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  Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 308 journals)
    - CERAMICS, GLASS AND POTTERY (27 journals)
    - MACHINERY (35 journals)
    - MANUFACTURING AND TECHNOLOGY (184 journals)
    - METROLOGY AND STANDARDIZATION (4 journals)
    - PACKAGING (16 journals)
    - PAINTS AND PROTECTIVE COATINGS (5 journals)
    - PLASTICS (35 journals)
    - RUBBER (2 journals)

MACHINERY (35 journals)

Showing 1 - 35 of 35 Journals sorted alphabetically
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9)
Advanced Energy Materials     Hybrid Journal   (Followers: 26)
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 Manufacturing and Materials Processing     Open Access  
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: 146)
Machine Learning and Knowledge Extraction     Open Access  
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  [3120 journals]
  • Optimisation of process parameters to address fundamental challenges
           during selective laser melting of Ti-6Al-4V: A review
    • Authors: H. Shipley; D. McDonnell; M. Culleton; R. Coull; R. Lupoi; G. O'Donnell; D. Trimble
      Pages: 1 - 20
      Abstract: Publication date: May 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 128
      Author(s): H. Shipley, D. McDonnell, M. Culleton, R. Coull, R. Lupoi, G. O'Donnell, D. Trimble
      Selective Laser Melting (SLM) is an additive manufacturing (AM) technique which has been heavily investigated for the processing of Ti-6Al-4V (Ti64) which is used in the biomedical, aerospace and other industries. To date the SLM processing of this material has been inhibited by the requirement of post processes due to three primary challenges of martensitic microstructures, undesired porosity and residual stresses which are present in the as-built state. This work identifies the state of the art in process optimisation which is being used to confront these challenges in the as-built state with a view to removing the reliance on post processing. Regarding process optimisation, maximising part density is the primary goal due to the negative influence of pores on fracture and fatigue properties. To accomplish this, a high energy input is required which results in high cooling rates during processing. It is these cooling rates which are instrumental in the microstructural evolution and residual stress production. Accordingly novel methods have been proposed which aim to maintain the necessary high level of energy input but control the cooling rates to tailor the microstructure and reduce residual stresses. Research gaps have been identified pertaining to all three of these challenges when considering mechanical properties of as-built components. Thus in its current state post processes remain critical, however promising techniques in early stage development provide encouragement going forward.

      PubDate: 2018-02-05T09:34:10Z
      DOI: 10.1016/j.ijmachtools.2018.01.003
      Issue No: Vol. 128 (2018)
       
  • A review on process capabilities of electrochemical micromachining and its
           hybrid variants
    • Authors: Krishna Kumar Saxena; Jun Qian; Dominiek Reynaerts
      Pages: 28 - 56
      Abstract: Publication date: April 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 127
      Author(s): Krishna Kumar Saxena, Jun Qian, Dominiek Reynaerts
      Electrochemical micromachining (micro-ECM) is an unconventional micromachining technology that has capability to fabricate high aspect ratio micro-holes, micro-cavities, micro-channels and grooves on conductive and difficult-to-cut materials. Both academia and industry have the consensus that it offers promising machining performance especially in terms of high surface finish, no tool wear and absence of thermally induced defects. Furthermore in order to machine novel materials with extreme properties, novel hybrid electrochemical micromachining technologies are under development. With these hybrid micro-ECM technologies, capabilities of micro-ECM can be expanded by combining it with other processes. To fully exploit the potential as well as improve micro-ECM technology and related hybrid processes, a wide spectrum of multidisciplinary knowledge is needed. The present review systematically discusses process capabilities and research developments of electrochemical micromachining and its hybrid variants considering knowledge of both basic and applied research fields. After few introductory review articles in prior state of the art, this review fills an important gap in research literature by presenting first time an extended literature source with a wide coverage of recent research developments in electrochemical micromachining technology and its hybrid variants. This paper outlines the research and engineering developments in electrochemical micromachining technology and its hybrid variants, review of the related concepts, aspects of tooling, advanced process capabilities and process energy sources. It also provides new sights into technological understanding of micro-ECM technology which will be helpful in future engineering developments of this technology.

      PubDate: 2018-02-05T09:34:10Z
      DOI: 10.1016/j.ijmachtools.2018.01.004
      Issue No: Vol. 127 (2018)
       
  • Surface form error prediction in five-axis flank milling of thin-walled
           parts
    • Authors: Zhou-Long Li; Oguzhan Tuysuz; Li-Min Zhu; Yusuf Altintas
      Abstract: Publication date: Available online 3 February 2018
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Zhou-Long Li, Oguzhan Tuysuz, Li-Min Zhu, Yusuf Altintas
      The dimensional tolerance of flexible, thin-walled aerospace parts can be violated by the excessive static deflections during milling. This paper proposes a method to predict the dimensional surface form errors caused by the deflections of both flexible workpiece and the cutter in five-axis flank milling of thin-walled parts. The end-mill is modeled as a cantilevered beam. The stiffness of the thin-walled part varies as the metal is removed and the tool-part contact location changes. The time varying stiffness of the thin-walled part is predicted by an efficient structural stiffness modification method that only needs the FE model of the initial workpiece and avoids re-meshing the part at each cutter location. The cutting forces are distributed over both the tool and the part in the engagement zone, and the effect of deflections on the immersion is calculated. The effect of radial runout of the tool is considered in chip thickness, hence in the cutting force prediction. Finally, the cutter and the workpiece deflections are considered to predict the surface errors left on the finished part. The proposed method has been proven in five-axis blade milling experiments.

      PubDate: 2018-02-05T09:34:10Z
      DOI: 10.1016/j.ijmachtools.2018.01.005
       
  • Accurate three-dimensional contouring error estimation and compensation
           scheme with zero-phase filter
    • Authors: Chuxiong Hu; Ze Wang; Yu Zhu; Ming Zhang
      Abstract: Publication date: Available online 31 January 2018
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Chuxiong Hu, Ze Wang, Yu Zhu, Ming Zhang
      Contour following is an important research topic for multi-axis CNC systems. In this paper, to simultaneously meet the challenges of accurate contouring error estimation and high-performance contouring control, which are very significant for three-dimensional contouring following tasks, a numerical calculation based contouring error estimation and contour compensation scheme is proposed. Unlike any existing geometric approximation methods, the proposed scheme calculates the contouring error through a numerical calculation algorithm. Specifically, a cost function is defined as the spatial distance between the actual point and the point located on the reference contour. When the minimum value of the cost function is obtained through the numerical calculation, accurate contouring error vector can be obtained even under extreme contouring tasks with high-speed, large-curvature and sharp-corner. Then the calculated contouring error is projected to each axis. After a zero-phase filter with low-pass characteristic, the axial contouring error is fed back to the corresponding axis as a kind of contour compensation. The added filter can effectively suppress the high-frequency noise widely existing in contour error signal. Moreover, our proposed contour compensation scheme can be realized iteratively for further improvement of contouring performance. Various comparative experiments are performed to verify the effectiveness of the proposed contouring error estimation and compensation scheme. The results demonstrate that in comparison with traditional position loop CCC method, the proposed scheme can achieve not only nearly perfect contouring error estimation but also obvious promotion of contouring accuracy.

      PubDate: 2018-02-05T09:34:10Z
      DOI: 10.1016/j.ijmachtools.2018.01.001
       
  • Modeling and simulation of the distribution of undeformed chip thicknesses
           in surface grinding
    • Authors: Yuzhou Zhang; Congfu Fang; Guoqin Huang; Xipeng Xu
      Abstract: Publication date: Available online 31 January 2018
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yuzhou Zhang, Congfu Fang, Guoqin Huang, Xipeng Xu
      The distribution of undeformed chip thicknesses is the kinematic “copy” of grain space distribution on a workpiece and has an important influence on the grinding results. In this study, a wheel topography model is developed that can be integrated with a workpiece model, a kinematic model and a calculation model of undeformed chip thickness of a single grain to obtain the distribution of undeformed chip thicknesses. In order to verify the integrated model, a single-layer brazed diamond grinding wheel is fabricated, and the topography measurements of the grinding wheel are conducted. The measured data are used in the integrated model to perform a simulation; the simulation results are consistent with the test results. At the same time, the model is verified with grains that are uniformly distributed. Then, simulations utilizing the integrated model are used to thoroughly study the grinding process. The distribution of grain protrusion height can be controlled by radial numerical dressings on the grinding wheel. Thus, the role of the distribution of grain protrusion height on the undeformed chip thickness distribution can be quantified by using radial numerical dressings on the grinding wheel. Additionally, the relationship between the average value of the distribution of undeformed chip thicknesses, h mean , and the surface roughness can be determined by simulation. It is shown that the surface roughness can be controlled quantitatively by radial numerical dressings on the wheel.

      PubDate: 2018-02-05T09:34:10Z
      DOI: 10.1016/j.ijmachtools.2018.01.002
       
  • Singularity avoidance for five-axis machine tools through introducing
           geometrical constraints
    • Authors: Min Wan; Yang Liu; Wan-Jing Xing; Wei-Hong Zhang
      Abstract: Publication date: Available online 3 January 2018
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Min Wan, Yang Liu, Wan-Jing Xing, Wei-Hong Zhang
      Singularities in five-axis machining are a series of deadly positions, which may cause unstable axis movements and deteriorate the performance of machine tools. This paper presents an optimization strategy to locally deform the tool path so that singularities of five-axis machine tools can be avoided. To achieve this purpose, a new concept of “forbidden circle”, which is the projection of the three dimensional “singular cone” associated with tool orientations in a two dimensional space named P-plane, is established for the first time to transform the complicated three dimensional problem into a two dimensional problem. Based on this idea, the projected points in P-plane are interpolated as B-spline first, and then, the B-spline control points are locally optimized by taking the “forbidden circle” as the geometrical constraint to keep the B-spline from crossing it. Especially, in the optimization procedure, the constraints are linearized with the changes of B-spline control points to change the whole optimization problem as a typical positive definite quadratic programming problem, which can achieve one and only global optimal solution. By doing so, singularity is avoided, and at the same time, the machining errors caused by tool path deformation can be minimized. Simulation and experimental results verify the effectiveness of the singularity avoidance method.

      PubDate: 2018-02-05T09:34:10Z
      DOI: 10.1016/j.ijmachtools.2017.12.006
       
  • Feasibility studies of a novel extrusion process for curved profiles:
           Experimentation and modelling
    • Authors: Wenbin Zhou; Jianguo Lin; Trevor A. Dean; Liliang Wang
      Pages: 2304 - 2309
      Abstract: Publication date: Available online 5 December 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Wenbin Zhou, Jianguo Lin, Trevor A. Dean, Liliang Wang
      The work described in this paper concerns a novel method for directly forming curved profiles/sections from billets in one extrusion operation using two opposing punches. Its mechanics are based on internal differential material flow, and it has been given the acronym, differential velocity sideways extrusion (DVSE). A tool set enabling sideways extrusion to be performed using opposing punches moving with different velocities was used for a series of experiments in which punch velocity ratio and extrusion ratio were process parameters. Plasticine was used as a model work-piece material and a series of compression tests were undertaken, to determine its constitutive properties and gain an estimate of work-piece die friction for use in process simulation. Curvature of extrudate can be controlled and varied using a difference between the velocities of the two punches, defined by velocity ratio. Greater curvature is achieved with lower velocity ratio. Curvature is also dependent on extrusion ratio, an increase in which increases curvature, although curvature is less sensitive to it than to velocity ratio. The extent of work-piece flow velocity gradient across the die exit orifice, which causes curvature, has been identified. Severe plastic deformation of the extrudate occurs in a way similar to channel angular extrusion (CAE), thus a greatly promoted effective strain level is achieved, though it is not always uniform across a section. The inner bending region of an extrudate experiences maximum localised effective strain, which decreases with decrease in curvature. To the authors' knowledge this is the first publication in which extrudate curvature is deliberately induced using opposing punches with differential velocities. Although only fixed velocity ratio values have been used in the work described in this paper the ability to change during operation exists and the process has the potential for the production of a profile with different curvature along its length.
      Graphical abstract image

      PubDate: 2017-12-13T01:53:56Z
      DOI: 10.1016/j.proeng.2017.10.999
      Issue No: Vol. 207 (2017)
       
  • The influence of scan length on fabricating thin-walled components in
           selective laser melting
    • Authors: Zhonghua Li; Renjun Xu; Zhengwen Zhang; Ibrahim Kucukkoc
      Pages: 1 - 12
      Abstract: Publication date: March 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 126
      Author(s): Zhonghua Li, Renjun Xu, Zhengwen Zhang, Ibrahim Kucukkoc
      As one of the advanced additive manufacturing (AM) processes, the selective laser melting (SLM) process provides the possibility of manufacturing almost any complex parts in a wide range of metal materials. In the SLM process, undesired distortion and shrinkage are much more likely to occur in forming Ti6Al4V thin-walled parts due to high-temperature gradients and thermal stresses. In this study, a three-dimensional (3D) finite element model based on indirect coupled thermal-structural analysis is applied to study the variations of temperature, stress and strain fields with different scan lengths. At the same time, the corresponding validation experiments were conducted. It was found that the scan length chiefly affects the second peak temperature rather than the highest temperature. The strain is majorly decided by stress generated during the SLM process. The deviations of thin-walled parts are approximately proportional to the scan lengths. The most suitable scan length is between 4 mm and 6 mm for thin-walled components with specified process parameters, in which case the shrinkage per unit is close to zero.

      PubDate: 2017-12-13T01:53:56Z
      DOI: 10.1016/j.ijmachtools.2017.11.012
      Issue No: Vol. 126 (2017)
       
  • Influence of geometric errors of guide rails and table on motion errors of
           hydrostatic guideways under quasi-static condition
    • Authors: Penghai Zhang; Yaolong Chen; Chengyong Zhang; Jun Zha; Tao Wang
      Pages: 55 - 67
      Abstract: Publication date: February 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 125
      Author(s): Penghai Zhang, Yaolong Chen, Chengyong Zhang, Jun Zha, Tao Wang
      Motion errors of hydrostatic guideways are mainly influenced by the geometric errors of guide rails and table which can be decomposed into harmonic waves of different frequencies based on Fourier transform. In this paper, a new approximate model is established to study the influence of geometric errors of guide rails and table on the motion errors of hydrostatic guideways using the equivalent third power of oil film thickness. It is found that, the motion errors are mainly affected by the geometric errors of guide rails rather than the geometric errors of table. The harmonic waves with wave numbers 0.5, 1.5, 2.5, 3.5, …, on the guide rails have no influence on the center displacement of table, and the harmonic waves with wave numbers 1, 2, 3, 4, …, have no influence on the yaw angle of table. The increment of land width and decrement of distance of two adjacent pads will result in enhancement of comprehensive averaging effect in consideration of center displacement and yaw angle. The approximate formulas have sufficient calculation accuracy compared with FEM when the ratio between amplitude of harmonic wave and initial film thickness is small. Using a deformed guide rail with wave numbers 0.5 and 1, the results of experiments agree well with the results calculated by approximate formulas and FEM. In the experiments, a novel method is proposed to manufacture the single harmonic wave of guide rail in the scale of micron meters, through which the amplitude and wavelength of the harmonic wave on guide rail can be controlled.

      PubDate: 2017-12-13T01:53:56Z
      DOI: 10.1016/j.ijmachtools.2017.10.006
      Issue No: Vol. 125 (2017)
       
  • Effect of apex offset inconsistency on hole straightness deviation in deep
           hole gun drilling of Inconel 718
    • Authors: Xinquan Zhang; Guan Leong Tnay; Kui Liu; A. Senthil Kumar
      Pages: 123 - 132
      Abstract: Publication date: February 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 125
      Author(s): Xinquan Zhang, Guan Leong Tnay, Kui Liu, A. Senthil Kumar
      Hole straightness deviation is the critical performance indicator in deep hole gun drilling process, particularly in manufacturing of corrosion resistant alloys like Inconel 718 with high yield strength. Poor understanding on the root causes of straightness deviation and difficulty to reduce it has dramatically increased the complexity and the manufacturing cost of this manufacturing process. Due to the fast tool wear in machining of Inconel, gun drills have to be changed frequently after a very short drilling distance. However, it has been found that the gun drill tool geometry cannot be precisely controlled, as there is a lack of appropriate gun drill regrinding and measurement system. In this study, a customized gun drill regrinding system integrated with an in-situ gun drill measurement system is designed and developed to obtain high-quality gun drills with precisely controlled tool geometry. The effect of apex offset variation on the hole straightness deviation is studied through 12 unsupported gun drilling experiments at thin-wall positions of an Inconel 718 workpiece with 160 ksi yield strength. 4 types of apex offset variation conditions (consistent, reciprocating, decreasing and increasing) with 3 times of repetition tests are conducted, and the measurement results have shown that consistent apex offset leads to the smallest hole straightness deviation among all the conditions. Through a series of FEM analysis and further measurement of internal cylindricity of machined holes, it has been concluded that unbalanced cutting force components applied on the previous gun drilled hole due to the inconsistent apex offset will cause the new formed hole to be deviated toward thin wall, due to the relatively larger material deformation at the thin-wall side than at the thick-wall side.

      PubDate: 2017-12-13T01:53:56Z
      DOI: 10.1016/j.ijmachtools.2017.11.011
      Issue No: Vol. 125 (2017)
       
  • A real-time interpolator for parametric curves
    • Authors: Wenbin Zhong; Xichun Luo; Wenlong Chang; Fei Ding; Yukui Cai
      Pages: 133 - 145
      Abstract: Publication date: February 2018
      Source:International Journal of Machine Tools and Manufacture, Volume 125
      Author(s): Wenbin Zhong, Xichun Luo, Wenlong Chang, Fei Ding, Yukui Cai
      Driven by the ever increasing need for the high-speed high-accuracy machining of freeform surfaces, the interpolators for parametric curves become highly desirable, as they can eliminate the feedrate and acceleration fluctuation due to the discontinuity in the first derivatives along the linear tool path. The interpolation for parametric curves is essentially an optimization problem, and it is extremely difficult to get the time-optimal solution. This paper presents a novel real-time interpolator for parametric curves (RTIPC), which provides a near time-optimal solution. It limits the machine dynamics (axial velocities, axial accelerations and jerk) and contour error through feedrate lookahead and acceleration lookahead operations, meanwhile, the feedrate is maintained as high as possible with minimum fluctuation. The lookahead length is dynamically adjusted to minimize the computation load. And the numerical integration error is considered during the lookahead calculation. Two typical parametric curves are selected for both numerical simulation and experimental validation, a cubic phase plate freeform surface is also machined. The numerical simulation is performed using the software (open access information is in the Acknowledgment section) that implements the proposed RTIPC, the results demonstrate the effectiveness of the RTIPC. The real-time performance of the RTIPC is tested on the in-house developed controller, which shows satisfactory efficiency. Finally, machining trials are carried out in comparison with the industrial standard linear interpolator and the state-of-the-art Position-Velocity-Time (PVT) interpolator, the results show the significant advantages of the RTIPC in coding, productivity and motion smoothness.

      PubDate: 2017-12-13T01:53:56Z
      DOI: 10.1016/j.ijmachtools.2017.11.010
      Issue No: Vol. 125 (2017)
       
  • 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)
       
  • Tensile stresses in fine blanking tools and their relevance to tool
           fracture behaviour
    • Authors: Krobath Ecker; Deller Leitner Marsoner
      Abstract: Publication date: Available online 21 December 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): M. Krobath, T. Klünsner, W. Ecker, M. Deller, N. Leitner, S. Marsoner
      In order to enhance the productivity of the fine blanking process there is a tendency to apply high strength tool materials with superior resistance to wear and plastic deformation such as WC-Co hard metals. Due to the mean stress sensitivity of these high strength materials under fatigue loading conditions, there is a need to describe the tool load situation including previously unconsidered tensile tool load components and mean stress. To this end a finite element-based tool load analysis was performed that describes the cutting process and the tool's retraction from the remaining sheet material. The tool load was revealed to contain significant tensile components that occur during tool retraction. Their location on the lateral punch surface coincides with origins of tool fracture in two thirds of investigated fine blanking punches that failed close to the cutting edge in an industrial production scale fine blanking environment. The influence of friction between punch and sheet on the magnitude of the cyclic stress range and mean stress that act locally at the tool surface was investigated. As one of the main results, a first approximation for a surface quality requirement for fine blanking tools made of WC-Co hard metal was quantitatively estimated as a function of the friction coefficient based on linear elastic fracture mechanics.

      PubDate: 2017-12-27T01:03:10Z
       
  • Editorial
    • Authors: Trevor A. Dean
      Abstract: Publication date: Available online 16 December 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Trevor A. Dean


      PubDate: 2017-12-27T01:03:10Z
      DOI: 10.1016/j.ijmachtools.2017.12.004
       
  • A new receptance coupling substructure analysis methodology to predict
           tool tip dynamics
    • Authors: Yulei Qingzhen; Shaokun Zhang Yuhan Wang
      Abstract: Publication date: Available online 7 December 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yulei Ji, Qingzhen Bi, Shaokun Zhang, Yuhan Wang
      Tool tip frequency response function (FRF) is essential for chatter stability diagram in machining. But new modal tests are required for different tool-holder-spindle assemblies. To avoid these tests, receptance coupling substructure analysis (RCSA) method has been developed. Previous research proved that the full receptance matrix, which contains rotational and moment contributes, influences the RCSA accuracy. By improving the accuracy and efficiency in acquiring the full receptance matrix, this paper presents a new RCSA methodology to predict the tool tip dynamics when a new tool is selected. To identify the contact dynamics between the tool and tool holder, one required receptance matrix is experimentally measured with a reference tool attached on the machine. Comparing to the classical RCSA technique, an enhanced approach is proposed to better estimate the receptance matrix. Only one impact positon is required in the experiment. The enhanced approach introduces two compensation strategies to process the measuring data from impact test. Each compensation strategy can be chosen to improve the estimation accuracy. The measured receptances, together with the finite element models of the reference tool and the new tool, are used to predict the unknown tool tip FRF. Both numerical simulation and practical experiment are conducted to validate the proposed methodology. The results show that the proposed method is preferred when multiple modes should be considered.

      PubDate: 2017-12-13T01:53:56Z
       
  • Effect of tool wear evolution on chip formation during dry machining of
           Ti-6Al-4V alloy
    • Authors: Matthew Dargusch; Shoujin Sun Won Kim Tong Patrick Trimby Julie
      Abstract: Publication date: Available online 7 December 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Matthew S. Dargusch, Shoujin Sun, Ji Won Kim, Tong Li, Patrick Trimby, Julie Cairney
      The complex microstructure of segmented chips and the changing deformation mechanisms during the machining of the Ti-6Al-4V alloy for a given cutting tool have been explored. Chip geometry and microstructure were investigated for increasing volumes of material removed at a cutting speed at which the tool characteristically develops gradual flank wear. The degree of chip segmentation and deformation mode changed significantly as machining progressed from using a new tool towards a worn tool. Chip formation processes when machining near the end of the cutting tool life is characterised by increasing amounts of twinning formed through both tension and compression.
      Graphical abstract image

      PubDate: 2017-12-13T01:53:56Z
       
  • An insight into neutral layer shifting in tube bending
    • Authors: H. Li; J. Ma; B.Y. Liu; R.J. Gu; G.J. Li
      Abstract: Publication date: Available online 22 November 2017
      Source:International Journal of Machine Tools and Manufacture
      Author(s): H. Li, J. Ma, B.Y. Liu, R.J. Gu, G.J. Li
      Neutral layer shifting (NLS) is the most fundamental phenomenon during tube bending, which characterizes tension-compression (T-C) non-uniform bending deformation and directly affects multi-defect constrained formability and bending limits. However, the essentials of NLS in tube bending have not yet been clarified, viz., why does the neutral layer (NL) generally shift inward, can the NL shift outward possibly and even can be positively reconstructed' To address these issues, via analyzing the equilibrium conditions of moment and force during tube bending, an axial force equilibrium (AFE)-based hybrid analytical-numerical framework for NLS calculation is established and numerically implemented, in which the tubular materials properties such as the anisotropy/asymmetry behaviors, and the geometry parameters such as bending radius, tube diameters and wall thickness can be comprehensively considered. Taking rotary draw bending of Ti-3Al-2.5 V tube and press bending of AZ31 and A6063 tubes as the cases, the above NLS model is fully evaluated and validated. Using the above platform, the NLS rules related to the geometrical parameters and intrinsic material parameters are quantitatively identified, and within the above framework combined with the experiments, a thorough insight into the NLS upon tube bending is thus presented, viz., given geometrical parameters of bending, under combined action of the evolution of material properties and multi-tool induced additional forces, the inevitable transient T-C non-uniform deformation can be positively coordinated to satisfy the equilibrium of force, then the NLS can be reconstructed to propose innovative processes for improving bending formability.

      PubDate: 2017-12-13T01:53:56Z
      DOI: 10.1016/j.ijmachtools.2017.11.013
       
  • 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
       
  • 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
       
  • 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
       
 
 
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