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  Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 294 journals)
    - CERAMICS, GLASS AND POTTERY (26 journals)
    - MACHINERY (33 journals)
    - MANUFACTURING AND TECHNOLOGY (181 journals)
    - METROLOGY AND STANDARDIZATION (4 journals)
    - PACKAGING (15 journals)
    - PAINTS AND PROTECTIVE COATINGS (5 journals)
    - PLASTICS (28 journals)
    - RUBBER (2 journals)

MACHINERY (33 journals)

Showing 1 - 33 of 33 Journals sorted alphabetically
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9)
Advanced Energy Materials     Hybrid Journal   (Followers: 27)
Applied Mechanics Reviews     Full-text available via subscription   (Followers: 26)
BER : Consumer Goods Industries Survey     Full-text available via subscription  
BER : Intermediate Goods Industries Survey     Full-text available via subscription   (Followers: 1)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 2)
CORROSION     Full-text available via subscription   (Followers: 21)
Electric Power Components and Systems     Hybrid Journal   (Followers: 7)
Engenharia Agrícola     Open Access  
Foundations and Trends® in Electronic Design Automation     Full-text available via subscription  
High Speed Machining     Open Access   (Followers: 4)
High Temperature Materials and Processes     Hybrid Journal   (Followers: 6)
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 7)
International Journal of Machining and Machinability of Materials     Hybrid Journal   (Followers: 6)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 8)
International Journal of Precision Technology     Hybrid Journal   (Followers: 1)
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 4)
International Journal of Rotating Machinery     Open Access   (Followers: 2)
Journal of Machinery Manufacture and Reliability     Hybrid Journal   (Followers: 2)
Journal of Machinery Manufacturing and Automation     Open Access   (Followers: 2)
Journal of Modeling in Mechanics and Materials     Partially Free   (Followers: 1)
Journal of Strain Analysis for Engineering Design     Hybrid Journal   (Followers: 8)
Journal of Terramechanics     Hybrid Journal   (Followers: 5)
Machine Design     Partially Free   (Followers: 133)
Machines     Open Access   (Followers: 2)
Materials     Open Access   (Followers: 7)
Mechanics Based Design of Structures and Machines: An International Journal     Hybrid Journal   (Followers: 5)
Micromachines     Open Access   (Followers: 3)
Practical Machinery Management for Process Plants     Full-text available via subscription  
Pump Industry Analyst     Full-text available via subscription   (Followers: 2)
Russian Engineering Research     Hybrid Journal  
Sensor Review     Hybrid Journal   (Followers: 3)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 6)
Journal Cover International Journal of Machine Tools and Manufacture
  [SJR: 2.746]   [H-I: 100]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0890-6955
   Published by Elsevier Homepage  [3048 journals]
  • Machining accuracy improvement of non-orthogonal five-axis machine tools
           by a new iterative compensation methodology based on the relative motion
           constraint equation
    • Authors: Changjun Wu; Jinwei Fan; Qiaohua Wang; Dongju Chen
      Pages: 80 - 98
      Abstract: Publication date: January 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 124
      Author(s): Changjun Wu, Jinwei Fan, Qiaohua Wang, Dongju Chen
      This paper proposes a new iterative compensation methodology of geometric errors to improve the machining accuracy of a non-orthogonal five-axis machine tool (NOFAMT). Firstly, based on homogeneous transform matrix (HTM) and multi-body system (MBS) theory, the relative motion constraint equations (TRMCEs) of the tool tip position and tool orientation vector related to a NOFAMT with a nutating rotary B axis are established. Then, by utilizing TRMCEs, the mapping relationships between tool path and the numerical control (NC) command without and with considering the geometric errors are constructed respectively. In order to truly reproduce tool motion trajectory of the machine tool driven by the given NC command, the mapping relationship between the NC command and tool cutting trajectory is also established. Meanwhile, procedures of iterative compensation are described by using the aforementioned mapping relationships without the traditional inverse calculation, and the actual NC code is generated in self-developed compensation software. It is not difficult to find that the new approach takes the difference between tool path and tool cutting trajectory as the control objective and can directly obtain the actual NC code controlling the machine tool to achieve the desired machining accuracy. Finally, a cutting test is carried out on the DMU60P NOFAMT. Experimental results show the developed iterative compensation methodology is precise and effective for NOFAMTs. Therefore, compared with the existing methods, the new method is more direct and accurate. And its basic idea can be applied to other type of machine tools.

      PubDate: 2017-10-18T02:02:35Z
      DOI: 10.1016/j.ijmachtools.2017.07.008
      Issue No: Vol. 124 (2017)
       
  • Modelling of flow stress by correlating the material grain size and chip
           thickness in ultra-precision machining
    • Authors: M. Azizur Rahman; Mustafizur Rahman; A. Senthil Kumar
      Pages: 57 - 75
      Abstract: Publication date: December 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 123
      Author(s): M. Azizur Rahman, Mustafizur Rahman, A. Senthil Kumar
      Inducing compressive stress on the machined surface is a desirable practice in ultra-precision metal cutting to improve the part quality. An important parameter to analyse the machining performance is the material flow stress, which plays a crucial role in the material deformation characteristics in machining. As the dimensions of the workpiece descend from macro to micro scale in metal forming, the flow stress reduces accordingly. Hence, based on the ‘surface model’ analogy developed for metal forming coupled with the crystal plasticity effect, an attempt has been made in this study to construct a flow stress model for ultra-precision machining process. While developing the model, for the first time, the size factor (η, d/h o ) is introduced to incorporate the material ‘grain size effect’ in ultra-precision machining. The proposed model is validated with experimental results of Al6082 alloy of different grain sizes. Orthogonal turning experiments were conducted on an ultra-precision machine by utilizing the concept of ‘cutting edge radius effect’, which is identified as the relative tool sharpness (RTS) and quantified as the ratio of undeformed chip thickness (h c ) to edge radius (r n ). In this paper, the investigation on the material flow stress is carried out by considering the phenomenon of the shifting material flow separation (cutting) from primary deformation zone to material deformation (ploughing and rubbing) at tertiary deformation zone. The distribution of contact stresses along the tool rake and flank faces at the minimum value of RTS (h c /r n ) of 0.01 substantiates the ploughing effect (compressive stresses are induced into the machined layer) rather than chip separation. Moreover, the distinct variation of the machined surface quality and μ-chip morphology at the extreme low and high RTS conditions distinguishes the material ploughing effect from the cutting effect. Additionally, for the same RTS value, it is found that different grain materials (Cu and Mg alloy) exhibited variations in flow stress, chip morphology and surface quality. Therefore, material grain size is an influential factor for analysing machining performance with material flow stress at ultra-precision level.

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.001
      Issue No: Vol. 123 (2017)
       
  • Calculation model for surface roughness of face gears by disc wheel
           grinding
    • Authors: Yanzhong Wang; Yang Liu; Xiaomeng Chu; Yueming He; Wei Zhang
      Pages: 76 - 88
      Abstract: Publication date: December 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 123
      Author(s): Yanzhong Wang, Yang Liu, Xiaomeng Chu, Yueming He, Wei Zhang
      Face gears have been widely used in the transmission systems of aviation and vehicle as a new form of transmission. In order to improve the bearing capacity and reliability of face gears, it is necessary to study the grinding surface roughness of face gears, so as to guide the grinding process of face gears. A mathematical model of roughness based on disc wheel grinding for face gears is proposed. The model can calculate tooth surface roughness based on grinding machining principle of face gear by disc wheel, considering roughness caused by material removal by grinding wheel wear and the discretized generating movement between grinding wheel and workpiece. Supported by the proposed model, the distribution of surface roughness of face gear is analyzed. The model is verified by experimental data, the influence of grinding parameters on the surface roughness is summarized, and the grinding optimization scheme is put forward.
      Graphical abstract image

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.002
      Issue No: Vol. 123 (2017)
       
  • A selectively-coupled shear localization model for friction stir welding
           process window estimation
    • Authors: Xianjun Pei; Pingsha Dong
      Pages: 89 - 104
      Abstract: Publication date: December 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 123
      Author(s): Xianjun Pei, Pingsha Dong
      This paper presents a novel computational procedure specifically aimed at gaining modeling capabilities for estimating friction stir welding (FSW) process window. The proposed model first combines a three-dimensional (3D) transient heating effects with a one-dimensional (1D) shear localization process leading to shear band development within one pin revolution. The resulting shear band width is then compared with the minimum material flow layer thickness required for satisfying both mass conservation and velocity continuity conditions in a two-dimensional (2D) planar material flow around the tool pin. If the shear band width formed within one pin revolution is equal or larger than the minimum material flow layer thickness, conditions for developing a quality weld prevail. Otherwise, conditions for developing various forms of weld defects can be identified, depending upon shear localization behavior predicted. Specifically, the proposed model is shown capable of elucidating some of the major defect formation mechanisms observed in experiments, such as “lack of fill”, “abnormal stirring”, “surface galling”, and “excessive flash”, etc. As a result, the selectively-coupled shear localization model enables a theoretical estimation of FSW process window typically represented as a regime of welding speed and stir tool rotation speed combination for a given application, within which acceptable weld quality should be expected. Its application in FSW process window estimation is demonstrated by considering three types of aluminum alloys. In all cases, good agreements are achieved between model-estimated and experimentally-determined process windows. In addition, the proposed model also enables a theoretical estimation of optimum welding parameters within an established process window, e.g., for achieving maximum welding speed while maintaining good weld quality.

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.003
      Issue No: Vol. 123 (2017)
       
  • Feasibility study of the novel quasi-elliptical tool servo for vibration
           suppression in the turning of micro-lens arrays
    • Authors: Zhiwei Zhu; Suet To; Wu-Le Zhu; Peng Huang
      Pages: 98 - 105
      Abstract: Publication date: November 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 122
      Author(s): Zhiwei Zhu, Suet To, Wu-Le Zhu, Peng Huang
      In fast or slow tool servo (F-/STS) diamond turning of micro-lens arrays (MLAs), the inherent non-smooth servo motion will lead to undesired tool vibrations, and it can significantly deteriorate the quality of the machined surface. Starting from a mathematical explanation of the underlying mechanism for vibration suppression, a quasi-elliptical tool servo (QETS) technique and the corresponding optimal toolpath determination algorithm are proposed to overcome the inherent defects in F-/STS turning of MLAs. As for the QETS, the inherent non-smooth servo motion in the F-/STS is proposed to be decomposed into two smooth quasi-harmonic motions along the cutting and servo motion directions, which then constructs the quasi-elliptical trajectory. Taking advantage of the smooth nature of the two decomposed motions, the undesired tool vibrations induced by the motion non-smoothness in the F-/STS can be significantly eliminated, accordingly facilitating the generation of MLAs with homogeneous and smooth surfaces. Finally, the new concept is verified through numerical simulation of the tool motion and experimental demonstration by turning a typical hexagonal aspheric MLA.

      PubDate: 2017-07-10T02:38:10Z
      DOI: 10.1016/j.ijmachtools.2017.06.004
      Issue No: Vol. 122 (2017)
       
  • Volumetric accuracy evaluation for five-axis machine tools by modeling
           spherical deviation based on double ball-bar kinematic test
    • Authors: Lei Zhong; Qingzhen Bi; Yuhan Wang
      Pages: 106 - 119
      Abstract: Publication date: November 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 122
      Author(s): Lei Zhong, Qingzhen Bi, Yuhan Wang
      This paper presents a new spherical deviation measurement method to evaluate the volumetric accuracy of five-axis machine tools based on double ball-bar measurements. Nine circular test paths with three kinds of tool axis directions in XY, YZ and ZX planes are planned to construct a typical sphere. The radial deviations measured by ball-bar are used to calculate the spherical deviation, which is defined as the maximum radial range of deviations around a least-squares sphere. Compared to the circular deviation described in ISO10791.6, which could only reflect the errors in one test path with one kinds of tool axis direction separately, the proposed method can reflect not only each test path's error, but also the offset errors between different test paths. And it could comprehensively quantify the effect of accuracies of the five axes together in three-dimensional space. The proposed method for five-axis machine tool can not only reflect the tool center position errors caused by three linear axes, but also indicate the tool axis direction errors caused by two rotary axes. The proposed method is verified through simulations and experiments on a five-axis machine tool.

      PubDate: 2017-07-10T02:38:10Z
      DOI: 10.1016/j.ijmachtools.2017.06.005
      Issue No: Vol. 122 (2017)
       
  • Identification of milling process damping using operational modal analysis
    • Authors: Min Wan; Jia Feng; Ying-Chao Ma; Wei-Hong Zhang
      Pages: 120 - 131
      Abstract: Publication date: November 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 122
      Author(s): Min Wan, Jia Feng, Ying-Chao Ma, Wei-Hong Zhang
      This paper provides a novel approach for identifying the process damping directly from chatter-free milling tests. First, power spectrum density matrix of cutter's deflections is theoretically derived by introducing transfer function and random excitation force, and the spectral decomposition of the power spectrum density matrix is formulated as an explicit function of modal parameters. Then, exponential attenuation method is adopted to extract the damping ratios from the inverse Fourier transformation result of the decomposed form. Finally, tangential and radial ploughing force coefficients, which are utilized to characterize process damping, are simultaneously calculated based on energy balance principle. Besides, experimental setup consisting of displacement sensors is specially designed to measure the cutter's deflections, which are further used to calculate the power spectrum density required in the above identification procedure. It is experimentally proven that the accuracy of chatter stability limits in milling process is improved when the proposed process damping model is considered.

      PubDate: 2017-07-10T02:38:10Z
      DOI: 10.1016/j.ijmachtools.2017.06.006
      Issue No: Vol. 122 (2017)
       
  • An intelligent wheel position searching algorithm for cutting tool grooves
           with diverse machining precision requirements
    • Authors: Guochao Li; Honggen Zhou; Xuwen Jing; Guizhong Tian; Lei Li
      Pages: 149 - 160
      Abstract: Publication date: November 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 122
      Author(s): Guochao Li, Honggen Zhou, Xuwen Jing, Guizhong Tian, Lei Li
      Searching for and adjusting to the appropriate wheel positions for designed grooves are among the key issues in the manufacturing of the end mill, drill and other integral cutting tools. Along with the increasing requirements of product categories and quality, a large number of non-traditional and customized grooves continuously appear. However, as multivariable, nonlinear and multiple target problems, it is difficult to obtain the desired wheel position. Therefore, we introduce an intelligent method to search for the optimum wheel position for the designed groove with the known wheel geometry. According to practice, the basic parameters of the groove and wheel geometries are introduced, and the problems studied in this paper are explained. As a foundation, a robust algorithm is built to predict machined grooves with a series of equal distribution points and three parameters: the rake angle, core radius and groove width. The influence that the wheel positions have on groove geometries is then analyzed. Then, an objective function considering different machining requirements is built, and the optimum wheel positions are searched for while the function is solved. Furthermore, an enhanced niche particle swarm optimization (NPSO) algorithm is developed to solve the problem. Finally, 6 experiments are carried out to verify and analyze the algorithm. The results show that the algorithm can effectively find the desired wheel positions according to different machining precision requirements.

      PubDate: 2017-07-23T10:02:56Z
      DOI: 10.1016/j.ijmachtools.2017.07.003
      Issue No: Vol. 122 (2017)
       
  • Identification of geometric errors of rotary axis on multi-axis machine
           tool based on kinematic analysis method using double ball bar
    • Authors: Hong-jian Xia; Wei-chao Peng; Xiang-bo Ouyang; Xin-du Chen; Su-juan Wang; Xin Chen
      Pages: 161 - 175
      Abstract: Publication date: November 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 122
      Author(s): Hong-jian Xia, Wei-chao Peng, Xiang-bo Ouyang, Xin-du Chen, Su-juan Wang, Xin Chen
      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.

      PubDate: 2017-08-03T05:50:55Z
      DOI: 10.1016/j.ijmachtools.2017.07.006
      Issue No: Vol. 122 (2017)
       
  • Corrigendum to “Theoretical and experimental investigation of spindle
           axial drift and its effect on surface topography in ultra-precision
           diamond turning” [International Journal of Machine Tools &
           Manufacture 116 (2017) 107–113]
    • Authors: Quanhui Wu; Yazhou Sun; Wanqun Chen; Guoda Chen
      Pages: 176 - 178
      Abstract: Publication date: November 2017
      Source:International Journal of Machine Tools and Manufacture, Volume 122
      Author(s): Quanhui Wu, Yazhou Sun, Wanqun Chen, Guoda Chen


      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.05.003
      Issue No: Vol. 122 (2017)
       
  • Identification of workpiece location on rotary tables to minimize tracking
           errors in five-axes machining
    • Authors: Jixiang Yang; Deniz Aslan; Yusuf Altintas
      Abstract: Publication date: Available online 13 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jixiang Yang, Deniz Aslan, Yusuf Altintas
      Five-axis CNC machine tools are widely used in machining parts with free form surfaces. This paper presents optimal placement of parts on the five-axis machine tool tables to minimize the tracking errors of the rotary servo drives. The cutting forces along the tool path are first simulated at the workpiece coordinate system in Computer-Aided-Manufacture (CAM) environment. The cutting torques transmitted to the rotary and translational drives are predicted using the location of the part on the table and kinematic configuration of the machine tool. The optimal location of the part on the table is identified by minimizing the forces transmitted to the rotary drives as torque disturbances. The proposed model has been experimentally validated on a five-axis machine with tilt-table configuration. It has been shown that the tracking and contouring errors can be significantly reduced with the proposed strategy, which can be used by process planners in digital simulation environment.

      PubDate: 2017-11-17T06:48:28Z
      DOI: 10.1016/j.ijmachtools.2017.11.009
       
  • Response to the comment on “International Journal of Machine Tools and
           Manufacture 122 (2017) 66–80”
    • Authors: Wenfeng Ding; Chenwei Dai; Tianyu Yu
      Abstract: Publication date: Available online 11 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Wenfeng Ding, Chenwei Dai, Tianyu Yu


      PubDate: 2017-11-17T06:48:28Z
      DOI: 10.1016/j.ijmachtools.2017.11.008
       
  • 6+X locating principle based on dynamic mass centers of structural parts
           machined by responsive fixtures
    • Authors: Xiaozhong Hao; Yingguang Li; Gengxiang Chen; Changqing Liu
      Abstract: Publication date: Available online 10 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Xiaozhong Hao, Yingguang Li, Gengxiang Chen, Changqing Liu
      Adaptive machining with responsive fixtures is an effective way to release and eliminate deformation during the machining process of large-scale structural parts. While a proper locating principle is a key challenge for the responsive fixture based machining due to its two contradictory requirements of maintaining the machining datum and deformation releasing sufficiently. For traditional machining methods, locators are placed as far as possible from each other to maintain workpiece stability, which would significantly limit the release of workpiece deformation. In order to address the issue mentioned above, different from traditional locating method, a novel 6+X locating principle is proposed in this paper, where the workpiece is divided into a fixed region and a floating region to facilitate the new locating principle. The fixed region is optimized by considering dynamic mass centers with a Genetic Algorithm to maintain workpiece stability, and the 6° of freedom of the workpiece are restrained by the fixed region to keep machining datum. The floating region is supported by X floating units so as to keep the workpiece stable during machining process, while the floating units can adjust the workpiece posture in accordance with the machining deformation during the machining intervals. Algorithm experiments are applied to verify the convergence of the proposed optimization model. Finally, a case study with real machining experiment is carried out to verify the proposed method.

      PubDate: 2017-11-17T06:48:28Z
      DOI: 10.1016/j.ijmachtools.2017.11.006
       
  • Acoustic emission in dressing of grinding wheels: AE intensity, dressing
           energy, and quantification of dressing sharpness and increase in diamond
           wear-flat size
    • Authors: Jeffrey Badger; Stuart Murphy; Garret E. O'Donnell
      Abstract: Publication date: Available online 9 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jeffrey Badger, Stuart Murphy, Garret E. O'Donnell
      Although significant work has been done on the application of acoustic emission (AE) to grinding and to dressing of grinding wheels, several fundamental AE relationships between have not been established. These are: 1) the relationship between dressing energy and the measured AE signal; 2) how different diamond/grit contact modes (fracture, plastic deformation, rubbing, etc.) affect AE energy; and 3) how this can be used to quantify dressing efficiency, wheel sharpness and wear-induced changes in diamond shape. This paper describes an investigation into these fundamental concepts, with quantification of the relationship between AE intensity and dressing energy and the influence of different diamond/grit contact modes. A new parameter is introduced, the specific acoustic-emission dressing energy, which can be used to quantify dressing efficiency and wheel sharpness. Finally, the use of the AE intensity in evaluating diamond wear is explored, allowing the operator to know the size of the wear flat and when changes are necessary to avoid workpiece burn. Experimental work validates these concepts and practical recommendations are given on its application in industry.
      Graphical abstract image

      PubDate: 2017-11-17T06:48:28Z
      DOI: 10.1016/j.ijmachtools.2017.11.007
       
  • Comment on an article
    • Authors: Yuzhou Zhang; Xipeng Xu
      Abstract: Publication date: Available online 7 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yuzhou Zhang, Xipeng Xu


      PubDate: 2017-11-08T20:37:02Z
      DOI: 10.1016/j.ijmachtools.2017.11.005
       
  • Design of thermal error control system for high-speed motorized spindle
           based on thermal contraction of CFRP
    • Authors: Zeji Ge; Xiaohong Ding
      Abstract: Publication date: Available online 7 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Zeji Ge, Xiaohong Ding
      Among the thermal error sources of the high accuracy and efficiency machine tools, the thermal errors induced by the heat generated from running high speed motorized spindle is the crucial one. A new thermal error control method for motorized spindle is suggested, which is based on the thermal deformation balance principle. The essential idea of the method is to utilize the thermal contraction of Carbon Fiber Reinforced Plastic (CFRP) to restrain the thermal elongation of metal spindle housing. In the designed control system, the CFRP bars are uniformly distributed around the spindle housing, and the ThermoElectric Modules (TEMs) works as the heat pump which transfers the heat from spindle housing to CFRP bar. The experimental and numerical simulation results show that the suggested approach reduces 97% thermal displacement compared with the motorized spindle without the suggested thermal error control system. It is expected that the suggested method can also be applied to thermal error control for various cylindrical high-precision parts including aerospace equipment, optics and optical instruments.
      Graphical abstract image

      PubDate: 2017-11-08T20:37:02Z
      DOI: 10.1016/j.ijmachtools.2017.11.002
       
  • Study on variable pressure/position preload spindle-bearing system by
           using piezoelectric actuators under close-loop control
    • Authors: Gaofeng Hu; Dawei Zhang; Weiguo Gao; Ye Chen; Teng Liu; Yanling Tian
      Abstract: Publication date: Available online 6 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Gaofeng Hu, Dawei Zhang, Weiguo Gao, Ye Chen, Teng Liu, Yanling Tian
      Angular contact ball bearings have been widely utilized in machine tool spindles and bearing preload has a great influence on the performance of the spindle. The variable preload control technology, including variable pressure preload and variable position preload, is the key technology for intelligent spindle. In order to implement variable pressure/position preload control, the control method and control performance of the variable pressure/position preload spindle-bearing system by using piezoelectric actuators under close-loop control are systematically studied in this paper. A test rig of variable pressure/position spindle-bearing system is developed, and the piezoelectric actuators are adopted to realized preload or axial clearance close-loop control automatically. Both variable pressure preload and variable position preload can be realized on the test rig. The mechanical model of the variable pressure/position preload spindle-bearing system by using piezoelectric actuators is established. Then stiffness model considering the external axial load in static state, and axial displacement as well as operational preload model in rotational state of the spindle-bearing system with piezoelectric actuators in variable pressure preload and variable position preload are proposed and simulated. The design method of the preload mechanism by using piezoelectric actuators is presented. PI controller is employed to regulate the preload or axial clearance of the spindle-bearing system in real-time. A series of experiments are implemented to verify the validity of the variable preload control method and the superiority of the variable pressure/position preload control performance by using piezoelectric actuators. The results show that the variable pressure/position preload spindle-bearing system by using piezoelectric actuators shows excellent performance in controlling preload or axial clearance. The static and dynamic characteristics as well as the operational behaviors of the spindle-bearing system under variable position preload and variable pressure preload are verified by experiments. It is illustrated that the stiffness and the first order natural frequency will be changed with the change of preload methods and preload values. The variable preload control method plays a great important role on the performance of spindle-bearing system. The operational behaviors varied greatly with the rotational speed and preload or negative axial clearance. Furthermore, this paper provides a foundation for the future research of preloading intelligent control technology as well as investigating the thermal-mechanical-dynamic characteristic of high speed spindle-bearing system.

      PubDate: 2017-11-08T20:37:02Z
      DOI: 10.1016/j.ijmachtools.2017.11.004
       
  • Investigation on the non-coaxiality in the drilling of
           carbon-fibre-reinforced plastic and aluminium stacks
    • Authors: Xiong Liang; Dan Wu; Yuhao Gao; Ken Chen
      Abstract: Publication date: Available online 3 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Xiong Liang, Dan Wu, Yuhao Gao, Ken Chen
      The non-coaxial stacked holes caused by cutting deformation is a common problem in stack drilling, particularly for low-rigidity structure, and the non-coaxiality in carbon-fibre-reinforced plastic and aluminium (CFRP/Al) stack drilling has not been studied. Because of the non-homogeneous behaviour and poor machinability of CFRP, the non-coaxiality in CFRP/Al stack drilling is significantly different from previous studies on Al/Al stack drilling. Focusing on the non-coaxiality in CFRP/Al stack drilling, this paper proposed the mechanism of the non-coaxiality through both experiments and numerical study. Severe non-coaxiality occurrences were observed in the CFRP/Al stack drilling experiments. To explain the observation, the macroscopic mechanics theory of composite was applied to obtain the engineering constants of composite laminates, which are necessary for the numerical model. This application leads to the development of an optimized simulation model to predict the interlayer gaps and non-coaxiality. The numerical results that predict the non-coaxiality are consistent with the experiments, which verified the rationality of simulation model. Furthermore, the effect of the thrust force and clamping force on both interlayer gaps and non-coaxiality were studied. The interlayer gaps gradually increase with the increase in thrust force but decrease with the clamping force. Moreover, the thrust force has a complicated effect on the non-coaxiality. The non-coaxiality first decreases and subsequently increases with the increase in thrust force, which can be attributed to the “tilt effect” in the lower layer. In addition, the non-coaxiality increases with the clamping force in the simulation experiment range. The work in this paper enables us to understand the particularity of the non-coaxiality in CFRP/Al stack drilling and select the appropriate cutting parameters for CFRP/Al stack drilling.

      PubDate: 2017-11-08T20:37:02Z
      DOI: 10.1016/j.ijmachtools.2017.11.001
       
  • Dynamic accuracy evaluation for five-axis machine tools using S trajectory
           deviation based on R-test measurement
    • Authors: Lei Zhong; Qingzhen Bi; Nuodi Huang; Yuhan Wang
      Abstract: Publication date: Available online 3 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Lei Zhong, Qingzhen Bi, Nuodi Huang, Yuhan Wang
      This paper presents a new S trajectory kinematic measurement method to evaluate the dynamic accuracy of five-axis machine tools based on R-test measurements. The S trajectory is obtained by scaling the machining path of the S-shaped test piece to the measuring stroke of the R-test. A geometric and dynamic accuracy simulation model is established to analyze the influence of various error factors on the S trajectory test and compare with the conical kinematic test described in ISO10791.6 quantitatively. The simulation results shown that the S trajectory test is more sensitive to most geometric errors and dynamic errors than the conical test. Particularly, to reflect the dynamic error factors such as poor rigidity of machine tools, servo mismatch, reverse error and nonlinear error, the S trajectory test has obvious advantages. Meanwhile, compared with the actual S-shaped piece machining, which is under development for inclusion in ISO 10791.7, the proposed non-cutting kinematic test method can simply reflect the dynamic accuracy of five axis machine tools itself without the interference of other factors and does not require additional workpiece and testing equipment. The proposed method is verified through experiments on a five-axis machine tool.

      PubDate: 2017-11-08T20:37:02Z
      DOI: 10.1016/j.ijmachtools.2017.11.003
       
  • A review of contouring-error reduction method in multi-axis CNC machining
    • Authors: Zhen-yuan Jia; Jian-wei De-ning Song Fu-ji Wang Wei Liu
      Abstract: Publication date: Available online 26 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Zhen-yuan Jia, Jian-wei Ma, De-ning Song, Fu-ji Wang, Wei Liu
      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.

      PubDate: 2017-11-03T04:26:14Z
       
  • A new diamond machining approach for extendable fabrication of
           micro-freeform lens array
    • Authors: Wu-Le Zhu; Fang Duan; Xiaodong Zhang; Zhiwei Zhu; Bing-Feng Ju
      Abstract: Publication date: Available online 25 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Wu-Le Zhu, Fang Duan, Xiaodong Zhang, Zhiwei Zhu, Bing-Feng Ju
      Fast tool servo diamond turning is conventionally a spiral path-based process widely used to efficiently fabricate non-rotationally symmetric surfaces with ultra-fine accuracy. However, the technique is naturally restricted by the demanding bandwidth and resolution requirements, which are directly related to the complexity and size of the machining surface. Moreover, non-smooth trajectories required for machining complex lens array with discontinuities, due to overlapping sharp edges, induce vibrations causing the surface quality to deteriorate, and adding additional barriers to using this conventional technique in broader applications. In this paper, a new diamond machining approach is proposed to address its inherent drawbacks. Using the new method, complex lens array consisting of arbitrary lenslet shapes could be fabricated in an extendable way without the typical limitations. Theoretical investigations of the unique cutting kinematics, motion determination, servo synchronization and compensation will be carried out. To predict the machined surface topography, the surface generation mechanism with consideration of both the kinematic tool/workpiece interaction and elastic recovery of materials is presented. The experimental fabrication of hexagonal micro-sphere lens array, micro-freeform lens array, as well as seamlessly stitched sinusoidal surface with quadrupled areas was highly consistent and aligned with the theoretical predictions, thus demonstrating the effectiveness of the new approach and its potential for broader applications.

      PubDate: 2017-10-26T07:35:53Z
      DOI: 10.1016/j.ijmachtools.2017.10.007
       
  • An experimental study of surface layer removal mechanisms for epoxies with
           two different crosslink density
    • Authors: H. Wang; L. Chang; Y.-W. Mai; L. Ye; J.G. Williams
      Abstract: Publication date: Available online 16 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): H. Wang, L. Chang, Y.-W. Mai, L. Ye, J.G. Williams
      In this study, we investigate the machining behaviour of a Piperidine and a MDA cured DGEBA epoxy resin under low speed orthogonal micro-cutting conditions. The characteristics of chip-workpiece separation, chip formation and machined surface damage were examined in association with thermomechanical and mechanical properties of the epoxies. It is found that the separation of the chip from the workpiece takes place by fracture, according to Williams' model of machining. Further, cube-square scaling principles can be used to explain the mechanism of the observed brittle-to- ductile cutting behaviour of the epoxies. The results also show that the chip formation process is determined by both shear yielding and plastic bending behaviour of the material. In particular, chip formation involves the imposition of large strain plastic deformation. This explains the dependence of the cutting states (such as continuous chip and broken chip) on the degree of crosslink density of the epoxy, since the latter controls the post-yield deformability of epoxy chips. Based on our new findings, a modified Williams' cutting model is proposed to account for the chip formation behaviour of polymers in cutting.

      PubDate: 2017-10-18T02:02:35Z
      DOI: 10.1016/j.ijmachtools.2017.10.003
       
  • Calibration and compensation of machine tool volumetric error using a
           laser tracker
    • Authors: An Wan; Libin Song; Jing Xu; Shaoli Liu; Ken Chen
      Abstract: Publication date: Available online 14 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): An Wan, Libin Song, Jing Xu, Shaoli Liu, Ken Chen
      Machine tools are widely used in industrial manufacturing. Volume positioning error calibration and compensation are important for ensuring manufacturing accuracy. However, there are two challenges associated with traditional methods. First, the machine tool coordinate system and measurement system must be registered before measuring, but the existing registration methods cannot manage the anisotropic situation, leading to low registration accuracy. To solve this problem, a closed-form iteration combined weighting method is developed. Second, the verification of volumetric error in the entire workspace usually requires hundreds of measurements, which makes the measurement process very complex and time-consuming and possibly affects the calibration accuracy. To this end, a Gaussian process regression (GPR)-based volumetric error prediction and compensation method is improved to simplify the measurement process and ensure accurate calibration and compensation. Simulations and experiments show that the proposed closed-form iteration combined weighting method can improve the registration accuracy, and the proposed GPR-based volumetric error prediction and compensation method can achieve high accuracy with a simple measurement process. Therefore, the proposed methods provide an effective path for machine tool volume positioning error calibration and compensation.

      PubDate: 2017-10-18T02:02:35Z
      DOI: 10.1016/j.ijmachtools.2017.10.004
       
  • Two-step electromagnetic forming: A new forming approach to local features
           of large-size sheet metal parts
    • Authors: Hongliang Liang; Huang Jianjun Fei Pan Huang Fei Feng
      Abstract: Publication date: Available online 12 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Hongliang Su, Liang Huang, Jianjun Li, Fei Ma, Pan Huang, Fei Feng
      A new two-step electromagnetic forming (two-step EMF) which combines electromagnetic forming (EM forming) with electromagnetic calibration (EM calibration), is proposed for local features of large-size sheet metal parts, such as an oblique hole-flanging. During the process, the workpiece is firstly electromagnetic formed by a flat spiral coil and then electromagnetic calibrated by a helix coil with a similar shape to the final profile of the workpiece. To develop the process, an efficient geometric design method is established, the effects of key process parameters on forming quality are investigated, and the deformation behavior of the workpiece is revealed. The feasibility of two-step EMF is validated by the accurate oblique hole-flanging with a maximum die-fitting gap less than 0.2 mm. Moreover, experimental results show that there are critical discharge voltages for both EM forming and EM calibration which lead to the minimum die-fitting gap. Furthermore, EM calibration can reduce the die-fitting gap to 0.24–1 times of that for EM forming with more uniform distribution. In addition, simulation results show that during EM calibration, the stress distribution of the workpiece is improved, the bending moment is reduced which is responsible for the shape and size errors, then the rebound is restricted. Consequently, the fittability and forming accuracy are significantly enhanced.
      Graphical abstract image

      PubDate: 2017-10-18T02:02:35Z
       
  • Real-time local smoothing for five-axis linear toolpath considering
           smoothing error constraints
    • Authors: Jie Huang; Li-Min Zhu
      Abstract: Publication date: Available online 7 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jie Huang, Xu Du, Li-Min Zhu
      Five-axis linear toolpaths (or G 01 blocks) are widely used in CNC machine tools. The tangential and curvature discontinuities at the corners of linear toolpath result in feed fluctuation and deteriorate the machining efficiency and quality. Several methods have been proposed to locally smooth the corners for three-axis toolpath, but local smoothing for five-axis toolpath is still challenging due to two main difficulties: control of the tool orientation smoothing error and parameter synchronization between tool position and tool orientation. This paper proposes a real-time G 2 continuous local smoothing method by replacing the corners of tool position and tool orientation paths with cubic B-splines. The two difficulties in five-axis local smoothing are both resolved in simple and analytical ways. With a two-step method, the tool orientation smoothing error is directly and analytically constrained. By converting the remaining linear segments into B-splines, the C 1 continuity of the smooth tool position and smooth tool orientation paths is achieved. The parameter synchronization is realized by sharing the parameter of the tool orientation with that of the tool position. Compared with the existing analytical methods, the proposed method has a higher computation efficiency and a tighter tolerance in control of the orientation smoothing error. We have developed an open-source benchmark which validates the computation efficiency and error control ability of the proposed method. After smoothing and synchronization, the inserted B-spline of tool position is traversed with constant feedrate and the feedrate of the remaining linear segment is planned with jerk-bounded trajectory profile. The proposed smoothing method can be implemented on-line and has been integrated into a self-developed open-architecture CNC system. Its effectiveness for on-line generating smooth motion has been validated via simulations and experiments.

      PubDate: 2017-10-11T06:43:59Z
       
  • Stiffness variation method for milling chatter suppression via
           piezoelectric stack actuators
    • Authors: Chenxi Wang; Xingwu Zhang; Yilong Liu; Hongrui Cao; Xuefeng Chen
      Abstract: Publication date: Available online 6 October 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Chenxi Wang, Xingwu Zhang, Yilong Liu, Hongrui Cao, Xuefeng Chen
      In cutting process, chatter is an inevitable phenomenon that greatly affects workpiece surface quality, tool life and machining efficiency. The stiffness variation (SV) method has been proposed and applied in chatter suppression for a long time. However, the early studies focused on boring and turning with one degree of freedom. For milling process with two degrees of freedom, there is no related research about SV. In this paper, SV method is employed through modulating the stiffness around a nominal value in order to suppress milling chatter. The milling dynamic model of SV with two degrees of freedom is constructed. In this model, the classical delay differential equation (DDE), which governs the milling process, is replaced with a DDE with a time-varying stiffness term. The stability analysis with different SV is completed using the semi-discretization method (SDM) and results show that the stable region with SV is larger than that under most of the traditional conditions. The results of stability analysis are verified by time domain simulation. In addition, the influences on stability lobe diagram (SLD), which is caused by different waveforms, amplitudes and frequencies of SV, are also analyzed specifically. The analysis results can provide the optimal parameters combination for milling. Cutting experiments are implemented on a three-axis milling machine to validate the effectiveness of SV. In the experiment, piezoelectric stack actuators are used to modulate the stiffness with time-varying preload. The milling forces signals are acquired by data collecting instrument, whose root-mean-square (RMS) is used as the metric of cutting vibrations. Experiment results are in good agreement with theoretical prediction.

      PubDate: 2017-10-11T06:43:59Z
      DOI: 10.1016/j.ijmachtools.2017.10.002
       
  • Modification of tool influence function of bonnet polishing based on
           interfacial friction coefficient
    • Authors: Ri Pan; Bo Zhong; Dongju Chen; Zhenzhong Wang; Jinwei Fan; Chunyan Zhang; Sinan Wei
      Abstract: Publication date: Available online 28 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Ri Pan, Bo Zhong, Dongju Chen, Zhenzhong Wang, Jinwei Fan, Chunyan Zhang, Sinan Wei
      Aimed to improve the modeling accuracy of tool influence function (TIF) of bonnet polishing, a theoretical and experimental study is presented. This paper starts with the affecting mechanism of key parameters on the material removal of workpiece. It is indicated that the interfacial friction coefficient between tool and workpiece is changed with the variety of the tool rotational speed, which impacts the TIF but has not been taken into account in most current TIF models. Consequently, modification of TIF model based on the interfacial friction coefficient is proposed and then experimentally validated. The results show that, for the experimental groups in which the spot size is 15 mm, the difference between the maximum removal depth of the TIF predicted with the pre-modified model and that of the experimental TIF is −0.204–1.244λ (λ = 632.8 nm), which is obviously larger than that between the TIF predicted with the modified model and the experimental TIF-0.187–0.168λ. Moreover, for the experimental groups in which the spot size is 20 mm, the difference between the maximum removal depth of the TIF predicted with the pre-modified model and that of the experimental TIF is −0.135–2.235λ, while that between the TIF predicted with the modified model and the experimental TIF is −0.046–0.571λ. The experimental results indicated that the TIF predicted by the modified model is much closer to the experimental TIF, which proves the effectiveness and correctness of the modification.

      PubDate: 2017-10-04T06:48:35Z
      DOI: 10.1016/j.ijmachtools.2017.09.003
       
  • Evaluation of machine tools with position-dependent milling stability
           based on Kriging model
    • Authors: Congying Deng; Jianguo Miao; Bo Wei; Yi Feng; Yang Zhao
      Abstract: Publication date: Available online 28 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Congying Deng, Jianguo Miao, Bo Wei, Yi Feng, Yang Zhao
      Machine tool's milling stability is a function of the frequency response function (FRF) at the tool tip, which varies with the position changes of the moving components within the machine tool work volume. The approach to obtain stability lobe diagram avoiding chatter vibrations is generally based on some specific positions, resulting in an incomprehensive and inaccurate chatter prediction. This paper presents a new method to rapidly evaluate the position-dependent milling stability of machine tools. In this method, position combinations of the moving components are arranged to perform the impact testing, and then the corresponding identified FRFs at the tip of machine tool frame-holder base are acquired to identify the modal parameters, with which a Kriging model is developed to describe the relationship between positions and modal parameters. Consequently, based on the modal fitting technique, tip FRFs of machine tool frame-holder base at any position in the whole working space can be reorganized. And such tip FRFs are further adopted to calculate the tool tip FRFs with the identified contact parameters of the holder-tool system using the receptance coupling substructure analysis (RCSA) technique. Then, the milling stability at different positions can be assessed. Furthermore, the proposed method is applied to a vertical machining center, and its accuracy for predicting the milling stability in entire work volume is validated through chatter tests.

      PubDate: 2017-10-04T06:48:35Z
      DOI: 10.1016/j.ijmachtools.2017.09.004
       
  • An improved fix-length compensation method for electrical discharge
           milling using tubular tools
    • Authors: Jingyu Pei; Xiaoshun Zhuang; Lenan Zhang; Yetian Zhu; Yebin Liu
      Abstract: Publication date: Available online 28 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jingyu Pei, Xiaoshun Zhuang, Lenan Zhang, Yetian Zhu, Yebin Liu
      Due to inevitable wear of electrodes in micro electrical discharge machining (μEDM), compensation of tools is of great importance to maintain machining accuracy. Among all of the compensation strategies, fix-length compensation method is one of the most efficient ways for cavity milling because large single layer thickness can be achieved. However, previous studies have shown that slots with triangle-shape cross section are formed, and extra processing has to be performed to remove the surface fluctuations, which degrade machining accuracy and lower total efficiency. To improve the traditional fix-length compensation method, in this work, the cylindrical tool is replaced by the tubular tool, and a truncated conic tool end is observed in experiments. An analytical model is then developed relating the truncated conic shape to fix-length compensation parameters. This analytical model is then used to determine the machining parameters, which correspond to a preset milling depth. The effects of key parameters on plane machining are predicted by the analytical model and verified through double slots machining experiments, which show high machining accuracy can be reached under any overlapping ratios and target depths. Finally, the presented machining method is further validated by machining a rectangular cavity and a cavity with a circular pattern. Machining results prove the depth accuracy of the proposed method can be controlled within 4 μm.

      PubDate: 2017-10-04T06:48:35Z
      DOI: 10.1016/j.ijmachtools.2017.09.005
       
  • Effects of pin thread on the in-process material flow behavior during
           friction stir welding: A computational fluid dynamics study
    • Authors: Gaoqiang Chen; Han Li; Shuai Zhang; Qilei Dai; Xibo Wang; Gong Zhang; Qingyu Shi
      Abstract: Publication date: Available online 15 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Gaoqiang Chen, Han Li, Shuai Zhang, Qilei Dai, Xibo Wang, Gong Zhang, Qingyu Shi
      Pin thread is one of the most common geometrical features for the friction stir welding (FSW) tools. The main purpose of employing the pin thread is to improve the in-process material flow behaviors during FSW. However, it has not been fully understood how exactly the pin thread influences the material flow because of the lack of in-process observation. In this study, we aim to analyze the effect of pin thread on the in-process material flow during FSW of an AlMgZn alloy by using numerical simulation based on computational fluid dynamics (CFD). In our numerical simulation, the transient rotation of the threaded pin is implemented explicitly via fully transient control of the zone motion, and the mechanical interaction at the tool-workpiece interface is considered via the recent developed shear-stress-based frictional boundary condition. The numerical simulation has been validated by the experimental measured temperatures at 8 different locations, the distribution of marker materials and the geometry of deformation zone in the weld. Based on the numerical simulation results, three effects of the pin thread on the material flow have been elucidated. First, accelerated flow velocity and enhanced strain rate is induced owing to the use of the pin thread, which is attributed to the fact that the interfacial sticking is preferable inside the thread groove opening. Second, the pin thread has an effect to trap material in the high-velocity zone inside the thread groove opening, which causes a many-circle flow pattern around the threaded pin. Third, the pin thread contributes to a vertical pressure gradient, which is important for the in-process material transfer from the top to the bottom. The approaches and concepts in this study can be applied for further fundamental investigation of FSW and the computer aided design of the welding tools.

      PubDate: 2017-09-19T12:33:08Z
      DOI: 10.1016/j.ijmachtools.2017.09.002
       
  • A new physics-based model for equilibrium saturation determination in
           binder jetting additive manufacturing process
    • Authors: Hadi Miyanaji; Shanshan Zhang; Li Yang
      Abstract: Publication date: Available online 11 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Hadi Miyanaji, Shanshan Zhang, Li Yang
      In binder jetting additive manufacturing (BJ-AM) process, the features are created through the interaction between droplets of the liquid binding agent and the layered powder bed. The amount of binder, which is termed binder saturation, depends strongly on the liquid binder and powder bed interaction including the spreading (i.e. lateral migration) and penetration (vertical migration) of the binder in powder bed, and is of crucial importance for determining the accuracy and strength of the printed parts. In the present study, a new physics-based model is developed to predict the optimal saturation levels for the green part printing, which is realized via capillary pressure estimation that is based on the binder and powder bed interactions in the equilibrium state. The proposed model was evaluated by both the Ti6Al4V and 420 stainless steel powders that exhibit different powder characteristics and packing densities. In order to estimate the equilibrium saturation using the proposed model, the physical characteristics such as average contact angle between the binder and powder material, specific surface area of powder particles, saturation and capillary pressure characterization curve were determined. Features with various degrees of dimensions (1-D, 2-D, 3-D) were printed out using M-Lab ExOne printer for determining the equilibrium saturation. Good agreement was observed between the theoretical predictions and experimentally measured saturation levels for the Ti6Al4V powder. On the other hand, the model underestimated the optimal saturation level for the 420 stainless steel powder, which was likely caused by the micro-surface areas from powder particle surface that do not contribute to the binder-powder bed interactions.

      PubDate: 2017-09-13T12:25:14Z
      DOI: 10.1016/j.ijmachtools.2017.09.001
       
  • Multi-dimensional chatter stability for enhanced productivity in different
           parallel turning strategies
    • Authors: Milad Azvar; Erhan Budak
      Abstract: Publication date: Available online 1 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Milad Azvar, Erhan Budak
      Simultaneous turning with extra cutting edges increases the material removal rate (MRR), and thus the productivity of the process. On one hand, chatter could be a fatal threat to the productivity and part quality in simultaneous turning operations of slender and flexible workpieces. On the other hand, stability of flexible part turning can be increased significantly if the process parameters are selected properly. In practice, however, ensuring a stable parallel turning of a flexible workpiece is approached by the costly process of trial and error. In order to tackle this problem, a multi-dimensional model for chatter stability analysis of parallel turning operation is presented where the effects of components' dynamics, i.e. workpiece and cutters, in addition to insert's geometry are accounted for. The stability model is formulated for two configurations of the parallel turning operation in frequency and time domains, and verified experimentally. Chatter-free and high productivity cutting conditions are determined through optimal parameter selection employing stability maps generated for each configuration.

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.005
       
  • An efficient error compensation method for coordinated CNC five-axis
           machine tools
    • Authors: Dan Zhao; Yunbo Bi; Yinglin Ke
      Abstract: Publication date: Available online 1 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Dan Zhao, Yunbo Bi, Yinglin Ke
      The paper introduces a new automatic drilling and riveting system for aircraft assembly which is composed of two five-axis machine tools in coordination. As a dual-machine system, relative position and orientation accuracy of coordinated machines is the decisive factor for high fastening quality. Considering all static/quasi-static error sources deteriorating relative positioning accuracy, an effective error compensation method which consists of a new error prediction model and an error compensation strategy is proposed for coordinated five-axis machines. Based on the decomposition concept, the coordinated workspace of dual machines is described as the superposition of the coordinated workspace of prismatic joints (CWP) and the coordinated workspace of revolute joints (CWR). They are separated to study the influence on the objective error, and a combined interpolation algorithm based on the shape functions is proposed for error prediction, which can avoid the curse of dimensionality essentially and be efficient to predict the relative position and orientation errors at any desired pose in the coordinated workspace of dual machines. For the error compensation of dual-machine system, a basic strategy is proposed which is to take the position and orientation of the driving machine as the reference and compensate the predicted error for the driven machine through the motion commands modification. To verify the feasibility of proposed method, experiments have been performed on the developed dual-machine system with different error compensation methods. The results show that the proposed method is more efficient which needs less time for sampled data measurement and calculation, and the relative positioning accuracy of the compensated dual-machine system is improved to 0.072 mm and 0.017° which meet the requirements for automatic drilling and riveting in aircraft assembly.

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.007
       
  • Cutting temperature and resulting influence on machining performance in
           rotary ultrasonic elliptical machining of thick CFRP
    • Authors: Daxi Geng; Zhenghui Lu; Guang Yao; Jiajia Liu; Zhe Li; Deyuan Zhang
      Abstract: Publication date: Available online 1 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Daxi Geng, Zhenghui Lu, Guang Yao, Jiajia Liu, Zhe Li, Deyuan Zhang
      As a novel non-conventional machining process, rotary ultrasonic elliptical machining (RUEM) has been successfully used for drilling thick carbon fiber-reinforced plastics (CFRPs) recently. In order to reduce the thermal damage, the measurement of cutting temperature is important when RUEM of CFRP. In this research, the cutting temperatures in both RUEM and grinding drilling (GD) were measured by an infrared camera under dry condition. Temperature trends as functions of feed rate and cutting speed were obtained and the results showed that compared to GD, RUEM can effectively reduce the maximum temperature by 18.8% and 13.1% at the feed rate of 75 and 150 μm/rev respectively. Both mechanisms of temperature reduction and chip adhesion prevention in RUEM were analyzed. In addition, SEM observation of the machined surface revealed that better microstructure was obtained in RUEM compared to GD under the same cutting condition.

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.008
       
  • Mechanics and multi-regenerative stability of variable pitch and variable
           helix milling tools considering runout
    • Authors: Jinbo Niu; Ye Ding; LiMin Zhu; Han Ding
      Abstract: Publication date: Available online 1 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jinbo Niu, Ye Ding, LiMin Zhu, Han Ding
      Variable pitch and variable helix (VPVH) milling tools are usually utilized to mitigate regenerative chatter vibrations by destroying the vibration phases between adjacent teeth. But this chatter suppression mechanism may considerably be disturbed by the inevitable tool runout, which could also change the phases, even to a larger extent. Thus the cutting performance of VPVH tools in terms of mechanics and dynamics should be re-evaluated by taking runout into consideration. This paper firstly sets up the mechanistic model for VPVH tools and then presents a combined nonlinear optimization procedure to identify the cutting coefficients and runout parameters. Secondly, the dynamic system of VPVH tools considering runout is modeled by a periodic-coefficient delay differential equation with multiple underdetermined delays. Afterwards, the generalized Runge-Kutta (GRK) method is extended to tackle the runout-induced multi-regenerative effects and thus to analyze the milling process stability. The accuracy and efficiency of the GRK method is validated using published numerical examples. A series of cutting experiments with a commercially available VPVH tool are performed to verify the presented mechanistic and dynamic models. It confirms that runout cannot be neglected when evaluating the cutting performance of VPVH tools. Finally, the joint influences of runout and pitch/helix angles on cutting forces and chatter stability of VPVH tools are discussed in detail based on the proposed approach.

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.006
       
  • Flow behavior of powder particles in layering process of selective laser
           melting: Numerical modeling and experimental verification based on
           discrete element method
    • Authors: Hui Chen; Qingsong Wei; Shifeng Wen; Zhongwei Li; Yusheng Shi
      Abstract: Publication date: Available online 1 September 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Hui Chen, Qingsong Wei, Shifeng Wen, Zhongwei Li, Yusheng Shi
      Powder-layering is an essential process of selective laser melting (SLM), but the underlying mechanisms of powder movement and packing at particle scale is unclear. Based on discrete element method (DEM), this study proposed a numerical model to investigate the flowing behavior of powder layered by a blade, where the contact force and cohesion force between individual particles were considered. DEM simulations gave visual morphologies of the flow profiles and velocity fields for powder-layering at particle scale, as well as the relationships between the quality of powder bed and the layering parameters. The model was validated by experiment results in terms of the macroscopic profiles of powder during layering, showing good prediction accuracy. Then, dynamic repose angle (DRA) and mass flow rate (MFR) were defined to make quantitative evaluation on the powder flow. Preliminary research shows that, the powder fluidity increases with the decreasing of particle friction coefficients, resulting in a denser and more uniform powder bed. The decreasing of particle radius R over the range of R > 21.8 μm can benefit the powder fluidity. However, when the particle radius decreases in the range of R < 21.8 μm, the weight of cohesion force rises and thus makes the powder fluidity worse. The increase of layering speed enhances the dilation of moving particles, and the decrease of layering height intensifies the local force-arches in particles. These will reduce the continuity and stability of the powder flow and is unfavorable for improving the density or uniformity of the layered powder bed.
      Graphical abstract image

      PubDate: 2017-09-02T14:20:40Z
      DOI: 10.1016/j.ijmachtools.2017.08.004
       
  • An analytical local corner smoothing algorithm for five-axis CNC machining
    • Authors: Jixiang Yang; Alexander Yuen
      Abstract: Publication date: Available online 31 July 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jixiang Yang, Alexander Yuen
      Linear motion commands of computer numerical control (CNC) machine tools need to be smoothed at the transition corners in order to guarantee continuous and steady machining. However, because of the complex kinematic constraints, very few researches have devoted to developing analytical and high order continuous corner smoothing algorithms of five-axis tool paths, although it is important to guarantee both high calculation efficiency and good dynamic performance of five-axis CNC machining. This paper develops an analytical C 3 continuous corner smoothing algorithm of five-axis tool paths by locally inserting specially designed quintic micro splines into the transition corners of five-axis linear commands. C 3 continuity of the tool tip position and the tool orientation are guaranteed along the entire tool path. The maximal approximation errors of the tool tip position and the tool orientation are both constrained in the workpiece coordinate system. The synchronization of the tool tip position and tool orientation are mathematically guaranteed at the junctions of the linear and spline segments. The proposed corner smoothing algorithm can calculate all control points of the locally inserted tool tip position and tool orientation splines analytically without any iteration, which makes it very suitable to on-line calculation. Experiments on an in-house developed five-axis CNC platform verify that the maximal approximation errors of both tool tip position and tool orientation are constrained, and the proposed C 3 continuous corner smoothing algorithm has higher tracking accuracy and lower acceleration frequency content at higher frequencies than the C 2 continuous algorithm.

      PubDate: 2017-08-03T05:50:55Z
      DOI: 10.1016/j.ijmachtools.2017.07.007
       
  • Theoretical and experimental study of magnetic-assisted finish cutting
           ferromagnetic material in WEDM
    • Authors: Zhi Chen; Yanming Zhang; Guojun Zhang; Yu Huang; Chunhua Liu
      Abstract: Publication date: Available online 30 July 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Zhi Chen, Yanming Zhang, Guojun Zhang, Yu Huang, Chunhua Liu
      A method of magnetic assisted finish cutting ferromagnetic material is proposed to improve machining performance in WEDM, and theoretical and experimental study of this method is implemented to illustrate its improving mechanism. Firstly, the motion trajectory model of electron beam is presented for the first time to clarify the effect of constant magnetic field on increasing the discharge crater in single pulse discharge process, and theoretical model and experiment indicate that additional constant magnetic field can efficiently suppress the divergence phenomenon, increase energy density of electron beam and shorten discharge gap breakdown time. Secondly, the charged debris motion curve of magnetic assisted finish cutting is worked out, and it reveals that more charged debris can be washed away when the direction of Lorentz force is the same with dielectric flushing. Additionally, a set of experiment is accomplished to investigate the improving effect of constant magnetic field, and experiment result represents that significantly improvement (material removal rate (MRR) maximum increase by 44.0%, and surface roughness (Ra) maximum reduce by 30.5%) has been obtained. Eventually, by the method of multi-objective optimization, a group of Pareto optimal set of MRR and Ra is worked out to satisfy different requirement of practical manufacture.

      PubDate: 2017-08-03T05:50:55Z
      DOI: 10.1016/j.ijmachtools.2017.07.009
       
  • A multiscale evaluation of the surface integrity in boring trepanning
           association deep hole drilling
    • Authors: Huang Zhang; Xingquan Shen; Arixin Bo; Yaoming Li; Haifei Zhan; Yuantong Gu
      Abstract: Publication date: Available online 23 July 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Huang Zhang, Xingquan Shen, Arixin Bo, Yaoming Li, Haifei Zhan, Yuantong Gu
      Boring trepanning association (BTA) deep hole drilling is one of the most important manufacturing techniques to produce a large length-to-diameter ratio hole for industrial applications. In addressing the challenge of excessive surface damage, inefficiency and poor indexing in BTA deep hole drilling, for which there are limited studies reported. The functional behaviour of deep hole machining and the correlation between the machined surface quality, subsurface layer deformation and the machining conditions are investigated in this paper, together with the drilling mechanism. Various parameter combinations are used to produce different samples on which surface roughness and microstructures are studied. Metallurgical characterization is performed on the subsurface regions, followed by qualitative and quantitative mechanical nanohardness investigations. Electron microscopic analysis reveals various surface features such as grooves and plateaus, folding, material flaking that are exclusive to deep hole drilling. It has been found that improved surface integrity in BTA drilling relies on a trade-off among feedrates and speeds. Although considered sample dependent, combination of a feedrate of 28 mm min−1 and a speed of 630 r min−1 can produce nearly excellent surface integrity. Grain structure observations over the subsurface reveal three different layered zones including an ultrafine grain structure layer, a transitional grain structure layer and a substrate material layer. A significantly hardened (56% increase) surface layer on cutting-and-burnishing region comparing with the solely cutting region is detected. The subsurface grain features are induced by repeated thermo-mechanical functioning that causes grain refinement and thus materials hardening. The different surface integrities are the result of comprehensive functions of the machining parameters and combined drilling mechanism.

      PubDate: 2017-08-03T05:50:55Z
      DOI: 10.1016/j.ijmachtools.2017.07.005
       
  • State-of-the-art in fixture systems for the manufacture and assembly of
           rigid components: A review
    • Authors: A. Gameros; S. Lowth; A. Dragos; A. Nagy-Sochacki; O. Craig; H.R. Siller
      Abstract: Publication date: Available online 22 July 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): A. Gameros, S. Lowth, A. Dragos, A. Nagy-Sochacki, O. Craig, H.R. Siller
      Basic work holding devices (e.g. vices), fixtures and jigs are used to construct a critical interface between a workpiece and an end-effector. This interface performs two main functions: location of the workpiece in the Euclidean space and preservation of the workpiece position against any loads. Despite the critical nature of the part-machine interface, limited attention has been given to work holding systems in the academic community. In this respect, the main objective of this paper is to systematically review the field of fixture design, thus allowing the classification of fixturing systems to identify research trends and niches. This review is broken into four sections: (i) basics of fixturing and work holding; (ii) fixtures for single components. The classification of these systems is based on an evolutionary trend that allows to see how the development of technologies, such as additive manufacture, sensing technologies and actuation systems, affects fixture design; (iii) fixtures for multi-parts (both for batch production and assembly operations), with an emphasis on the unique challenges that arise from the assembling process; and (iv) conclusions, denoting various research trends/opportunities in the areas of fixture design and fixture instrumentation. Examples of these prospects includes the integration of fixtures with sensing technology (incentivise by the growth of industry 4.0) and the construction of truly new multi-part fixturing systems, rather than just the expansion of single component fixtures.

      PubDate: 2017-08-03T05:50:55Z
      DOI: 10.1016/j.ijmachtools.2017.07.004
       
  • Study on position of laser cladded chip breaking dot on rake face of HSS
           turning tool
    • Authors: Chenchun Shi; Aibing Yu; Jianzhao Wu; Weiyang Niu; Yuan He; Xin Hong; Quanbo Shang
      Abstract: Publication date: Available online 6 July 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Chenchun Shi, Aibing Yu, Jianzhao Wu, Weiyang Niu, Yuan He, Xin Hong, Quanbo Shang
      Chip breaker with a raised dot was fabricated on the rake face of high speed steel (HSS) turning tool using laser powder cladding method. Based on chip breaking condition and chip breaking dot position conditions, three position equations of laser cladded chip breaking dot were established. The theoretical position regions of laser cladded chip breaking dot on rake face of tool were determined. Turning experiments of aluminum alloy were carried out. Chip breaking processes were observed with high-speed camera. The calculated position regions of chip breaking dot are in good agreement with the experimental results. Turning tool with chip breaking dot located in the position region on rake face has effective chip breaking ability. There also exists a transition position region of chip breaking dot. The position regions could provide reference for the fabrication of laser cladded chip breaking dot on rake face of HSS cutting tools.

      PubDate: 2017-07-10T02:38:10Z
      DOI: 10.1016/j.ijmachtools.2017.07.001
       
  • Grinding performance of textured monolayer CBN wheels: Undeformed chip
           
    • Authors: Wenfeng Ding; Chenwei Dai; Tianyu Yu; Jiuhua Xu; Yucan Fu
      Abstract: Publication date: Available online 13 June 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Wenfeng Ding, Chenwei Dai, Tianyu Yu, Jiuhua Xu, Yucan Fu
      The ground surface roughness and topography are commonly used to characterize the surface finishing. In the application of textured monolayer CBN wheels, the nonuniformity of wheel topology will render a nonuniform undeformed chip thickness which greatly affects the ground surface. In order to predict the ground surface topography more accurately and efficiently, grinding experiment has been conducted in the current study, with measured grinding wheel topology. The measured surface topology of textured monolayer CBN wheels have been reconstructed by using the Johnson transformation and its inverse transformation. The influence of wheel topology evolution on the undeformed chip thickness nonuniformity has been determined with an improved model. It has been found the ground surface roughness is improved with a continuous reducing undeformed chip thickness nonuniformity. The percentage of active grains, the mean value and standard deviation of undeformed chip thickness have been found the main factors in determining the surface roughness. The reconstructed wheel surface topology has been used to predict the workpiece topography in different stages of the grinding process.

      PubDate: 2017-06-15T13:23:09Z
      DOI: 10.1016/j.ijmachtools.2017.05.006
       
  • Analysis of grinding mechanics and improved predictive force model based
           on material-removal and plastic-stacking mechanisms
    • Authors: Yanbin Zhang; Changhe Li; Heju Ji; Xiaohui Yang; Min Yang; Dongzhou Jia; Xianpeng Zhang; Runze Li; Jun Wang
      Abstract: Publication date: Available online 13 June 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yanbin Zhang, Changhe Li, Heju Ji, Xiaohui Yang, Min Yang, Dongzhou Jia, Xianpeng Zhang, Runze Li, Jun Wang
      Numerous researchers have developed theoretical and experimental approaches to force prediction in surface grinding under dry conditions. Nevertheless, the combined effect of material removal and plastic stacking on grinding force model has not been investigated. In addition, predominant lubricating conditions, such as flood, minimum quantity lubrication, and nanofluid minimum quantity lubrication, have not been considered in existing force models. This work presents an improved theoretical force model that considers material-removal and plastic-stacking mechanisms. Grain states, including cutting and ploughing, are determined by cutting efficiency (β). The influence of lubricating conditions is also considered in the proposed force model. Simulation is performed to obtain the cutting depth (a g) of each “dynamic active grain.” Parameter β is introduced to represent the plastic-stacking rate and determine the force algorithms of each grain. The aggregate force is derived through the synthesis of each single-grain force. Finally, pilot experiments are conducted to test the theoretical model. Findings show that the model's predictions are consistent with the experimental results, with average errors of 4.19% and 4.31% for the normal and tangential force components, respectively.

      PubDate: 2017-06-15T13:23:09Z
      DOI: 10.1016/j.ijmachtools.2017.06.002
       
  • Maximum undeformed equivalent chip thickness for ductile-brittle
           transition of zirconia ceramics under different lubrication conditions
    • Authors: Min Yang; Changhe Li; Yanbin Zhang; Dongzhou Jia; Xianpeng Zhang; Yali Hou; Runze Li; Jun Wang
      Abstract: Publication date: Available online 13 June 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Min Yang, Changhe Li, Yanbin Zhang, Dongzhou Jia, Xianpeng Zhang, Yali Hou, Runze Li, Jun Wang
      This study investigates the critical maximum undeformed equivalent chip thickness for ductile-brittle transition (DBh max-e ) of zirconia ceramics under different lubrication conditions. A DBh max-e model is developed through geometry and kinematics analyses of ductile-mode grinding. Result shows that DBh max-e decreases with increasing friction coefficient (μ). An experimental investigation is then conducted to validate the model and determine the effect of dry lubrication, minimum quantity lubrication (MQL), and nanoparticle jet minimum quantity lubrication (NJMQL) conditions on DBh max-e . According to different formation mechanisms of debris, the grinding behavior of zirconia ceramics is categorized into elastic sliding friction, plastic removal, powder removal, and brittle removal. Grinding forces per unit undeformed chip thickness (F n/h and F t/h ) are obtained. The lubrication condition affects the normal force and ultimately influences the resultant force on workpiece. In comparison with dry grinding (DBh max-e  = 0.8 μm), MQL and NJMQL grinding processes increase DBh max-e by 0.99 and 1.79 μm respectively; this finding is similar to model result. The theoretical model is then assessed by different volume fractions of nanofluids under NJMQL condition with an average percentage error of less than 8.6%.

      PubDate: 2017-06-15T13:23:09Z
      DOI: 10.1016/j.ijmachtools.2017.06.003
       
  • Formation of uniform metal traces using alternate droplet printing
    • Authors: Jun Luo; Wenqiang Wang; Wei Xiong; He Shen; Lehua Qi
      Abstract: Publication date: Available online 10 June 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jun Luo, Wenqiang Wang, Wei Xiong, He Shen, Lehua Qi
      Formation of uniform traces is fundamental, but challenging, in droplet-based 3D printing. Due to the scalloped surface topography of metal droplets and complex thermal deformation between them, sequentially printed traces tend to form low-quality shapes. Here, an alternate droplet printing method is proposed to print uniform metal traces. Instead of printing droplets successively, discrete droplet array with uniform intervals was first printed. Then, the gaps between droplets were fully filled up in a later printing iteration. Herein, the proper combination of the step interval and the thermal state in the droplet printing process were first investigated to ensure the success of the proposed printing method. Four typical shapes of segments were identified using multiple three-droplet deposition experiments. Moreover, metal trace printing experiments further revealed five distinct trace topographies. In addition, the relationship between the topographies of printed traces and the printing parameters (i.e., temperature of the substrate and printing step size) was studied to establish a trace-shape map. Finally, experiments show that metal traces with the dimensionless roughness (Ra/D d ) of 1.8% were successfully printed. The results demonstrate a significant reduction of the roughness comparing to the literature results printed in consecutive sequence.

      PubDate: 2017-06-11T07:22:58Z
      DOI: 10.1016/j.ijmachtools.2017.05.004
       
  • Virtual pivot alignment method and its influence to profile error in
           bonnet polishing
    • Authors: Junkang Guo; Anthony Beaucamp; Soichi Ibaraki
      Abstract: Publication date: Available online 6 June 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Junkang Guo, Anthony Beaucamp, Soichi Ibaraki
      This paper proposes a measurement and adjustment procedure for virtual pivot errors using the R-test and investigates the influence of virtual pivot errors to the surface profile in bonnet polishing. Initially, kinematic modeling is carried out for describing the location errors of rotary axes and defining overall errors of the virtual pivot arm. Then, the R-test is introduced to measure the three-dimensional displacement of a sphere located at the virtual pivot point and identify location errors. The adjustment procedure for virtual pivot errors is developed by means of mathematical analysis. The measurement and adjustment approach is applied to an ultra-precision polishing machine, on which an adjustment experiment was conducted to validate the proposed method. Based on this, a contrastive polishing experiment on a concave lens is carried out under good and poor virtual pivot errors. The experiment result shows that the maximum form deviation of the polished surface profile is reduced from 241.0 nm to 89.6 nm when good alignment of virtual error is achieved. Analytical simulation based on a material removal model of the bonnet polishing tool and machine is implemented to reveal the influence of virtual pivot errors to polishing quality.

      PubDate: 2017-06-11T07:22:58Z
      DOI: 10.1016/j.ijmachtools.2017.06.001
       
  • Energy distribution modulation by mechanical design for electrochemical
           jet processing techniques
    • Authors: Jonathon Mitchell-Smith; Alistair Speidel; Jennifer Gaskell; Adam T. Clare
      Abstract: Publication date: Available online 31 May 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jonathon Mitchell-Smith, Alistair Speidel, Jennifer Gaskell, Adam T. Clare
      The increasing demand for optimised component surfaces with enhanced chemical and geometric complexity is a key driver in the manufacturing technology required for advanced surface production. Current methodologies cannot create complex surfaces in an efficient and scalable manner in robust engineering materials. Hence, there is a need for advanced manufacturing technologies which overcome this. Current technologies are limited by resolution, geometric flexibility and mode of energy delivery. By addressing the fundamental limitations of electrochemical jetting techniques through modulation of the current density distribution by mechanical design, significant improvements to the electrochemical jet process methods are presented. A simplified 2D stochastic model was developed with the ability to vary current density distribution to assess the effects of nozzle-tip shape changes. The simulation demonstrated that the resultant profile was found to be variable from that of a standard nozzle. These nozzle-tip modifications were then experimentally tested finding a high degree of variance was possible in the machined profile. Improvements such as an increase in side-wall steepness of 162% are achieved over a standard profile, flat bases to the cut profile and a reduction of profile to surface inter-section radius enable the process to be analogous to traditional milling profiles. Since electrode design can be rapidly modified EJP is shown to be a flexible process capable of varied and complex meso-scale profile creation. Innovations presented here in the modulation of resistance in-jet have enabled electrochemical jet processes to become a viable, top-down, single-step method for applying complex surfaces geometries unachievable by other means.
      Graphical abstract image

      PubDate: 2017-06-01T13:16:43Z
      DOI: 10.1016/j.ijmachtools.2017.05.005
       
  • Prediction of surface roughness in abrasive waterjet trimming of fiber
           reinforced polymer composites
    • Authors: J. Schwartzentruber; J.K. Spelt; M. Papini
      Abstract: Publication date: Available online 25 May 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): J. Schwartzentruber, J.K. Spelt, M. Papini
      Surface roughness is a valuable metric when assessing abrasive waterjet machining (AWJM) cut quality. This paper presents 2D and 3D models capable of predicting the surface roughness during abrasive waterjet (AWJ) trimming of composite substrates. The composites used were a carbon-fiber laminate with an epoxy resin and a random oriented carbon-fiber/vinyl ester. The models were based on an earlier rigid-plastic erosive particle indentation model capable of predicting crater sizes using the particle impact and substrate properties. In the 2D model, single particle impact craters were aligned to form multi-particle impact profiles that were iteratively superimposed until a steady-state surface roughness was achieved. The 3D model generated conical craters that were individually superimposed until a steady-state surface roughness was achieved. The models were capable of predicting the surface roughness with an average error of 10% and 16%, for the 2D and 3D models, respectively. The models show that the surface roughness decreased with an increase in particle velocity, a decrease in kerf taper, and an increase in the dynamic hardness of the target.

      PubDate: 2017-05-27T08:40:38Z
      DOI: 10.1016/j.ijmachtools.2017.05.007
       
 
 
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