) in milling imply high cutting forces, which in turn induce part deflection or vibrations in those zones (thin walls and floors) where stiffness is not sufficiently high. These static and dynamic problems often lead to inaccuracy of geometry, roughness, and possible damage to the machine spindle. This paper proposes a working methodology for efficient process planning, based on previous analysis of the static and dynamic phenomena that can occur during high-speed cutting. This methodology provides several steps that can be taken in order to minimize the bending and vibration effects; suggests optimal monitoring methods to detect process instability; and describes the best way to tune the cutting conditions and chip load, by means of simulation at different machining stages. In this way, the reliability of aeronautical production significantly increases. The global approach presented in this paper has been applied to two test pieces and two real parts, which were milled without suffering either static or dynamic problems.

In this chapter the main methods, machining strategies and possible problems when flank milling complex surfaces, are deeply explained. Flank milling is an operation defined by using large axial depth of cut with end milling tools, high cutting speed and relatively small radial depths of cut. This process is especially recommended for ruled surfaces machining, whose tangential contact of the involving cylinder with the cutting tool body is the key factor to define the tool paths. Due to the complexity of these kinds of surfaces, 5-axis milling is required taking special care of the geometrical interferences between the tool and the complex geometry of the pieces in order to avoid collisions. Finally, a new model for the prediction of roughness and dimensional accuracy on thin-walled component is presented, along with examples of parts with surfaces which need the flank milling operations due to their complexity.

The milling of thin parts is a high added value operation where the machinist has to face the chatter problem. The study of the stability of these operations is a complex task due to the changing modal parameters as the part loses mass during the machining and the complex shape of the tools that are used. The present work proposes a methodology for chatter avoidance in the milling of flexible thin floors with a bull-nose end mill. First, a stability model for the milling of compliant systems in the tool axis direction with bull-nose end mills is presented. The contribution is the averaging method used to be able to use a linear model to predict the stability of the operation. Then, the procedure for the calculation of stability diagrams for the milling of thin floors is presented. The method is based on the estimation of the modal parameters of the part and the corresponding stability lobes during the machining. As in thin floor milling the depth of cut is already defined by the floor thickness previous to milling, the use of stability diagrams that relate the tool position along the tool-path with the spindle speed is proposed. Hence, the sequence of spindle speeds that the tool must have during the milling can be selected. Finally, this methodology has been validated by means of experimental tests. Gobierno Vasco, programa Etortek Manufacturing 00

This chapter deals with spindle technologies for machine tools. The machine tool spindle provides the relative motion between the cutting tool and the workpiece which is necessary to perform a material removal operation. In turning, it is the physical link between the machine tool structure and the workpiece, while in processes like milling, drilling or grinding, it links the structure and the cutting tool. Therefore, the characteristics of the spindle, such as power, speed, stiffness, bearings, drive methods or thermal properties, amongst others, have a huge impact on machine tool performance and the quality of the end product. Machining requirements differ greatly from one sector to another in terms of materials, cutting tools, processes and parameters. Nowadays, the spindle industry provides a large variety of configurations and options in order to meet the needs of different industries. Therefore, it is crucial that companies correctly identify their machining requirements and make well-informed decisions about which spindle to acquire. In this chapter, some of the main spindle characteristics that are the basis of a wellinformed decision regarding spindles are introduced and discussed.

This chapter is focused on analysing new concepts and trends related to the structure of machine tools. In fact, the structure of the machine has a decisive influence on the three main parameters that define the capabilities of a machine, which are: motion accuracy, the productivity of the machine and the quality of machining. In this respect, this study on structural components will add a new basic parameter, eco-efficiency, because the structure of the machine also has a decisive influence on the whole life cycle of the machine and especially on the materials and energy resources consumed: an issue of increasing concern among machine tool builders.

International audience; The milling of thin-walled parts can become a seriously complex problem because the parts have variable dynamics. Firstly, the dynamics evolution of the part has been calculated through Finite Element Method (FEM) analysis. Then, the 3D stability lobes have been calculated for the thin walls and the thin floor. Finally, several milling tests have been performed in order to validate the predictions made by the model.

In this work, the advantages and drawbacks of Ultrasonic Assisted Turning (UAT) have been investigated focusing on the effect of tool vibration on surface quality. Several experiments have been performed on mild steels changing the cutting speed, feed and depth of cut, to study how the influence of the ultrasonic vibration on the surface roughness varies depending on the cutting conditions. The results obtained show that the ultrasonic vibration can improve the surface quality. The authors also propose a new booster design based on the theory of longitudinal vibration of a bar with varying cross-sectional area for a higher amplification of the ultrasonic vibration.

The present work presents the results obtained when an ultrasonic vibration is applied to tool on the turning of mild steels. Currently high‐end materials, usually present low machinability so it is necessary to employ new machining technologies. Ultrasonic assisted turning (UAT) is presented as an effective process for machining these difficult‐to‐cut materials. In order to achieve a better understanding of the process, a complete study of the influence of the vibration parameters is presented when machining mild steels. Several parameter of UAT were monitored, including surface roughness, tool wear, chip formation by a high‐speed imaging camera, and tool temperature by means of an infrared camera: surface roughness and tool temperature decrease and an tool life increase as compared to conventional turning (CT).