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Active magnetic bearing (AMB) is a substitute of conventional bearing, which provides electromagnetic force to support the rotating part respecting the stator. The utilization of electromagnetic force makes this bearing “active”. The attraction force of an AMB system can be control by manipulating the input so that the rotor can be levitate at required position. As lot of limitation exist in passive magnetic bearing, the AMB is very useful in modern applications. Due to frictionless nature of magnetic bearing and non-necessity of lubricants, now-a-days AMB is taking place as the alternate of any other bearing in multiple applications of growing industry. Adequate knowledge of essential components is necessary for successful implementation of any active magnetic bearing design. So, In this paper, the magnetic analysis has been analyzed for the different types of single and multi-axis AMB using ANSYS Maxwell with extensively reviewed components.

Maintaining minimal levels of geometric error in the finished workpiece is of increasing importance in the modern production environment; there is considerable research on the identification, verification and calibration of machine tool kinematic error, and the development of Postprocessor implementations to generate NC-code optimised for machining accuracy. The choice of multi-axis positioning function at the controller, however, is an often-overlooked potential source of kinematic error which can be responsible for costly mistakes in the production environment. This paper presents an investigation into how mis-management of the positional error parameters that define the rotary-axes’ pivot point can lead to unintended variations in multi-axis positioning. Four approaches for kinematic positioning on a Fanuc-based controller are considered, which reference two separate parameter locations to define the pivot point – managing the kinematics within the Postprocessor itself, full five-axis positioning with a fixture offset, full five-axis with rotation tool centre point control and 3+2-axis with a tilted workplane. Error vectors across four sets of rotary-axis indexations are simulated based on the theoretical kinematic model, to highlight the expected differences in geometric error attributable to mismatched pivot point parameters. Finally, the simulation results are verified experimentally, demonstrating the importance of maintaining a consistent approach in both programming and operation environments.

Multi-axis fused deposition modelling (FDM) 3D printing technology has been paid attention to by more and more people. However, existing FDM extruders are usually short and fat, which significantly restricts the popularization of multi-axis FDM 3D printing technology because one significant trend of additive manufacturing is the use of long and thin extruders to avoid collisions between extruders and workpieces in the printing process. This paper presents the design of a throat-extended FDM extruder to print complex-shaped workpieces with details. The main contributions in this paper include: (i) presenting a novel extruder structure including an extended-throat, a smaller heater block, and a cooling mini-fan; (ii) designing an optimized heater block using the shapes of its components and the milling tool as constraints to make its volume as little small as possible; (iii) Construct experimental and simulation methods to examine the temperature distribution of the throat to optimize the shapes of the heat dams of nozzle throats and the wind speed of the heat-dissipation fan. Based on the throat-extended FDM extruder, a five-axis FDM 3D printer has been developed, and various complex-shaped workpieces have been printed without any support.

Hollow blades, which are important components of aeroengines, have thin-walled structures and are subjected to vibrations in the machining process owing to its low rigidity and damping. This paper proposes an approach to enhance the machining stability of titanium hollow blades by introducing multiple damping and rigid supporters to the blade machining system in multi-axis milling process. A theoretical prediction model, considering the influence of original system, transmission and supporter, is established to predict the dynamic parameters of blade with a single damping or rigid supporter. Then, the model is applied in multi-supporter system and an optimization algorithm is used to determine reasonable positions of multiple supporters. The stability lobe diagrams of blade system with no supporter, optimized damping supporters and optimized rigid supporters are analysed and validated by blade machining experiment. The conclusion can be achieved that the sound signal is suppressed up to 40 % by adding optimized supporters and the machining stability is enhanced effectively.

Purpose This study aims to investigate the relationship between part porosity and mechanical properties of short-fibre reinforced polylactic acid printed via multi-axis material extrusion (MAMEX) to establish guidelines for optimal process configurations. Design/methodology/approach Material properties graphs provide the basis for studying the relationship between porosity and mechanical behaviour. Using the correlations found in this study, the way to improve printing strategies and filament properties can be deducted directly from an analysis of the print path and the final influence on mechanical performance. Findings Some commercial brands of short-fibre reinforced filament present inherent porosity that weakens the mechanical behaviour of MAMEX components. Originality/value Low-cost MAMEX allows the production of components that do not present anisotropic behaviour and are mechanically optimised through the alignment of the filaments along with internal stresses. This paper also addresses the effects of multi-axis deposition strategies on the resulting porosity and proposes improvements to reduce residual porosity, thus increasing the mechanical performance in the future.

This paper deals with a method to optimize tool axis orientations in multi-axis milling toolpaths. The method is based on calculation of the actual cutting diameter and the cutting speed during the toolpath. Subsequently, the NC code is processed by the interpolator with a machine tool kinematic model. The result is a visualization of the actual cutting speed and the real feed-rate on the toolpath. Based on these results, the vectors used to orient the tool axis along the toolpath can be effectively set up in several iterations. The toolpath are optimized to achieve a more constant cutting speedwhich lead to an improvement in surface quality and increase in productivity.

Using objective vibration evaluation to produce results highly consistent with real road ride comfort is challenging. The deficiencies in traditional evaluation indices, adopting an average operator, maximum operator, or cumulative operator as the main vibration information integration logic, are reported here through 19 designed road field tests in which major vibration information distribution covers all axes and vibration information is distributed in spacetime in various patterns. A new evaluation index which adopted a combination of maximum and cumulative operator is proposed to overcome these deficiencies and an interactive mechanism which standardized the process of selecting vibration information distributed among axes and spacetime is devised between the localized major vibrations. The results show that the proposed road ride comfort evaluation index is more consistent and accurate than the evaluation indices proposed by ISO 2631-1 and can be used more generally.

This paper presents a novel method to identify the squareness errors of computer numerical control (CNC) machine tools based on double ball bar (DBB) measurements. A series of spherical S-shaped paths are proposed to measure the squareness errors, instead of the generally used circular detection paths since the presented method requires only one experimental setup, and three translation axes are linked, which is more convenient and comprehensive. In this article, the coordinate transformation method and the method for dividing experimental paths evenly are used to solve the asynchronization between actual motion and DBB sampling process. The experimental data is then combined with the product of exponential (POE) model to calculate the three CNC machine tool squareness errors and applied to a spherical spiral testing path with the compensation of the diagnosed errors. The effectiveness of the method is verified by comparing the experimental results before and after the compensation.

Brass materials are widely used in many fields of machinery, especially plumbing applications. Parts produced from brass are processed in lathes or milling machines during the manufacturing phase. In this study, 6-corner pieces were produced by machining the MS58 brass alloy on the C-axis lathe with an end mill. As machining parameters, tool diameter, feedrate and rotation speed were selected. The effects of these parameters on average surface roughness (Ra), cutting time (t) and dimensional deviation (dev) were determined by the surface response method. Regression equations were created separately for surface roughness, cutting time and dimensional deviation. Later, parameter levels that optimize all three dependent variables together were obtained by grey relationship analysis. It was determined that the most effective parameter on surface roughness and dimensional deviation is the tool diameter. The most effective parameter on cutting time was found to be feedrate. The best combination of machining parameters was 10 mm tool diameter, 150 mm/min feedrate and 1000 rev/min rotation speed. The selection of parameters depends on the requirements based on better surface roughness, minimum cutting time, minimum dimensional deviation. Parameter levels that optimize surface roughness only are 10 mm tool diameter, 50 mm/min feedrate and 1000 rev/min rotation speed. Parameter levels that optimize cutting time only are 8 mm tool diameter, 143 mm/min feedrate and 1525 rev/min rotation speed. Parameter levels that optimize cutting time only: 10.31 mm tool diameter, 50 mm/min feedrate and 1000 rev/min rotation speed.

The high surface quality of free-form machined products is demanded by the industries. There were several different approaches proposed in the literature for improving the roughness/texture of machined surface, from tool path generation, tool orientation identification, tool geometry selection, to tool assembly error investigation on the causes and solutions. However, the traces caused by the asynchronous behavior of multi-axis tools were not widely discussed. This study explores the telltale surface characteristic left behind by a ball-end milling operation, using from the image process of scallops/cusps figure of the workpieces, through the spectrum/FFT (fast Fourier transform) plot to identify the parallel of the tool path and the types of traces. Using the distribution of peak frequency and related bandwidth as an index for the performance of synchronous machining, it will reveal the parameters setting of different motion control and the compliance of the dynamic synchronous motion. The tendency of performance index matched the measured roughness result of the workpieces.

In this paper, an optimized error sensitivity analysis (ESA) approach based on stream-of-variation (SOV) theory in multi-axis precise motion platform (MPMP) is introduced. Unlike the conventional ESA method, this approach utilizes stream-of-variation theory to establish error model firstly. By regarding each axis as a station, the error propagation and deviation accumulation processes are clear station by station. Through obtaining the deviations after each station, the sensitive stations can be developed, and corresponding error terms are collected. Thus, by analyzing the appearance frequency of the errors, a precise sensitive order can be developed, and a sensitivity results with different steps is given. Through ignoring the insensitive and irrelevant errors, the computational volume of error model can be saved, and the efficiency can be improved. A case study about a typical MPMP used in laser welding system (LWS) is carried out, and the results indicate that the optimized ESA approach is more efficient and accurate, and it is flexible as well. This ESA approach is not only accurate in developing sensitive levels, but also balancing the systematic accuracy and working efficiency, which is helpful to provide informative guide to engineers.

Tool path planning is critical to fully realise the producing capabilities of multi-axis machine tools and improve the precision and efficiency in multi-axis machining. Up to now, more than 400 art...

Vibration assisted machining (VAM) is a method that is widely used in improving the performance of machined products. External vibrations with high frequency to ultrasonic range along with an meso-micrometer amplitude are given to the cutting tool or workpiece. This will result in a periodic separation phenomenon, hence reducing the cutting force which has positive impacts on increasing tool life and machined surface quality. Among the high-precision machining processes, micro-milling which has the ability to produce complex components with 2D and 3D features, can also be applied with the vibration assisted method, known as vibration assisted micro-milling (VAMM). Based on the direction of vibration given in the machining process, there are 1D VAMM with linear vibrations and 2D VAMM with circular or elliptical trajectory vibrations. However to date, neither developed 1D nor 2D VAMM systems are still limited to the research of planar surfaces cutting using linear movement axes, meanwhile vibration assisted in inclination cutting of micro-milling using the rotational movement axes is still very rare. Therefore the purpose of this paper is to present the preliminary model in designing a 2D VAMM system for a 5-axis micro-milling machine. The system is powered using piezoelectric actuators as the vibration-producing actuators.

This research discusses the development and validation of a sustainable process chain for the efficient manufacturing of prototype gears for automotive applications. To reach the objectives, a selective laser hardening set-up has been integrated into a multi-axis machining platform. This allows to machine and harden gears in a single production center. In this research, 3 automotive drivetrain gears, representing a set of geometrical features (gear flanks,…) and materials, were manufactured and validated. Using the integrated laser hardening set-up, uniform hardness profiles were achieved on the different features while all measured quality parameters were within required tolerances.

The multi-axis force–torque sensor is a key element of many accurate force and motion control systems, including intelligent robotic systems. This paper presents a novel elastic structure for multi-axis force–torque sensors that is easily manufacturable at low cost and has many detection points with high surface strains. By using the “design of experiment” method in the ANSYS software, we demonstrate that the designed elastic structure with four identical T-shapes has high surface strains and can provide various strain gauge configurations. The strain sensitivities of the elastic structure at predetermined points can be maximized manually by varying the thickness of the vertical and horizontal beams of the T-shaped components. The validity of the proposed elastic structure is demonstrated through the development of a low-cost six-axis force–torque sensor. Experimental results for the developed force–torque sensor with the proposed elastic structure demonstrate that the proposed structure is comparable to an expensive state-of-the-art commercial force–torque sensor.

The article deals with the description of the production of a shaped part composed of an outer pyramid and cylindrical surface, of inner cylindrical surfaces of different diameters and of an inner tongue groove. It describes the proposed tools and tool holders resulting from the technological process. In order to meet the required tolerances and shape deviations for the given component, the CTX alpha 500 two-spindle multi-axis CNC lathe was chosen for its production. Its control system enables the workshop method of programming and simulation of individual operations in automatic mode or in block-by-block mode. The design of the selected CNC lathe enables the machining of rotary parts in one clamping, which is ensured by the right and left spindle with chucks. The surface quality of the pyramidal surface and the internal diameter of D18H8 was measured using a Hommel Etamic W5 roughness gauge. The measured roughness values for the hole were: D = 18H8, Rz = 3.007 μm, Ra = 0.729 μm and for the pyramidal surface: Rz = 1.527 μm and Ra = 0.329 μm.

In recent decades additive manufacturing has transformed from a set of prototyping meth- ods to a mature set of industrial level manufacturing processes. To achieve predictable and high-quality end-use products, these processes require the application of high-quality process planning solutions. This research questions the common perception that the nature of additive manufacturing processes has led to making process planning for additive manufacturing a trivial step. It is shown that duplicating process planning strategies from subtractive process planning algo- rithms leads to suboptimal results for their additive counterparts. The main focus of the re- search is thus the development of multi-axis process planning strategies that take the specific requirements of direct material deposition techniques (FDM, DED) into account. The research presented in this thesis starts with the state of art on multi-axis additive man- ufacturing. CNC based subtractive manufacturing strategies and established subtractive process planning steps and terminology are used as a starting point to address the specific challenge of process planning for additive manufacturing. The next chapters describe the development of two novel algorithms for multi-axis additive manufacturing path planning. The first algorithm is based on geometry decomposition that partitions the main geometry into sections with similar functional requirements. Within a partition, material is deposited using constant printing settings, while between the partitions the main deposition direction is optimized. The second algorithm is focused on calculating continuous multi-axis tool paths following the part surface geometry, thus preserving smooth motion of nozzle orientation and collision freeness of the additive manufacturing process. Simulations and physical ex- periments have been executed to validate the strategies proposed. The developed algorithm for multi-axis additive manufacturing reduced the surface roughness due to stair-case effect by 57% compared to 2.5D AM for the test part used.

The present study introduces a novel tool orientation angle optimization method for improving the machining accuracy of robotic milling systems. The proposed approach considers the intrinsic properties of serial mechanisms and their relationship with robotic stiffness to select optimal robot postures in the generation of tool orientation angle for finish cut. The evaluation of the robotic stiffness is carried out with two performance indices presented in this study: the volumetric stiffness performance index, which measures the overall robot stiffness, and the unidirectional stiffness performance index, which measures the robotic stiffness along a specific direction. As machining errors are reduced by optimally selecting the tool orientation angle without modifications to the tool path itself, the proposed method is significantly less convoluted than conventional optimization methods. The efficacy of the proposed method is validated experimentally using a purpose-designed multi-axis milling robot. Experimental results show that the robotic milling system is capable of machining three-dimensional shapes with a fine surface, and reducing the twist caused by the displacement of the cutting tool towards the direction of lowest robotic stiffness.

Aiming at the space cutter compensation problem for multi-axis machining of complex surfaces, firstly, a space cutter compensation method for multi-axis machining based on triple NURBS (non-uniform rational B-splines) trajectory is proposed, which can describe the machining trajectory information more completely and accurately, and is also expected to achieve dynamic radius and length compensation of multi-axis machine’s space cutter. Secondly, for the generation of NURBS trajectory of cutter axis vector and cutting contact vector, three error sources in NURBS curve offset process are analyzed in detail. The error scaling problem is especially pointed out, and a NURBS curve fast offset method with user-definable tolerance is proposed. Finally, the specific calculation method and system implementation scheme of space cutter radius and length compensation using triple NURBS curve trajectory are given. The effectiveness of the proposed space cutter compensation method was verified by simulation and machining experiments.

Multi-axis milling (especially five-axis) is in the ascendant for high precision manufacturing of a product with a sculptured surface such as ship propeller, owing to its multi-axis linkage and resulting outstanding superiorities. Needs of a faster-improving manufacturing level of sculptured surface milling are derived by higher performance requirement of complicated equipment, which makes the planning of tool orientations more significant and challenging. This paper builds a tool orientation optimization model with inclusion of the influence of deflection error caused by cutting force to achieve better machining precision controlling in five-axis sculptured surface milling. The basic idea of the optimization method is described firstly, followed by the prediction of cutter deflection error. Then determining processes of the related subset to restrain the tool orientations are developed. Lastly, comparative experiments are designed and performed through milling a propeller rotor possessing numerous blades in a five-axis machining center. By comparison with several other tool orientation methods, the average values and volatility of deflection error are both suppressed better utilizing the optimization modeling. The experiment results reflect that it is insufficient to consider single geometric constraint or kinematic constraint, and greater attention should be paid to the role of cutter deflection caused by cutting force in planning the tool orientations.

In situ scanning electron microscope (SEM) investigation is carried out on high-entropy alloy (HEA) specimen with various geometries to realize the multi-axial stress states. The dimple structure on the fracture surface is quantified and the nucleation of void is examined. The deformation twins can provide more sites for void nucleation and constrain shape change of the voids. Even under the low stress-triaxiality, the void can coalesce to reach large size accompanying twinning. The evolution of void size and density deduced from the fractograph is important to quantify ductile fracture of HEA.

This paper deals with global methods for experimentally determining the static stiffness of multi-axis machining centres. Different devices used for measuring deflection, in specific, are explored, where accuracy and usability are highlighted. The methods were tested on a 3-axis CNC milling machine, 2-axis trunnion table and a 6-DOF industrial robot.

The short article reviews the state-of-the-art of multi-axis toolpath planning, especially for polymer extrusion. The existing approaches for geometry-based and performance-based toolpath planning are emphasized and highlighted. The future perspectives of continuous fiber-reinforced composites are addressed to overcome the research gaps as well as improve the performance of products induced by polymer extrusion.

The article discusses the main methods of manufacturing products by layer-by-layer polymer fusion using non-planar layers. Conclusions are drawn about the disadvantages of these approaches. A proprietary method of manufacturing products on a multi-axis FFF 3D printer is proposed.

The high-precision measurement of blade profile has always affected the development of domestic aeroengine manufacturing industry. However, the traditional measurements have gradually failed to meet the increasing requirements of blade manufacturing accuracy. Aiming at the problem of detecting the aeroengine blade profile, the AGILITY multi-axis compound measuring machine is used in this paper. A measurement combining contact and noncontact is proposed, the practical test technology of blade is studied. Finally, the feasibility of the method is verified by analyzing the results. A technical scheme for the detection of blade profile of domestic aeroengine is provided.

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Reduction of contour error is crucial for multi-axis computer numerical control (CNC) machining to produce products with required geometric and dimensional accuracy. Although various contour error pre-compensation methods have been developed, few studies are dedicated to five-axis machines when compared with three-axis ones. In this paper, a new contour error pre-compensation method that integrates analytical prediction of contour error, optimal path-reshaping model, and decoupling solution algorithm is proposed for five-axis machining. First, by analyzing the dynamic responses of servo drive to the typical step and ramp signals, linear expression of servo tracking error with respect to the sequence of discrete axis positions is yielded for the prediction of contour error ahead of servo loops. Then, using the Taylor-series expansion and the pseudo-inverse matrix of the Jacobian function, a least-square optimization-based path-reshaping model that implies the satisfaction condition of zero contour error is analytically built. Thus, the complicated nonlinear contour error pre-compensation problem is converted into a simple quadratic programming problem. Concerning the effects of tool orientation reshaping on tool-tip contouring accuracy, a simple yet effective synchronous compensation strategy is subsequently proposed, through which both tool tip and tool orientation contour errors are reduced to near-zero without any iteration. To address the neighbor-dependence of the contour error compensation in adjacent cutter locations, a progressive solution algorithm with linear computational complexity is also briefly presented. Both numerical simulations and laboratorial experiments are conducted to validate the effectiveness of the proposed method.

Open blisks are important parts of aero-engines and plunging is a common and efficient method of rough machining open blisks. However, the research on the simulation of open blisk’s four-axis plunging is far from mature. In this paper, an in-process model of four-axis plunging is established to represent the part’s geometry in the process of plunging. Then, a method of evaluating the residual and overcut of the material is proposed. The minimum required bottom edge length is calculated based on the in-process model, and an algorithm to determine the critical plunging depth is invented. The simulation reveals that the method proposed is valid and can be used directly in industry.

Geometric errors measurement and identification for rotary table are important. However, precisely adjustment for the setup position of a double ball bar in each measurement pattern is inconvenient. This study proposes a novel optimization identification method using a double ball bar to recognize the position-dependent geometric errors (PDGEs) of rotary axis. A mathematical model for ball bar measurement is firstly constructed to map the relationship between measurement direction and position of the double ball bar. And then, the setup positions of the double ball bar for PDGEs identification are analyzed. According to analysis for setup positions of the double ball bar, simplified measurement patterns would be conducted by adjusting only two setup positions for the ball bar and thus reduce the procedure of accurate adjustment for the ball bar. The PDGEs can be fitted as an nth B-spline curve, on the account of its being smooth and continuous. To identify the PDGEs, an optimization method, by computing the suitable value of control points of nth B-spline curve of errors to minimize the optimal value of the target function between the actual measured value and the value derived from a theoretical measurement model, is proposed. Moreover, in order to obtain the accurate value of control points of the error curve, the sensitivity analysis is conducted to acquire the sensitivity matrix with respect to control points of errors. The PDGEs are able to be identified simultaneously after calculating the appropriate values of control points of errors. The proposed identification method is validated by simulation and experiment. The results prove the effectiveness of the proposed method.

In multi-axis machining of thin-walled workpieces such as a blade, especially at the semi-finishing and finishing stage, the depth-of-cut is in general selected very conservatively in order to alleviate the deflection of the workpiece during the machining. Moreover, for both semi-finishing and finishing, the depth-of-cut is usually set to be a constant. Aiming at achieving higher machining efficiency while maintaining a good finish surface quality, in this paper we present a new multi-axis machining strategy for thin-walled workpieces based on the idea of variable depth-of-cut machining. The proposed machining strategy strives to maximize the depth-of-cut locally for every cutter-contact (CC) point while respecting a threshold of the cutting force that is normal to the workpiece surface as it is the major effective force causing the deflection. The threshold of the normal cutting force varies depending on the position of the CC point on the workpiece and it is calibrated through physical experiments. A variable offset distance function is defined by setting the offset at each CC point equal to the maximum depth-of-cut at the point and based on which a multi-pass semi-finishing tool path is generated by offsetting the finishing tool path with the computed variable offset distance. Both computer simulation and physical cutting experiments are performed and their results show that a substantial reduction in both total machining time and machined surface error can be achieved by the proposed machining strategy for thin-walled workpieces.

In this study, high-molecular-weight-polyethylene sheets were welded in the butt-joint configuration in order to investigate the effect of welding parameters on the generated forces during welding. The welding procedure was performed using newly developed clamping device with the ability to measure and acquire the forces during welding in X, Y and Z directions (FX, FY and FZ). Using a welding tool with a stationary shoulder and position control, the applied force is kept approximately constant during the entire welding extension. The obtained results enabled the identification of the influence of each individual welding parameter on the applied forces. The axial force is the most influential force during this process, which is responsible for forging pressure and frictional heat, while traverse and rotational speeds have the main effect on the traversing and lateral forces. The developed sensitized clamping system was used in support of welding process optimization to produce quality welds without resourcing to costly force control sensors. Using this device, it was possible to use force as a welding parameter and produce strong welds with mechanical behavior close to the parent materials’.

Purpose This study aims to introduce a new method for locating candidate substrates in part models and evaluating their feasibility. Design/methodology/approach Slices of an STL model along candidate directions are evaluated for the fitting of regular cylindrical and rectangular stock. Next, the part model is skeletonized and tested for collision assuming deposition growth of features from the candidate substrate. Findings The method is successfully able to find feasible substrates and conduct collision simulation for a variety of part models. Research limitations/implications The algorithm is limited to cylindrical and rectangular substrates and only considers collision between the substrate and the deposition head. Originality/value This method represents a new approach to solving a portion of the hybrid manufacturing process planning problem.

This article proposes a method to analyze and compensate geometric errors of six-axis CNC grinding machines for spiral bevel gears. Volumetric error prediction and compensation models are realized by the forward and inverse kinematics modeling via the screw theory. Key geometric error items of motion axes and their influences on gear tooth performance are modeled and analyzed. Advantages of the proposed compensation method for geometric errors over the machine settings modification method are demonstrated. The compensation strategy has been verified on a six-axis grinding machine controlled by a Siemens CNC. The pitch error and tooth form error of machined gears before and after compensation are compared to validate the effectivity of the proposed compensation method.

In the current practice of multi-axis machining of freeform surfaces, the interface surface between the roughing and finishing process is simply an offset surface of the nominal surface. While there have already been attempts at minimizing the machining time by considering the kinematic capacities of the machine tool and/or the physical constraints such as the cutting force, they all target independently at either the finishing or the roughing process alone and are based on the simple premise of an offset interface surface. Conceivably, since the total machining time should count that of both roughing and finishing process and both of them crucially depend on the interface surface, it is natural to ask if, under the same kinematic capacities and the same physical constraints, there is a nontrivial interface surface whose corresponding total machining time will be the minimum among all the possible (infinite) choices of interface surfaces, and this is the motivation behind the work of this paper. Specifically, with respect to the specific type of iso-planar milling for both roughing and finishing, we present a practical algorithm for determining such an optimal interface surface for an arbitrary freeform surface. While the algorithm is proposed for iso-planar milling, it can be easily adapted to other types of milling strategy such as contour milling. Both computer simulation and physical cutting experiments of the proposed method have convincingly demonstrated its advantages over the traditional simple offset method. Keywords: Feed rate, Finishing and roughing process, Interface surface, Iso-planar tool path, Physical constraints

With the rapid development of aerospace, energy, and power technologies, the demand for high-performance parts with complex curved surface is increasingly large, and the multi-axis Computer-Numerical-Control (CNC) precision machining technique for such parts becomes a popular and difficult issue in the industrial field. In order to ensure the high-performance of complex curved surface parts, the requirement of the contour accuracy is higher and higher for such parts due to the important role they play in these fields. However, the limitation of dynamic properties for the CNC machine tools, which leads to the contouring-error, becomes a vital issue that affects the machining accuracy of the high-performance parts with complex curved surface. The contouring-error, defined as the orthotropic distance from the actual motion position of machine tool to the desired contour of curved surface in multi-axis contour-following tasks, is caused by the facts such as servo lag, dynamics mismatch, external disturbances, and so forth. The reduction of the contouring-error becomes of great significance for promoting the performance of CNC motion systems thus realizing the high-speed and high-precision machining, and the research on the contouring-error reduction in multi-axis CNC machining is therefore a hotspot issue in the machining engineering. This paper provides a comprehensive review to the state of the art of the contouring-error reduction methods. The massive and complicated studies on constraining the contouring-errors are classified and summarized, and accordingly, the advantages and the disadvantages of different kinds of methods are discussed and compared, which has a guiding significance for selection of the interested contouring-error reduction method. Furthermore, this paper systematically suggests the probable future studies that remain vacant and meaningful based on the discussion of the state of the art. Significantly, it is possible for active promoting and developing to further improve the contouring-error reduction of the complex curved surface parts in multi-axis CNC machining.

The improvement of the accuracy grade of main components in the production process through balancing between function and cost helps to improve the overall accuracy of machine tools. Therefore, this paper presents an improved value analysis method and uses the method of global sensitivity analysis and geometric error correlation analysis to analyze and optimize the error parameters of a 4-axis machining tool based on the proposed method. The geometric error modeling of the 4-axis machine tool was established by using the homogeneous transformation matrices (HTMs). By using global sensitivity analysis, the degree of influence of each error parameter on the accuracy of machine tool was obtained, and functional coefficient and cost coefficient of value analysis were gained by correlation analysis. An optimization model for geometric error budget of machine tool was established according to the improved value analysis theory, and the machining accuracy of machine tool was optimized according to the improved value analysis method.

This paper proposes an integrated geometric error prediction and compensation method to eliminate the positioning inaccuracy of tool ball for a double ball bar (DBB) caused by the translational axes’ geometric errors in a multi-axis machine tool (MAMT). Firstly, based on homogeneous transform matrix (HTM) and multi-body system (MBS) theory, the positioning error model only considering the translational axes of a MAMT is established. Then, an integrated error parameter identification method (IEPIM) by using a laser interferometer is proposed. Meanwhile, the identification discrete results of geometric error parameters for the translational axes are obtained by identification experiments. According to the discrete values, the optimal polynomials of 18 position-dependent geometric errors (PDGEs) are founded. As a basis, an iterative compensation method is constructed to modify the NC codes generated with the ordinary compensation method in self-developed compensation software. Finally, simulation verification is conducted with these two compensation methods. Simulation results show the positioning errors for test path of tool ball calculated with the iterative compensation method that are limited within 0.001 mm, and its average accuracy and accuracy stability are improved by 79.5 and 52.2%, respectively. In order to further verify the feasibility of the presented method, a measuring experiment is carried out in XY plane of a five-axis machine tool by using DBB. The experiment results show that the maximum circularity error with the iterative compensation method is reduced about 40.4% than that with the ordinary compensation method. It is therefore reasonable to conclude that the proposed method in this paper can avoid the influence of the translational axes’ geometric errors on rotary ones during a DBB test.

Process planning for hybrid manufacturing, where additive operations can be interlaced with machining operations, is in its infancy. New plastic- and metal-based hybrid manufacturing systems are being developed that integrate both additive manufacturing (AM) and subtractive (machining) operations. This introduces new process planning challenges. The focus of this research is to explore process planning solution approaches when using a hybrid manufacturing approach. Concepts such as localized AM build ups, adding stock to a CAD model or section for subsequent removal, and machining an AM stock model are investigated and illustrated using virtual simulations. A case study using a hybrid laser cladding process is used to demonstrate the opportunities associated with a hybrid solution. However, unlike machining, the process characteristics from system to system vary greatly. These are portrayed via a high power, high material deposition feed rate laser cladding system. There are unique challenges associated with AM processes and hybrid manufacturing. New tools and design rules need to be developed for this manufacturing solution to reach its potential.

Multi axis CNC machine tool has good linkage processing effect. Through the application of integral impeller in CNC machine tools, to improve the adaptability of CNC machine tools to complex surface processing parts, to improve the accuracy of multi axis CNC machine tools. The first part of this paper introduces the integral impeller and its machining characteristics; the second part introduces the basic NC machining process of integral impeller; the third part discusses the application of impeller in multi axis CNC machine tools from the creation of guide track, the simulation of integral impeller, software processing and generation. The purpose is to provide some reference for the processing and production of integral impeller.

Accuracy identification of geometric errors of rotary axis is important for error compensation of the multi-axis machine tool. However, it is not easy because of the influence of setup error of measurement instrument, and there exists angular errors and displacement errors need to be identified simultaneously. In this paper, a decoupled method based on double ball bar is proposed to identify the geometric errors of rotary axis including both position independent geometric error (PIGE) and position dependent geometric error (PDGE). A formulation for ball bar measurement is derived from kinematic analysis to reveal the relationship between sensitivity direction and setup position of ball bar. The angular errors and displacement errors can be identified separately when choosing the appropriate setup position and direction of ball bar. It can effectively reduce the interaction influence between them and improve the accuracy. To identify the 4 PIGEs, a method by averaging the measured results of ball bar to compute the eccentricity and slant of rotary axis is proposed. And, the PDGEs are leaved to mainly describe the oscillation of geometric errors of rotary axis. It is useful to correct the deviation error resulting from setup error of ball bar. For the identification of 6 PDGEs, by means of adjusting setup position and direction of ball bar, they can be identified one by one along the sensitivity direction of ball bar. Furthermore, in order to reduce the influence of setup error of ball bar, the sensitivity analysis is performed to obtain the sensitivity of measured results of ball bar with respect to setup error. According to the sensitivity characteristics of setup error, a method is presented to correct the PDGEs. Finally, several numerical simulations and experiments are conducted to verify the theoretical model and the proposed identification method. The results from the simulations and experiments demonstrate that the method can identify the geometric errors of rotary axis effectively and accurately.

The ISO accuracy test standard for five-axis machining centers was revised recently. A cone frustum cutting test by end milling, well-known for testing multi-axis controlled machine tools for aircraft part processing, is adopted in the ISO standard as a similar and precise test. It considers both the accuracy of the finished test piece and an interpolation accuracy test measured by ball bar in the same-feed motion of cone frustum cutting. Although it is possible to apply the ISO test methods to various structures of five-axis machining centers, the application of the cone frustum test to multi-axis machine tools with a rotary axis on the workpiece side is rare; thus, it is difficult to evaluate the test results. In this report, the ISO test method was outlined. Next, the ball bar cone frustum test was performed on a five-axis machining center whose two rotary axes were located on the workpiece side. The evaluation method of the test results is discussed. Moreover, the ball bar cone frustum test was also performed on turn-mill complete machining centers to confirm the effectiveness.

Additive Manufacturing (AM) technologies require innovative design paradigms and guidelines that exhaust the offered freedoms in geometry and material. The aim of the Design for Additive Manufacturing is to provide design opportunities and to enhance workpiece properties taking into account constraints of the process, e.g. kinematics and limitations of print technology. Most AM applications are constrained to three-axis movements limiting the fabrication of workpieces layer by layer to one fixed building direction only. This causes limitations of strength properties, surface quality and the need of supporting structures. Multi-axis AM enables completely new design possibilities going beyond current optimization and design strategies of conventional AM workpieces. This innovation requires multiple design and manufacturing changes in the internal and external geometry of the workpiece as well as in machine and printing head technology. This paper identifies the requirements and capabilities of multi-axis AM and presents possible solutions to overcome the identified challenges. Preliminary results for multi-axis AM are described on an exemplary workpiece.

Accuracy design constitutes an important role in machine tool designing. It is used to determine the permissible level of each error parameter of a machine tool, so that any criterion can be optimized. Geometric, thermal-induced, and cutting force-induced errors are responsible for a large number of comprehensive errors of a machine tool. These errors not only influence the machining accuracy but are also of great importance for accuracy design to be performed. The aim of this paper is the proposal of a general approach that simultaneously considered geometric, thermal-induced, and cutting force-induced errors, in order for machine tool errors to be allocated. By homogeneous transformation matrix (HTM) application, a comprehensive error model was developed for the machining accuracy of a machine tool to be acquired. In addition, a generalized radial basis function (RBF) neural network modeling method was used in order for a thermal and cutting force-induced error model to be established. Based on the comprehensive error model, the importance sampling method was applied for the reliability and sensitivity analysis of the machine tool to be conducted, and two mathematical models were presented. The first model predicted the reliability of the machine tool, whereas the second was used to identify and optimize the error parameters with larger effect on the reliability. The permissible level of each geometric error parameter can therefore be determined, whereas the reliability met the design requirement and the cost of this machining was optimized. An experiment was conducted on a five-axis machine tool, and the results confirmed the proposed approach being able to display the accuracy design of the machine tool.