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  Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 263 journals)
    - CERAMICS, GLASS AND POTTERY (25 journals)
    - MACHINERY (32 journals)
    - MANUFACTURING AND TECHNOLOGY (154 journals)
    - METROLOGY AND STANDARDIZATION (3 journals)
    - PACKAGING (14 journals)
    - PAINTS AND PROTECTIVE COATINGS (5 journals)
    - PAPER AND PULP (3 journals)
    - PLASTICS (25 journals)
    - RUBBER (2 journals)

MACHINERY (32 journals)

Acta Mechanica Solida Sinica     Full-text available via subscription   (9 followers)
Advanced Energy Materials     Hybrid Journal   (10 followers)
Applied Mechanics Reviews     Full-text available via subscription   (20 followers)
BER : Consumer Goods Industries Survey     Full-text available via subscription  
BER : Intermediate Goods Industries Survey     Full-text available via subscription   (1 follower)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (4 followers)
Electric Power Components and Systems     Hybrid Journal   (4 followers)
Engenharia AgrĂ­cola     Open Access  
Foundations and Trends® in Electronic Design Automation     Full-text available via subscription  
High Temperature Materials and Processes     Full-text available via subscription   (4 followers)
International Journal of Machine Tools and Manufacture     Hybrid Journal   (4 followers)
International Journal of Machining and Machinability of Materials     Hybrid Journal   (6 followers)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (10 followers)
International Journal of Precision Technology     Hybrid Journal  
International Journal of Rapid Manufacturing     Hybrid Journal   (4 followers)
International Journal of Rotating Machinery     Open Access   (1 follower)
ISRN Mechanical Engineering     Open Access   (5 followers)
Journal of Machinery Manufacture and Reliability     Hybrid Journal  
Journal of Machinery Manufacturing and Automation     Open Access   (2 followers)
Journal of Mechanics     Hybrid Journal   (16 followers)
Journal of Strain Analysis for Engineering Design     Hybrid Journal   (3 followers)
Journal of Terramechanics     Hybrid Journal   (1 follower)
Machine Design     Partially Free   (6 followers)
Machines     Open Access  
Materials     Open Access   (5 followers)
Mechanics Based Design of Structures and Machines: An International Journal     Hybrid Journal   (2 followers)
Micromachines     Open Access   (1 follower)
Practical Machinery Management for Process Plants     Full-text available via subscription  
Pump Industry Analyst     Full-text available via subscription  
Russian Engineering Research     Hybrid Journal  
Sensor Review     Hybrid Journal   (1 follower)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (4 followers)
International Journal of Machine Tools and Manufacture    [6 followers]  Follow    
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0890-6955
     Published by Elsevier Homepage  [2556 journals]   [SJR: 2.724]   [H-I: 71]
  • Receptance coupling for tool point dynamic prediction BY fixed boundaries
           approach
    • Abstract: Publication date: Available online 8 January 2014
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Iker Mancisidor , Aitor Urkiola , Rafael Barcena , Jokin Munoa , Zoltan Dombovari , Mikel Zatarain
      The material removal capability of machines is partially conditioned by self-excited vibrations, also known as chatter. In order to predict chatter free machining conditions, dynamic transfer function at the tool tip is required. In many applications, such as high-speed machining (HSM), the problematic modes are related to the flexibility of the tool, and experimental calculation of the Frequency Response Function (FRF) should be obtained considering every combination of tool, toolholder and machine. Therefore, it is a time consuming process which disturbs the production. The bibliography proposes the Receptance Coupling Substructure Analysis (RCSA) to reduce the amount of experimental tests. In this paper, a new approach based on the calculation of the fixed boundary dynamic behaviour of the tool is proposed. Hence, the number of theoretical modes that have to be considered is low, instead of the high number of modes required for the models presented up today. This way, the Timoshenko beam theory can be used to obtain a fast prediction. The accuracy of this new method has been verified experimentally for different tools, toolholders and machines.


      PubDate: 2014-01-11T15:46:57Z
       
  • Heating and material removal process in hybrid laser-waterjet ablation of
           silicon substrates
    • Abstract: Publication date: Available online 7 January 2014
      Source:International Journal of Machine Tools and Manufacture
      Author(s): V. Tangwarodomnukun , J. Wang , C.Z. Huang , H.T. Zhu
      A hybrid laser-waterjet micromachining technology has recently been developed for near damage-free micro-ablation. It uses a laser to heat and soften the target material and a waterjet to expel the laser-softened elemental material to decrease thermal damages and increase the material removal. A computational model for the hybrid laser-waterjet micro-grooving process for single crystalline silicon is presented in this paper using an enthalpy-based finite difference method. Laser heating and waterjet cooling and expelling with the temperature-dependent silicon properties are considered in the model to predict the temperature profiles of silicon and groove characteristics under different machining conditions. The simulation results show that the introduction of a high pressure waterjet enables to remove material at its soft-solid status much below its melting temperature, while the waterjet cooling effect can reduce the workpiece temperature during the laser non-pulse period and eliminate the effect of heat accumulation, so that the thermal damage induced by laser heating is minimized. The temperature field model is also used to predict the groove depth and profile, and it is found that the model can reasonably represent the machined groove characteristics when comparing to the experimental data.


      PubDate: 2014-01-11T15:46:57Z
       
  • IFC - Editorial board
    • Abstract: Publication date: February 2014
      Source:International Journal of Machine Tools and Manufacture, Volume 77




      PubDate: 2013-12-30T10:14:11Z
       
  • An Examination of the Fundamental Mechanics of Cutting Force Coefficients
    • Abstract: Publication date: Available online 21 December 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Minghai Wang , Lei Gao , Yaohui Zheng
      In metal cutting, the cutting force is the key factor affecting the machined surface, and is also important in determining reasonable cutting parameters. The research and construction of cutting force prediction models therefore has great practical value. The accuracy of cutting force prediction largely depends on the cutting force coefficients of the material. In the average cutting force model, cutting force coefficients are considered to be constant. This study makes use of experiments to investigate the cutting force coefficients in the average cutting force model, with a view to accurately identifying cutting force coefficients and verifying that they are related only to the tool-workpiece material couple and the tool geometrical parameters, and are not affected by milling parameters. To this end, the paper first examines the theory behind identifying cutting force coefficients in the average cutting force model. Based on this theory, a series of slot-milling experiments are performed to measure the milling forces, fixing spindle speeds and radial/axial depths of cutting, and linearly varying the feed per tooth. The tangential milling force coefficient and the radial milling force coefficient are then calculated by linearly fitting the experimental data. The obtained results show that altering the milling parameters does not change the milling force coefficients for the selected tool/workpiece material combination.
      Graphical abstract image

      PubDate: 2013-12-23T03:05:09Z
       
  • A novel spindle inclination error identification and compensation method
           in ultra-precision raster milling
    • Abstract: Publication date: Available online 21 December 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Guoqing Zhang , Suet To , Gaobo Xiao
      In the ultra-precision raster milling (UPRM) process, the existence of spindle inclination error can directly affect the dimensional accuracy of machined components. This study developed a novel spindle inclination error identification and compensation method based on the groove cutting in UPRM. In this method, the tilt angle of the intersection curve of two toruses (ICTT) generated from two neighboring rotary cuts in UPRM was measured to identify the spindle inclination error. A mathematical model was developed to simulate the ICTT profile and present the relationship between the tilt angle of ICTTs and the spindle inclination error by solving the differential of the ICTT function, by which the spindle inclination error can be solved under the given cutting parameters and the tilt angle of ICTTs. The effects of cutting parameters on the tilt angle of ICTTs were explored. An error compensation procedure was designed and a group of groove cutting experiments was conducted to identify and compensate the spindle inclination error. The theoretical and experimental results show that the proposed method can compensate for the spindle inclination error effectively and accurately.


      PubDate: 2013-12-23T03:05:09Z
       
  • Study on Surface Roughness Model and Surface Forming Mechanism of Ceramics
           in Quick Point Grinding
    • Abstract: Publication date: Available online 26 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Ma Lianjie , Gong Yadong , Liu Yueming , Chen Xiaohui
      The quick-point grinding experiment of fluorophlogopite was conducted by using a MK9025A profile grinder which considered the simple single factor, such as the grinding wheel and table feed speed, grinding depth, inclining angle and deflection angle. The experimental results indicated that the surface roughness was mainly influenced on inclining angle and deflecting angle. Moreover, the modified model of the quick-point grinding process was proposed in the paper, which based on Malkin kinematics model, Snoeys empirical model and grinding thickness empirical model. The inclining angle and deflecting angle was introduced in the modified model. Comparison of the predicted results of these models and experimental ones indicated that the modified model was in well agreement with the experimental data. Further, standard deviation of these models and experiment was studied in the paper, it is found that the modified model was the more ideal. In order to study the effect of various technology factors on the sensitivity of surface roughness, “Relative extremum error” concept was first proposed in the paper. It was found that simple single factor in the modified model were relatively sensitive to surface roughness than other models.


      PubDate: 2013-11-28T15:20:13Z
       
  • Study on the system matching of ultrasonic vibration assisted grinding for
           hard and brittle materials processing
    • Abstract: Publication date: Available online 22 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yan Wang , Bin Lin , Shaolei Wang , Xiaoyan Cao
      Ultrasonic vibration Assisted Grinding (UAG) is an effective processing method for hard and brittle materials. Compared with Common Grinding (CG), both of grinding force and workpiece surface quality is improved by UAG, but the principle of improvement is still unclear. In order to reveal the mechanism of grinding force reduction and grinding quality improvement in UAG, this paper presents a mathematical model for system matching in UAG of brittle materials. Assuming that brittle fracture is the primary mechanism of material removal in UAG of brittle materials, the system matching model is developed step by step. On the basis of this mathematical model, the mechanism of grinding force reduction and surface roughness forming are discussed. The advantage of UAG processing brittle materials is pointed out in theory. Using the model developed, influences of input variables on grinding force are predicted. These predicted influences are compared with those determined experimentally. This model can serve as a useful foundation for development of grinding force models in UAG of brittle materials and models to predict surface roughness in UAG.


      PubDate: 2013-11-24T14:39:45Z
       
  • A novel adaptive-feedrate interpolation method for NURBS tool path with
           drive constraints
    • Abstract: Publication date: Available online 23 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yuwen Sun , Yang Zhao , Yurong Bao , Dongming Guo
      Feedrate scheduling is crucial for CNC systems to generate a smooth movement which is able to satisfy increasing requirements on machining quality and efficiency. In this paper, a novel adaptive feedrate interpolation method is proposed for NURBS tool path with drive constraints. The tool path is first expressed in NURBS form, and then the satisfaction conditions of drive constraints are derived according to the kinematic and geometric characteristics of the NURBS tool path. On this base, a proportional adjustment algorithm, which can quantitatively reduce the accelerations and jerks of drive axes at the sensitive regions of feed profile, is proposed to achieve the new positions of violated sampling points. After each adjustment, a curve evolution strategy is used to ensure the feed profile is locally or globally deformed to the target positions with a good smoothness of path curve and the avoidance of re-interpolation. Through the iterative adjustment, a smooth feed profile with limited velocities, accelerations and jerks of drive axes is thus yielded along the entire tool path. Finally, performances of the proposed method are validated by performing both simulations and experiments on two freeform NURBS curves. The results show the effectiveness and reliability of the proposed feedrate interpolation method.


      PubDate: 2013-11-24T14:39:45Z
       
  • IFC - Editorial board
    • Abstract: Publication date: January 2014
      Source:International Journal of Machine Tools and Manufacture, Volume 76




      PubDate: 2013-11-21T03:00:35Z
       
  • Simulation model of debris and bubble movement in consecutive-pulse
           discharge of electrical discharge machining
    • Abstract: Publication date: Available online 11 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jin Wang , Fuzhu Han
      Debris concentration and bubble volume fraction in the bottom gap between the electrode and workpiece affects the state of consecutive-pulse discharge and the efficiency of electrical discharge machining (EDM). Thus, the mechanisms of debris and bubble movement during consecutive-pulse discharge should be elucidated. However, these mechanisms have not been fully understood because of debris and bubble movement in the machining gap is difficult to simulate and observe. This study proposes a three-dimensional model of flow field with liquid, gas, and solid phases for machining gap in EDM. The mechanisms of debris and bubble movement in the machining gap during consecutive-pulse discharge were analyzed through the model. Debris and bubble movement in consecutive-pulse discharge was observed through experiments. The results showed that the proposed simulation model is feasible. The bubble expansion is the main way that the bubbles exclude from machining gap. Much debris moves outside the machining gap following the excluded bubbles, which is the main way that the debris excludes from machining gap. The bubble expansion becomes strong with the increase of the discharge current and pulse-on time.
      Graphical abstract image

      PubDate: 2013-11-12T09:26:46Z
       
  • Further insight into the chip formation of ferritic-pearlitic steels:
           Microstructural evolutions and associated thermo-mechanical loadings
    • Abstract: Publication date: Available online 6 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): C. Courbon , T. Mabrouki , J. Rech , D. Mazuyer , F. Perrard , E. D'Eramo
      The main objective of this paper is to clarify the deformation mechanisms of ferritic-pearlitic steels in metal cutting and correlate them to the associated thermo-mechanical loadings. Dry orthogonal cutting tests have been performed on a normalized AISI 1045 steel with coated carbide tools. Experimental evidences of a drastic grain refinement process in the main deformation zones are advanced on the basis of optical microscope, field emission scanning electron microscope (FESEM) and Electron BackScaterred Diffraction (EBSD). Microstructural evolutions leading to a grain size down to 200nm and fragmented cementite are especially emphasised. A numerical approach is further employed to target and quantify the loadings applied to the machined material and extract further information on the Secondary Shear Zone (SSZ). Strains amplitude appears to be the driving parameter of these evolutions via a dynamic recrystallization process promoted by an intense and localised heat generation. The present contribution highlights that in-depth and micro scale investigations of chip formation including microstructural aspects are still required.


      PubDate: 2013-11-09T04:54:44Z
       
  • A Novel Approach to Machining Condition Monitoring of Deep Hole Boring
    • Abstract: Publication date: Available online 7 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Wenrong Xiao , Yanyang Zi , Binqiang Chen , Bing Li , Zhengjia He
      In the optimization of deep hole boring processes, machining condition monitoring (MCM) plays an important role for efficient tool change policies, product quality control and lower tool costs. This paper proposes a novel approach to the MCM of deep hole boring on the basis of the pseudo non-dyadic second generation wavelet transform (PNSGWT). This approach is developed via constructing a valuable indicator, i.e., the wavelet energy ratio around the natural frequency of boring bar. Self-excited vibration occurs at the frequency of the most dominant mode of the machine tool structure. Via modeling dynamic cutting process and performing its simulation analysis during deep hole boring, it is found that the vibration amplitudes in the nature frequency of the machine tool rise with the tool wear. The PNSGWT that has relative adjustable dyadic time-frequency partition grids, good time-frequency localizability and exact shift-invariance is used to extract the wavelet energy in the specified frequency band. Accordingly, the MCM of deep hole boring can be implemented by means of normalizing the wavelet energy. Finally, a field experiment on deep hole boring machine tool is conducted, and the result shows that the proposed method is effective in the process of monitoring tool wear and surface finish quality for deep hole boring.


      PubDate: 2013-11-09T04:54:44Z
       
  • On the mechanics of chip formation in Ti6Al4V turning with spindle speed
           variation
    • Abstract: Publication date: Available online 1 November 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Elio Chiappini , Stefano Tirelli , Paolo Albertelli , Matteo Strano , Michele Monno
      Titanium alloys are hard-to-cut materials and need to be machined at relatively low cutting speeds with obvious negative consequences on the profitability of machining. In order to enhance material removal rate (MRR), a strategy that relies on higher depths of cut could be chosen if vibrational issues due to regenerative chatter did not occur. A lot of research was done to suppress regenerative chatter without detrimental effects on productivity. One of the most interesting chatter suppression methods, mainly due to its flexibility and relative ease of implementation, is spindle speed variation (SSV), which consists in a continuous modulation of the nominal cutting speed. Sinusoidal spindle speed variation (SSSV) is a specific technique that exploits a sinusoidal law to modulate the cutting speed. The vast scientific literature on SSV was mainly focused on cutting process stability issues fully neglecting the study of the mechanics of chip formation in SSV machining. The aim of this work is to fill this gap: thus, finite element method (FEM) models of Ti6Al4V turning were setup to simulate both SSSV and constant speed machining (CSM). The models consider both the micro-geometry of the insert and the coating. Numerical results were experimentally validated on dry turning tests of titanium tubes exploiting the experimental assessment of cutting forces, cutting temperatures and chip morphology. Tool-chip contact pressure, tool engagement mechanism and the thermal distribution in the insert are some of the analysed numerical outputs because they cannot be easily assessed by experimental procedures. These quantities were useful to compare thermo-mechanical loads of the insert both in CSM and SSSV machining: it was observed that the loads significantly differ. Compared to CSM, the modulation of the cutting speed involves a higher tool-chip contact pressure peak, a higher maximum temperature and higher temperature gradients that could foster the main tool wear mechanisms.


      PubDate: 2013-11-04T20:05:20Z
       
  • Experimental Study of Surface Generation and Force Modeling in
           Micro-grinding of Single Crystal Silicon Considering Crystallographic
           Effects
    • Abstract: Publication date: Available online 30 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): J. Cheng , Y.D. Gong
      In this study, surface formation mechanism in micro-grinding of single crystal silicon is investigated based on analysis of undeformed chip thickness h m . A predicting model of grinding force considering crystallographic effects in micro-grinding of single crystal silicon is built. In this model, micro-grinding process of single crystal silicon is divided into two steps by one line on which h m of single grit equals to lattice constant. Two micro-grinding experiments with different ranges of cutting depths and feed rates have been designed and conducted on single crystal silicon to verify the model this paper proposes. The relationship between micro-grinding parameters and crack length l c is investigated and the empirical formula of l c is derived based on analysis of experiment results. Ductile-regime transitions in micro-grinding process of single crystal silicon have been revealed, 20nm and 100nm are turned out to be two critical conditions based on analysis of experiment results. It is found that the grinding force has a sudden change when micro-grinding process comes within material's crystal boundary in experiment. The force predicting model this paper proposes has well explained this phenomenon in micro-grinding of single cyrstal silicon. When micro-grinding undeformed chip thickness h m belows 0.5nm, micro grinding force doesn't decrease with the decrease of cutting parameters but has a rising tendency, and these experimental measurements also provide a support to the result of model this paper proposes.


      PubDate: 2013-11-01T03:06:00Z
       
  • Geometric Error Measurement and Identification for Rotary Table of
           Multi-axis Machine tool Using Double Ballbar
    • Abstract: Publication date: Available online 28 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jian-xiong Chen , Shu-wen Lin , Bing-wei He
      In this paper, comprehensive geometric errors, including linkage errors and volumetric errors, of a rotary table are measured totally by employing a double ballbar and obtained by a two-step identification procedure. The derivations of the center of the ball installed on the table are measured in the error sensitive directions with newly developed serial of two axes controlled circular paths. Hence, there are nine results measured from three mounting positions of the ball at the same rotation angle. These results are used to form the identification model based on the homogeneous transformation. Moreover, a sensitive analysis method is applied to select the optimum installation parameters of the ballbar to diminish the influence of the inaccuracy of the measurement parameters. As the mounting position errors of the socket on the table are inevitable during the installation of the balls, a new correction procedure is developed as well. Finally, an experiment is conducted on the four-axis machining center. The comparison results between the predicted errors and the measured results are shown to verify the proposed method.


      PubDate: 2013-11-01T03:06:00Z
       
  • Vibration-Assisted Dry Polishing of Fused Silica Using a Fixed-Abrasive
           Polisher
    • Abstract: Publication date: Available online 30 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Yaguo Li , Yongbo Wu , Libo Zhou , Masakazu Fujimoto
      Glass is a ubiquitous but essential material in everyday life and industry. The most common method for polishing glass is to use free abrasive techniques. However, this method is basically non-deterministic and lacks efficiency. Therefore, the vibration has been employed to aid fixed-abrasive polishing in our research. It is found that the vibration can increase the material removal rate while maintain surface quality in fixed abrasive polishing. Normalized Preston coefficients that are the index of the polishing capability of a certain polishing processes considerably increase in vibration-assisted polishing process. A mathematic model is set up to interpret the increase in material removal rate for vibration process. The modeled results show that the vibration can improve material removal by increasing vibration amplitude in vertical direction while the horizontal vibration contributes little to increasing material removal rate, which agrees well with experimental results. Aside from material removal, surface morphology of polished glass was also modeled for both vibration and conventional processes. Both experimented and simulated morphology evidence the effect of vibration that inscribes some periodic structure on polished surface. The possible mechanism in dry fixed abrasive polishing was also chemically analyzed and a probable mechanism is put forward to clarify the material removal in dry fixed abrasive polishing.


      PubDate: 2013-11-01T03:06:00Z
       
  • IFC - Editorial board
    • Abstract: Publication date: December 2013
      Source:International Journal of Machine Tools and Manufacture, Volume 75




      PubDate: 2013-10-24T03:30:30Z
       
  • Comparison of tool wear mechanisms and surface integrity for dry and wet
           micro drilling of nickel-base superalloys
    • Abstract: Publication date: Available online 22 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Muhammad Imran , Paul T. Mativenga , Ali Gholinia , Philip J. Withers
      The study focuses on the surface integrity and wear mechanisms associated with mechanical micro-drilling of nickel-base superalloy (Inconel 718) under dry and wet cutting conditions. Mechanical and metallurgical characterization was undertaken using scanning electron microscopy (SEM), backscatter electron microscopy (BSE), electron backscatter diffraction microscopy (EBSD), transmission electron microscopy (TEM), focused ion beam (FIB) microscopy, nanoindentation, energy dispersive spectroscopy (EDS) and elemental analysis techniques. The surface integrity results revealed large scale near surface deformations with high dislocation density along with nanocrystalline grain structures both under wet cutting conditions, with evidence of recrystallization and lower dislocation density for dry cutting. Cutting conditions play a significant role in determining the depth of the affected layer, the frequency of misorientations, the microstructures and the stored energy found there. The cutting temperature and use of coolant play a key role in the formation of the altered surfaces. Abrasion, diffusion and micro chipping were found to be the main wear mechanisms for wet cutting compared to abrasion, high adhesion, macro chipping and catastrophic failure for dry cutting. Adhesion of work-piece material to the tool associated with abrasion and diffusion processes is the main contributor to wear phenomena. The results are important in guiding the choice of cutting conditions for acceptable surface integrity.


      PubDate: 2013-10-24T03:30:30Z
       
  • Ductile Fracture and Free Surface Roughening Behaviors of Pure Copper
           Foils for Micro/Meso-scale Forming
    • Abstract: Publication date: Available online 16 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Tsuyoshi Furushima , Hitomi Tsunezaki , Ken-ichi Manabe , Sergei Alexsandrov
      To clarify the fracture mechanism of metal foils, the ductile fracture and the free surface roughening behaviors for pure copper foils are focused on in this study. Pure copper foils and sheets with various initial thicknesses of 0.05, 0.1, 0.3, and 0.5mm are used. Fracture strain decreases with decreasing thickness under the uniaxial tensile state. In particular, the fracture strain decreases dramatically from a thickness of 0.3mm to 0.1mm. Dimples cannot be observed on the fracture surface of metal foils with thicknesses of 0.05 and 0.1mm, whereas metal sheets with thicknesses of 0.3 and 0.5mm had some dimples on the fracture surface. Free surface roughening can be observed for metal foils as well as metal sheets. The rate of increase in the ratio of surface roughness to thickness dramatically increases from a thickness of 0.3mm to 0.1mm because of the decreasing number of grains in the thickness, which is inversely proportional to the rate of increase in the ratio of surface roughness to thickness. In particular, when the number of grains in the thickness becomes less than approximately 5, the rate of increase in the ratio of surface roughness to thickness significantly increases in inverse proportion, leading to low fracture strain. Additionally, the fracture strain and the number of dimples on the fracture surface decreases for a metal sheet with a simulated surface roughness prepared by machining, which has nearly the same ratio of surface roughness and pitch to thickness as those of metal foil. Furthermore, ductile fracture criteria could not be used to predict the fracture of metal foil in stretch forming. Referring to these results, we discuss the ductile fracture mechanism of metal foils. Firstly, the surface roughness of metal foils increases with plastic deformation owing to free surface roughening phenomenon. Secondly, the ratio of surface roughness to thickness increases with plastic deformation. At the concave region formed by free surface roughening, local deformation occurs. Thirdly, it can be considered that the local deformation caused by free surface roughening leads to fracture. On the basis of this mechanism of ductile fracture resulting from the free surface roughening of metal foils, the metal foils have low fracture strain compared with metal sheets.


      PubDate: 2013-10-16T03:29:40Z
       
  • IFC - Editorial board
    • Abstract: Publication date: November 2013
      Source:International Journal of Machine Tools and Manufacture, Volume 74




      PubDate: 2013-10-11T22:05:59Z
       
  • Experimental and Numerical Investigation on Micro Deep Drawing Process of
           Stainless Steel 304 Foil Using Flexible Tools
    • Abstract: Publication date: Available online 7 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Ihsan Irthiea , Graham Green , Safa Hashim , Abdulbast Kriama
      Flexible forming technology provides significant application potential in various areas of manufacturing, particularly at a miniaturized level. Simplicity, versatility of process and feasibility of prototyping makes forming techniques by using flexible tools suitable for micro sheet metal forming. This paper reports the results of FE simulation and experimental research on micro deep drawing processes of stainless steel 304 sheets utilising a flexible die. The study presents a novel technique in which an initial gap (positive or negative) is adopted between an adjustment ring and a blank holder employed in the developed forming system. The blank holder is moveable part and supported by a particular spring that provides the required holding force. The forming parameters (anisotropy of SS 304 material, initial gap, friction conditions at various contact interfaces and initial sheet thickness) related with the forming process are in details investigated. The FE models are built using the commercial code Abaqus/Standard. The numerical predictions reveal the capability of the proposed technique on producing micro metallic cups with high quality and large aspect ratio. To verify these results, number of micro deep drawing experiments is conducted using a special set up developed for this purpose. As providing a fundamental understanding is required for the commercial development of this novel forming technique, hence the optimization of the initial gap in accordance with each sheet thickness, thickness distribution and punch force/stroke relationship are detected.


      PubDate: 2013-10-11T22:05:59Z
       
  • Smooth feedrate planning for continuous short line tool path with contour
           error constraint
    • Abstract: Publication date: Available online 2 October 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jingchuan Dong , Taiyong Wang , Bo Li , Yanyu Ding
      In the machining program for free form surfaces, the tool path is usually represented as continuous short lines. For the computer numerical control, the feedrate profile for short line tool path should be smooth and optimized in order to achieve high machining quality and high speed. In high speed machining, the feedrate profile also has a strong influence on contour accuracy. This paper presents a new real-time smooth feedrate planning algorithm for short line tool path, in which the contour error constraint is included. To realize contour error control, the feedrate is adaptively adjusted based on the curvature radius of the tool path, which is directly estimated from the short lines. The 7-phase jerk-limited look-ahead planning is employed to generate a smooth feedrate profile. The target feedrate filter (TFF) and planning units merging techniques are developed to improve the smoothness of the feedrate profile and reduce the overhead on look-ahead. The advantage of the proposed algorithm is that, it is not only convenient to achieve the balance among accuracy, smoothness and productivity by adjusting parameters, but also efficient in design, which makes it possible to be implemented on low cost hardware platforms. Experiment results demonstrate the feasibility of the proposed algorithm on smooth feedrate planning and contour error control for continuous short line tool path.


      PubDate: 2013-10-03T09:15:16Z
       
  • Fabrication of Deep Micro Holes in Reaction-Bonded SiC by Ultrasonic
           Cavitation Assisted Micro EDM
    • Abstract: Publication date: Available online 30 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Pay Jun Liew , Jiwang Yan , Tsunemoto Kuriyagawa
      Ultrasonic vibration was applied to dielectric fluid by a probe-type vibrator to assist micro electrical discharge machining of deep micro holes in ceramic materials. Changes of machined hole depth, hole geometry, surface topography, machining stability and tool material deposition under various machining conditions were investigated. Results show that ultrasonic vibration not only induces stirring effect, but also causes cloud cavitation effect which is helpful for removing debris and preventing tool material deposition on machined surface. The machining characteristics are strongly affected by the vibration amplitude, and the best machining performance is obtained when carbon nanofibers are added into the vibrated dielectric fluid. As test pieces, micro holes having ten micron level diameters and high aspect ratios (>20) were successfully fabricated on reaction-bonded silicon carbide in a few minutes. The hybrid EDM process combining ultrasonic cavitation and carbon nanofiber addition is demonstrated to be useful for fabricating microstructures on hard brittle ceramic materials.
      Graphical abstract image

      PubDate: 2013-10-03T09:15:16Z
       
  • Investigation of influence of Fixture Layout on Dynamic Response of
           Thin-Wall Multi-Framed Work-piece in Machining
    • Abstract: Publication date: Available online 27 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Xiao-Jin Wan , Yan Zhang , Xin-Da Huang
      In the aerospace industry, milling of the thin-wall multi-framed work-piece (TMW) is a critical challenging task due to the mutually coupling dynamics of adjacent frames and side plates. Evaluation of the effect of fixture layout on the dynamic response of thin-walled work-piece is a critical measure to determine whether the designed fixture can meet the requirements for the tightly specified tolerance of the part. A new analytical technique is proposed to determine the effect of fixture layout on the dynamic response of TMW during machining. In this modeling process, a workpiece-fixture system may be equivalent as a thin-multi-span plate (TMSP) with intermediate line and point supports. And then, double functions of Euler-Bernoulli beam can be utilized to describe mode shape of a TMW on basis of a span-by-span approach. Further, a dynamic equation of work-piece-fixture system can be modeled by Lagrangian method in terms of new mode shape functions. Implementation of this technique is simple, enables avoidance of cumbersome mathematical calculations. Finally, the feasibility of the proposed approach is validated by a machining case.


      PubDate: 2013-09-29T19:36:21Z
       
  • Finite Element Modelling of Shear Angle and Cutting Force Variation
           Induced by Material Anisotropy in Ultra-precision Diamond Turning
    • Abstract: Publication date: Available online 23 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): W.B. Lee , H. Wang , C.Y. Chan , S. To
      This paper addresses a key theoretical problem in the mechanics of ultra-precision machining - shear angle prediction and cutting force variation induced by crystallographic anisotropy. The constitutive equation of crystal plasticity is implemented in the finite element modelling of chip formation at micro-scale to take into account the effect of crystallographic orientations of the work piece to be cut. The theoretical prediction of shear angle and cutting force variation reveals two distinguished phases of pre-compression and steady-state cutting in ultra-precision diamond turning. The predicted patterns of cutting force variation are in good agreement with published experimental results.


      PubDate: 2013-09-25T20:20:52Z
       
  • Methodology for the design of a thermal distortion compensation for large
           machine tools based in state-space representation with Kalman filter
    • Abstract: Publication date: Available online 19 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): E. Gomez-Acedo , A. Olarra , J. Orive , L.N. Lopez de la Calle
      A methodology for the design of a thermal distortion compensation system is presented which will assist the manufacturing processes to reach higher levels of accuracy when working with large machines in common shop floor environments. A parametric state-space representation was selected as model architecture, providing multiple inputs and outputs capability and a compact formulation that takes into account previous thermal states of the machine. Inputs for the model are spindle speed and temperatures of main motor gearbox and room air. Outputs are the estimations of the thermal drift of the machine tool centre point along the three axes in different positions within the working volume. Model parameters were numerically identified with initial experimental tests performed in a large gantry-type milling machine, measuring mentioned variables and also thermal distortion values using a reference artifact along with non-contact proximity sensors. Proposed model was finally verified with a new validation measurement in the machine. Obtained results revealed 80% of error reduction in the vertical axis which comprised 70% of total thermal effects and 50% in the longitudinal X axis which comprised 25% of total thermal effects. Also it was concluded that the model benefits from using valuable information about the machine state from previous spindle speed register instead of using only temperature values. Proposed methodology benefits from providing a feasible implementation in real shop floor conditions without the necessity of including additional temperature sensors or probing systems in the machine.


      PubDate: 2013-09-25T20:20:52Z
       
  • Stability prediction in radial immersion for milling with symmetric
           structure
    • Abstract: Publication date: Available online 25 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): C.M. Zheng , J.-J. Junz Wang
      In this study, an analytical approach is presented to find stability limits in terms of radial immersion for a given axial depth of cut, and vice versa. Under the assumption of axis-symmetric structure and using the zero order force model, the direction coefficient matrix is decoupled to reduce the 2D milling system to a 1D stability problem. The effect of the radial immersion and radial cutting coefficient on the system stability are explicitly represented through the eigenvalue function of the directional coefficient matrix. The resulting characteristic equation allows the limiting radial immersion be solved for a given axial immersion. A procedure is presented in obtaining the radial stability diagram, in which additional unstable island and secondary lobes are shown to exist besides the traditional lobes. Stability diagrams in both axial and radial immersion are presented to demonstrate the physical insights offered by the presented method. The model is validated by comparing with results from the existing analytical and numerical models.


      PubDate: 2013-09-25T20:20:52Z
       
  • Generalized Kinematics of Five-Axis Serial Machines with Non-Singular Tool
           Path Generation
    • Abstract: Publication date: Available online 18 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Jixiang Yang , Yusuf Altintas
      Typical five-axis machine tools have three translational and two rotary drives. This paper presents a generalized kinematics model that allows automatic configurations of all five-axis machine tools using screw theory. First, each kinematic element is modelled as a revolute joint, prismatic joint, workpiece or cutting tool. The kinematic elements are mathematically assembled through screw theory by using the base coordinate system. The general inverse kinematics solutions for both rotary and translational motions are evaluated. The singularities in five axis contouring are avoided by deforming splined tool orientation vectors. The tool orientation vectors are represented by a fifth degree B-spline curve in a quaternion space, while the movement of tool tip is represented by a fifth degree B-spline curve in the Cartesian space. Both splines, which form the C3 continuous tool path, are fitted to curve length parameter of the tool tip positions. If the tool path traverses the singular area of the machine, it is deformed by modifying the control points of the tool orientation spline in the quaternion space while respecting the machining tolerance. The proposed kinematics module, tool path generation algorithm and method for avoiding kinematic singularities are experimentally verified on a five-axis machine tool controlled by an in-house developed CNC system.


      PubDate: 2013-09-19T08:01:37Z
       
  • Optimum Selection of Variable Punch-die Clearance to Improve Tool Life in
           Blanking Non-symmetric Shapes
    • Abstract: Publication date: Available online 17 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Soumya Subramonian , Taylan Altan , Bogdan Ciocirlan , Craig Campbell
      Punch-die clearance is a well-known parameter affecting both tool life and edge quality of parts in blanking and piercing. Selecting the optimum or best punch-die clearance can give a significantly longer tool life by minimizing tool wear. Previous studies have shown the effect of punchdie clearance on various sheet materials and thicknesses during blanking of round parts while nonround geometries are more commonly found in industrial applications. Therefore, in this study, the effect of part geometry is considered to select the ‘best’ punch-die clearance to minimize tool wear. In blanking non-round geometries, the punch and die undergo non-uniform wear, with higher wear observed in areas with sharp radii and abrupt changes in geometry. In the present study, the effect of punch-die clearance on punch stress for blanking various shapes is investigated using Finite Element (FE) analysis. The punch-die clearance that gives the lowest value of the punch stress for the different part geometries is identified. A method is developed to select a geometry dependent variable punchdie clearance to obtain more uniform wear on the punch, thereby increasing the punch and die life.


      PubDate: 2013-09-19T08:01:37Z
       
  • Fundamental performance of MCF (Magnetic Compound Fluid) wheel in
           ultra-fine surface finishing of optical glass
    • Abstract: Publication date: Available online 16 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): L. Jiao , Y. Wu , X. Wang , H. Guo , Z. Liang
      The present work proposed a new semi-fixed abrasive ultra-fine finishing method for optical glass utilizing Magnetic Compound Fluid (MCF) wheel. This MCF wheel is actually produced by generating a thin uniform MCF slurry layer on the whole circumference surface of ring-shaped permanent magnets bitted by two non-magnetic plates. The MCF slurry is composed of nano-sized magnetite particle, micro-sized iron particle, several 10μm-sized α-cellulose fiber and sub-micro-sized abrasive particle that reacts to the magnetic field. As an initial step to develop the technique, in this paper the polishing principle using MCF wheel is described. The fundamental performances of the MCF wheel in the polishing of fused silica glass are investigated experimentally for different process parameters. Then the mechanism of material removal is discussed by the measurement of polishing force, the microscopic observation of the MCF layer structure and theoretical analysis of the magnetic field distribution on the circumference surface of the MCF wheel. The model of material removal is built in polishing with MCF wheel. The obtained results showed that (1) a better work surface and a larger material removal are obtained under the conditions of the smaller clearance and the higher magnet rotational speed; (2) both normal and tangential forces polishing decrease with the increasing working clearance and the decreasing wheel rotation speed, leading to the decreases in the material removal rate; (3) at the positions closer to both magnet edges with higher magnetic field strength, the polishing pressure is higher and the number of the active abrasive particles is larger, resulting in larger material removal rate. This study investigates a new semi-fixed-abrasive, ultra-fine finishing method for optical glass using a magnetic compound fluid (MCF) wheel. This MCF wheel generates a thin, uniform MCF slurry layer on the entire circumferential surface of a ring-shaped permanent magnet placed between two non-magnetic plates. The MCF slurry is composed of nano-sized magnetite particles, micron-sized iron particles, several 10 μm-sized α-cellulose fibres and sub-micron-sized abrasive particles that react to the magnetic field. Following modifications to the design of the MCF, experiments were conducted to evaluate the performance of the modified wheel in spot-polishing fused silica glass. This paper describes the modifications to the MCF wheel and the experimental setup used to measure its performance. The improvement of the modified wheel over the unmodified wheel in terms of material removal and surfaces roughness is experimentally confirmed. The effects of the wheel rotational speed and the clearance between the wheel and the workpiece on material removal and the workpiece surface roughness are investigated. The polishing forces are measured, the structure of the MCF slurry is examined and the magnetic field distribution is analysed. A model of material removal in polishing with the modified MCF wheel is developed. The results indicate the following: (1) more material was removed, i.e., greater spot depths, and better surfaces were obtained in the regions that were near the edges of the magnet; (2) the modified MCF wheel performed much better than the unmodified wheel in terms of material removal and surface roughness, e.g., 3.1µm vs. 1.7µm for the maximum spot depth, 0.04mm3 vs. 0.0088mm3 for the volume of material removed and Ra = 5.624nm vs. 14.67nm for the surface roughness; (3) a better work surface and greater material removal were obtained with smaller working clearances and higher wheel rotational speeds.


      PubDate: 2013-09-19T08:01:37Z
       
  • Accuracy Evaluation of Machine Tools by Modeling Spherical Deviation Based
           on Double Ball-bar Measurements
    • Abstract: Publication date: Available online 17 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Kwang-Il Lee , Seung-Han Yang
      In this study, the accuracy of a machine tool was evaluated by modeling the spherical deviation based on double ball-bar measurements under unloaded conditions. Circular measurement paths on the XY -, YZ -, and ZX-planes were planned, and three linear axis drives were commanded to follow the paths describing a nominal sphere. The spherical deviation, defined as the maximum radial range of deviations around a least-squares sphere, is affected by the accuracies of the three linear axes together. Therefore, the spherical deviation represents the accuracy of machine tools by quantifying the effect of the accuracies of three linear axes, whereas the circular deviation only quantifies the accuracies of two linear axes among the three linear axes. In this experimental study, spherical deviations of vertical/horizontal machine tools were measured and analyzed under various nominal lengths of a double ball-bar for various feed rates. The measurement uncertainty of the measured spherical deviation was investigated to determine the confidence interval.


      PubDate: 2013-09-19T08:01:37Z
       
  • Internal characterization and hole Formation mechanism in the laser
           PERCUSSION drilling process
    • Abstract: Publication date: Available online 9 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): I Arrizubieta , A. Lamikiz , S. Martínez , E. Ukar , I. Tabernero , F. Girot
      Laser percussion drilling is increasing its relevance in many industrial applications, being used particularly in the aircraft industry in performing the micro-holes in nickel based alloys turbine blades for cooling, or stainless steel medical components drilling, which require small holes size and quality. Laser percussion drilling process presents extremely high speed for high aspect ratio holes. Moreover, the quality and accuracy of the holes can be excellent if the optimal parameters are set. The laser percussion drilling process is usually performed with specific equipment, including lasers that achieve high peak powers of picoseconds duration. These systems are usually dedicated exclusively to laser drilling operation. It is also very common to perform this process using the parameters suggested by the manufacturer of the equipment and without any consideration about the mechanism of formation of the hole. On the other hand, laser percussion drilling is performed by a sequence of pulses on the part surface. Each pulse removes a certain amount of material. The energy and duration of pulses set the amount of removed material by each one. This work discusses the mechanisms of formation of the holes in the laser percussion drilling process of an AISI 304 plate, evaluating the removed material volume in each laser pulse and obtaining the evolution of the hole geometry for the complete pulse sequence. In addition, this experimental analysis has been apply also for the development of a numerical model that can simulate the resulting hole geometry for different pulse sequences.


      PubDate: 2013-09-11T06:24:33Z
       
  • Temperature of internally-cooled diamond-coated tools for dry-cutting
           titanium
    • Abstract: Publication date: Available online 3 September 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): T. Minton , S Ghani , F. Sammler , R. Bateman , P. Fürstmann , M. Roeder
      The role of cutting fluids is well known for the importance of removing heat from the cutting edge, lubricating the sliding chip contact and transporting the metal chips away from the cutting zone. Dry machining leads to increased cutting temperatures and higher wear rates resulting in shorter tool life; this is particularly evident in the cutting of high strength materials. Diamond coated cutting inserts are not usually considered for machining titanium due to rapid oxidation of the coating at the temperatures typical of titanium machining. This paper examines the formation of hot-spots on the rake face during dry and near-dry turning of titanium using conventional cemented carbide inserts. Machining performance is assessed by measurement of tool wear and tool life. Trials with an internally cooled tool with a specially designed, diamond coated insert have shown that the heat from the cutting operation can be rapidly diffused over the entire surface of the insert and thus successfully drawn away from the tool via closed loop recirculation of coolant through the tool holder. This enables wear to be inhibited by management of rake face temperature to keep it below the critical temperatures at which these prominent wear mechanisms operate. Measurements of change in coolant temperature before and after circulation are used to quantify the heat removed from the cutting process. The low friction coefficient and high thermal conductivity of diamond, assisted by the indirect cooling, results in longer tool life whilst maintaining high standards of surface finish.


      PubDate: 2013-09-04T00:55:25Z
       
  • Measurement and finite element simulation of micro-cutting temperatures of
           tool tip and workpiece
    • Abstract: Publication date: Available online 29 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Guang Chen , Chengzu Ren , Pan Zhang , Kuihu Cui , Yuanchen Li
      Temperature generates in micro-scale cutting process has a great effect on cutting performance due to centralized heat generation. In this study, a set of micro-cutting experiments (8μm/r≤f≤50μm/r) were carried out to measure temperatures in micro-cutting process with high accuracy. A fast-response thermocouple with a property of self-renewing was installed in a cylinder workpiece to measure the temperatures of workpiece and tool tip simultaneously. In each test, temperature of the workpiece surface is obtained just before the hot junction of thermocouple is machined. When the hot junction is machined, the tested maximum temperature is recognized as the temperature of tool tip. In parallel, an energy density-based ductile failure material model is developed to simulate the micro-cutting process by finite element method. In simulation, when mesh distribution is changed, the predicted forces with same energy density G ε are closer to the forces at original mesh distribution than those predicted by same energy G f . Consequently, the energy density-based ductile failure material model can reduce mesh dependence in different mesh distribution conditions. Under new mesh distribution, Temperatures of the workpiece surface and tool tip are identified in the predicted micro-cutting temperature field. The predicted micro-cutting temperatures of workpiece surface and tool tip are very close to the experimental results. Further, the variation of temperature and its relationship with chip curling are also discussed.


      PubDate: 2013-08-30T23:06:20Z
       
  • A theoretical and experimental study of surface generation under spindle
           vibration in ultra-precision raster milling
    • Abstract: Publication date: Available online 26 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): S.J. Zhang , S. To
      In ultra-precision raster milling (UPRM), the impulse spindle vibration induced by the impulse-like cutting forces is intrinsic and special mechanism majorly influencing surface topography. It is fundamentally distinctive with the step spindle vibration induced by the step-like cutting forces in turning. However, no work has been conducted to study surface generation under the impulse spindle vibration in UPRM in depth. Consequently, this paper theoretically and experimentally elaborates that in UPRM, (i) the impulse spindle vibration includes the axial, radial and coupled-tilting spindle vibration with damping; (ii) the excitation frequency of the impulse-like cutting forces, i.e. spindle speed, determines the spindle vibration characteristics, i.e. synchronous or asynchronous spindle vibration; (iii) the coupled-tilting spindle vibration is a predominant factor influencing surface generation; and (iv) the irregular spindle-vibration waves induced by the impulse spindle vibration produce one of the irregular, lattice-like and stripe patterns or their hybrids at a milled surface.
      Graphical abstract image

      PubDate: 2013-08-26T20:08:51Z
       
  • A Parametric Interpolator with Minimal Feed Fluctuation for CNC Machine
           Tools using Arc-length Compensation and Feedback Correction
    • Abstract: Publication date: Available online 16 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Huan Zhao , LiMin Zhu , Han Ding
      Traditionally, approximation methods are utilized in the parametric interpolation because of the nonanalytic relationship between the spline parameter and the arc length. The approximation error has been considered as the source of the feedrate fluctuation. This paper shows that the discrepancy between the desired tool path and the target trajectory of the motion system is another primary source, and presents a feedback interpolator to eliminate the feedrate fluctuation. To evaluate the initial parameter value for the interpolator, an arc-length based Taylor's expansion with arc-length compensation is proposed, which alleviates greatly the feedrate command error caused by the trajectory deviation. Then, a feedback correction scheme is developed to further reduce the feedrate command error that results from the approximation error. Both computational load analysis and numerical simulations are conducted, and the results show that the present interpolator has very good performance in both efficiency and accuracy, thus is a good choice for high speed and high precision CNC machines.


      PubDate: 2013-08-18T22:59:57Z
       
  • Modeling of material removal rate in Electric Discharge Grinding process
    • Abstract: Publication date: Available online 15 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): M.K. Satyarthi , Pulak M. Pandey
      The mechanism of material removal in electric discharge grinding (EDG) is very complex due to interdependence of mechanical and thermal energies responsible for material removal. Therefore, on the basis of conceived process physics for material removal, an attempt has been made to predict the material removal rate (MRR). The proposed mathematical model is based on the fundamental principles of material removal in electric discharge machining (EDM) and conventional grinding processes. The inter-dependence of the thermal and mechanical phenomena has been realized by scanning electron microscopy (SEM) characterization of the samples machined at different processing conditions. The key input process parameters like pulse on time, pulse current, gap voltage, duty cycle, pulse off time, frequency, depth of cut, wheel speed and table speed are co-related with MRR for three distinct idealized processing conditions. The constant showing the extent of interdependence of two phenomena were evaluated by experimental data. The obtained expressions of MRR have been validated for processing conditions other than those used for obtaining constants. It was found that the discharge energy plays prominent role in material removal. The percentage difference in experimental findings and theoretical predictions was found to be less than 3%.


      PubDate: 2013-08-18T22:59:57Z
       
  • On the Selection of Constitutive Laws Used in Modeling Friction Stir
           Welding
    • Abstract: Publication date: Available online 13 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Katherine Kuykendall , Tracy Nelson , Carl Sorensen
      Discrepancies in friction stir welding model predictions for temperature, strain, and strain rate may be due to material, process parameters, boundary conditions, heat transfer properties, or constitutive laws. The focus of this work is to investigate the effect of the constitutive law on friction stir welding model predictions. This paper provides a description of constitutive laws with their uses and limitations to facilitate the selection of an appropriate constitutive law for a given modeling objective. None of the path-independent constitutive laws evaluated in this paper has been validated over the full range of strain, strain rate, and temperature in friction stir welding. Holding all parameters other than constitutive law constant in a friction stir weld model for AA 5083 resulted in temperature differences of up to 21%. Varying locations for maximum temperature difference indicate that the constitutive laws resulted in different temperature profiles. Peak strains and strain rates predicted vary by up to 130% and 166%, respectively. Predicted flow stress profiles are also affected by the choice of constitutive law.


      PubDate: 2013-08-14T19:54:33Z
       
  • Influence of the clearance angle on the cutting efficiency of blunt,
           octahedral-shaped diamonds in an active filler alloy
    • Abstract: Publication date: Available online 8 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Robert Transchel , Flurin Heini , Josef Stirnimann , Friedrich Kuster , Christian Leinenbach , Konrad Wegener
      For increasing the efficiency of processes with non-defined cutting edges a new approach based on an experimental study using blunt, octahedral-shaped diamond grains is presented. This approach considers the orientation of the flank face towards the cutting direction and enables the determination of the ploughing share caused by negative clearance angles. Positive clearance angles enable an efficient removal of the ductile work piece material while cutting force ratios up to 0.68 were achieved in this study. This amelioration of the efficiency increase during the material contact caused by positive clearance angles is characterised by the absence of a white layer in the subsurface zone of machined material, which could be observed when grains with negative clearance angle were applied.


      PubDate: 2013-08-10T15:11:00Z
       
  • IFC - Editorial board
    • Abstract: Publication date: October 2013
      Source:International Journal of Machine Tools and Manufacture, Volume 73




      PubDate: 2013-08-10T15:11:00Z
       
  • ENERGY DISSIPATION IN MODULATION ASSISTED MACHINING
    • Abstract: Publication date: Available online 3 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Ho Yeung , Narayan K. Sundaram , James B. Mann , W. Dale Compton , Srinivasan Chandrasekar
      The specific energy in modulation assisted machining (MAM) – machining with superimposed low frequency (< 1,000Hz) modulation in the feed direction – is estimated from direct measurements of cutting forces. Reductions of up to 70 percent in the energy are observed relative to that in conventional machining, when cutting ductile metals such as copper and Al 6061T6. Evidence based on chip structures and strains, stored energy of cold work, recrystallization, and finite element simulation of chip formation, is presented to show that this reduction is due to smaller strain levels in chips created by MAM. A simple geometric ratio of the length to thickness of the ‘undeformed chip’, which can be estimated a priori from MAM and machining parameters, is shown to be a predictor of the transient chip formation conditions that result in the reduction in specific energy and deformation levels.


      PubDate: 2013-08-06T13:24:26Z
       
  • An efficient linear approximation of acceleration method for milling
           stability prediction
    • Abstract: Publication date: Available online 6 August 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Tao Huang , Xiaoming Zhang , Xiaojian Zhang , Han Ding
      Chatter stability predictions catch much attention during machining operations in modern automotive and aerospace industry. This paper presents a novel time domain semi-analytical method for milling stability prediction based on linear acceleration approximation. Firstly, the milling dynamics considering the regenerative effect is presented as a linear time-delay system with periodic coefficients. The second step is to equally discretize the time duration of the forced vibration of the tooth passing period into small intervals where acceleration of the flexible cutter is approximated by linearly interpolating between the two boundary values, while the free vibration is analytically solved. Then, recursive formulas with constant recursive matrices are found for the presentation of relations between initial and final cutter motions (including position, velocity and acceleration) of each small time interval. Employing the method of weighted residuals over each time interval, discrete maps are constructed which relate motions of a period to the corresponding values one period earlier. Finally, the eigenvalues of the transition matrix are used to determine stability based on Floquet theory. By using the benchmark examples in literatures, the convergence and computational time of the proposed method are compared with those of the semi-discretization methods (SDMs), full-discretization method (FDM) and numerical integration method (NIM). The results verify the validity of the proposed approach, and the presented method is proved to be computationally highly efficient.


      PubDate: 2013-08-06T13:24:26Z
       
  • 2D/3D ground surface topography modeling considering dressing and wear
           effects in grinding process
    • Abstract: Publication date: Available online 26 July 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): J.L. Jiang , P.Q. Ge , W.B. Bi , L. Zhang , D.X. Wang , Y. Zhang
      Roughness is usually regarded as one of the most important factors to evaluate the quality of grinding process and ground surface. Many grinding parameters are affecting ground surface roughness with different extents, however, the most influential factors are wheel dressing and wear effects which were unfortunately not get seriously attention in the previous researches. On the other hand, as a most common indicator, roughness is only a statistical evaluation which is not enough to describe the topography characteristics of a surface, especially under higher demands on grinding process and functional ground surface quality. Thus in this work, a 2D and 3D ground surface topography models were established based on the microscopic interaction mechanism model between grains and workpiece in grinding contact zone. In this study, besides grinding parameters, the wheel dressing and wear effects were taken into consideration, including dressing depth, dressing lead, geometry of diamond dressing tool and wear effects of both wheel and diamond dressing tool. A dressing and wear profile line, L dw, which will describe how the grains′ shapes are changed, was established and added into a former 2D ground surface roughness prediction model. In order to obtain a better visual effect, a 3D topography model was established which is based on the interaction situations in real grinding process. Both 2D and 3D models will predict ground surface roughness more precisely and stably than traditional models by comparing with a dressing lead single-factor experiment. Results also showed that the selection of dressing parameters and dressing tools can refer to the formed shape of L dw by comparing with grinding depth, a e, and the dressing lead should be carefully chosen which will greatly influence ground surface topography the most.


      PubDate: 2013-07-29T10:26:24Z
       
  • Enhancement of the Machinability of Silicon by Hydrogen Ion Implantation
           for Ultra-precision Micro-cutting
    • Abstract: Publication date: Available online 27 July 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): S. To , H. Wang , E.V. Jelenković
      This paper presents the implementation method of surface modification by hydrogen ion implantation in silicon on the enhancement of machinability of silicon by facilitating the brittle-to-ductile transition. The distribution of the implanted hydrogen ions and induced displacements in the sub-surface of silicon wafer is visualised through modelling. The micro-cutting experiments are conducted on ultra-precision raster milling to verify the enhancement effect on the machinability of silicon.


      PubDate: 2013-07-29T10:26:24Z
       
  • Pre-compensation of contour errors in Five-Axis CNC machine tools
    • Abstract: Publication date: Available online 20 July 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Ke Zhang , Alexander Yuen , Yusuf Altintas
      This paper presents an analytical prediction and compensation of contouring errors in five-axis machining of splined tool paths. The position commands are first fitted to piecewise quintic splines while respecting velocity, acceleration and jerk continuity at the spline joints. The transfer function of each servo drive is kept linear by compensating the disturbance effect of friction with a feed-forward block. Using the analytically represented five-axis, splined tool path, splined tracking errors and kinematic model of the five-axis machine tool, contouring errors are predicted ahead of axis control loops. The contouring errors are decoupled into three linear and two rotary drives, and the position commands are modified before they are sent to servo drives for execution. The proposed method has been experimentally demonstrated to show significant improvement in the accuracy of contouring five-axis tool paths.


      PubDate: 2013-07-21T07:26:38Z
       
  • Mechanisms involved in the improvement of Inconel 718 machinability by
           Laser Assisted Machining (LAM)
    • Abstract: Publication date: Available online 8 July 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Virginia Garcia Navas , Iban Arriola , Oscar Gonzalo , Josu Leunda
      The aim of the present research work has been to gain a broader understanding of how or why laser assisted machining (LAM) improves machinability of Inconel 718, a hard-to-machine material of interest in the aeronautic industry. This has been accomplished by, first, running short run tests to determine the laser parameters and configuration for which highest force reductions are obtained and also to determine the effect of cutting parameters (feed, cutting speed and depth of cut) on force reduction. Secondly, long run tests have been performed in order to analyze process variables such as cutting forces, tool wear and surface roughness. Temperatures and hardness have been also measured in order to gain a broader perspective of the process. Experimental results have demonstrated that LAM improves machinability of Inconel 718 since machining forces and final surface roughness are reduced. The novelty reached with the present research work is the identification of three mechanisms associated to the laser heating as the responsible of this machinability improvement: material yield strength reduction, material base hardness reduction (only in precipitation hardened Inconel 718) and elimination of the work hardening generated in previous machining passes. The reduction of the work hardening leads also to a lower notch wear that limits the risk of sudden failure of the cutting tool and thus the wear mode is changed to flank wear, which leads to a controllable tool life and better surface roughness.


      PubDate: 2013-07-10T01:33:01Z
       
  • On the influence of single grit micro-geometry on grinding behavior of
           ductile and brittle materials
    • Abstract: Publication date: Available online 2 July 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): D. Axinte , P. Butler-Smith , C. Akgun , K. Kolluru
      Recently it has been proven that highly engineered grinding/polishing tools can be manufactured with controlled shapes and distributions of abrasives. This research is directed to understand the influence of the shapes of the micro-cutting edges (i.e. circular/square/triangular base frustums generated by laser ablation), emulating grits of these engineered abrasive tools, on the material removal mechanism for workpiece materials of different mechanical properties (ductile − copper, brittle − sapphire). 2D/3D micro-profilometry, scanning electron microscopy supported by sensory signals (e.g. cutting forces) enabled to understand the relationship between the ploughing/shearing of ductile and brittle behaviour materials upon the number and orientation of the cutting edges that emulate the tested single grit shapes. It was found that for copper the increase in number of cutting edges (NoCE) of the grits results in more localised material pile-up and the reduction of plastic deformations with inherent decrease of specific cutting force; nevertheless, it became apparent that to diminish specific cutting forces, both NoCE and effective contact area between the grit and workpiece material need to be considered. For sapphire, shearing /fracturing phenomena were preponderant in the material removal mechanism when using square/triangular shaped grits while major plastic deformations were found for circular base frustum; significant reduction of specific cutting forces were noted with the increase of NoCE. This preliminary work enables the understanding on the implications of using particular grit shapes when utilising the novel edge-controlled grinding/polishing tools for machining ductile/brittle workpiece materials.


      PubDate: 2013-07-05T06:49:20Z
       
  • 5-axis local corner rounding of linear tool path discontinuities
    • Abstract: Publication date: Available online 5 June 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Xavier Beudaert , Sylvain Lavernhe , Christophe Tournier
      5-axis high speed machine tools are widely used in industry. Most of the time, the tool path is described with linear segments (G1) which leads to tangency discontinuities between blocks. The aim of this paper is to smooth the tool path geometry using a 5-axis corner rounding method suitable for accelerationTEill a challenge due to the difficulties linked to the smoothing of the orientation. The proposed corner rounding model allows to control precisely the contour and orientation tolerances in the workpiece coordinate system for 3 and 5-axis tool path. To smooth the tool tip position and the tool orientation in the corner, 5-axis tool paths are represented by two B-Spline curves. The main difficulty is the connection between the initial tool path and the newly inserted smoothing portion. To obtain a smooth connection of the orientation a parametrization spline is required to link the bottom and top B-Spline parameters. This algorithm is integrated to a feedrate interpolator which controls a 5-axis milling machine equipped with an Open CNC.


      PubDate: 2013-06-08T02:04:15Z
       
  • Investigations of yield stress, fracture toughness, and energy
           distribution in high speed orthogonal cutting
    • Abstract: Publication date: Available online 31 May 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): Wang Bing , Liu Zhanqiang , Yang Qibiao
      This paper presents a novel prediction method of the yield stress and fracture toughness for ductile metal materials through the metal cutting process based on Williams' Model [38]. The fracture toughness of the separation between the segments in serrated chips in high speed machining is then deduced. In addition, an energy conservation equation for high speed machining process, which considers the energy of new created workpiece surfaces, is established. The fracture energy of serrated chips is taken into the developed energy conservation equation. Five groups experiments are carried out under the cutting speeds of 100, 200, 400, 800 and 1,500m/min respectively. The cutting forces are measured using three-dimensional dynamometer and the relevant geometrical parameters of chips are measured with the aid of optical microscope. The experiment results show that the yield stress of machined ductile metal material presents an obviously increasing trend with the cutting speed increasing from 100 to 800m/min while it decreases when the cutting speed increases to 1500m/min further. Meanwhile, the fracture toughness between the chip and bulk material displays a slightly increasing tendency. In high speed machining, the fracture toughness of the separation between the segments in serrated chips also presents increasing trend with the increasing cutting speed, whose value is much greater than that between the chip and bulk material. In the end, the distribution of energy spent in cutting process is analyzed which mainly includes such four portions as plastic deformation, friction on the tool-chip interface, new generated surface and chip fracture. The results show that the proportion of plastic deformation is the largest one while it decreases with the cutting speed increasing. However, the proportions of energy spent on new created surface and chip fracture increase due to the increasing of both the chip's fracture area and the fracture toughness.


      PubDate: 2013-06-03T21:31:18Z
       
  • Friction behaviour in strip draw test of pre-stretched high strength
           automotive aluminium alloys
    • Abstract: Publication date: Available online 10 May 2013
      Source:International Journal of Machine Tools and Manufacture
      Author(s): I.G. Masters , D.K. Williams , R. Roy
      Aluminium alloys are being increasingly used in the automotive industry as a means of light-weighting the vehicle body to reduce emissions. The forming characteristics of aluminium alloys, however, differ from those of conventional deep-drawing quality materials, and the drive to reduce vehicle development times has led to reliance on simulation of forming operations to establish feasibility in the early design stages. It is known that friction has a major influence on the forming characteristics of a material and changes as the material plastically deforms and surface roughness increases, causing a transition from hydrodynamic to a mixed friction regime where metal to metal contact is increased. In the simulation environment however, friction is usually assumed to be constant. The development of higher strength alloys requiring higher forming forces suggest that a constant friction value may not always be a valid assumption. In this paper the friction behaviour of three commercially available automotive aluminium grades are compared, at different levels of strain, using a strip draw test. The results show that for a material with a standard mill finish friction is anisotropic, remaining so even at relatively high strains and the anisotropy is independent of the direction of strain. The friction coefficient increases with the level of strain but the use of solid wax lubricants helps to overcome this maintaining a uniform friction at strains up to 10%. For aluminium with an EDT finish the roughening effects due to plastic strain are completely overcome and again a constant friction value is valid. In some alloys the formation of stretcher strains also help to reduce the metal to metal contact promoting hydrodynamic friction and a constant friction coefficient at lower strains.


      PubDate: 2013-05-11T02:04:27Z
       
 
 
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