The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform

Kevin Y Chou - One of the best experts on this subject based on the ideXlab platform.

  • IMECE2005-80323 AN INVESTIGATION ON CUTTING TOOL TEMPERATURES IN COMPOSITE MACHINING ASSISTED WITH HEAT-PIPE COOLING
    2020
    Co-Authors: Jie Liu, Kevin Y Chou, Mark T North, Kirk A Bennett
    Abstract:

    ABSTRACT Metal matrix composites (MMC) are difficult to cut materials, and yet only diamond tools have been successfully utilized for such machining applications. Wear of diamondcoated tools is characterized by catastrophic coating failure (peeling off) due to the adhered work materials at the Flank Wear-Land surface and the high stress developed at the coatingsubstrate interface, associated with high temperatures, because of very different thermal expansion coefficients. Temperature reductions, therefore, may delay the onset of the coating failure and offer tool life extension. A passive heat-dissipation device, heat-pipe, has been tested for cutting temperature reductions in MMC machining. Though it is intuitive that heat pipes may enhance heat transfer and plausibly reduce the tool temperatures, heat pipes may also increase heat partitioning into the tool, and complicate its effects on the heat removal and temperature reduction efficiency. This paper reports aluminum composite machining by diamond-coated tools and investigates the heat-pipe effects on tool temperature reductions. Numerical simulation of heat conduction in the cutting tool system was performed to evaluate cutting tool temperatures without and with a heat-pipe. A 3-D thermal model of the cutting tool system including coating, insert substrate, and tool holder was established. The heat source was characterized as a heat flux, a portion of the frictional heat flux at the rake face, over the chip-tool contact area. To determine the heat-partition coefficient, a separate 2-D chip model was established with a heat flux, balanced the total rake-face heat flux, over the contact and moving with the chip speed. With the tool and chip thermal models and by matching the average temperature at the tool-chip contact of the two models, the heat partition coefficient can be numerically determined. The model has been used to evaluate how the heat-pipe modifies the cutting tool temperatures. Applying heat-pipe cooling inevitably increases the heat partition into the tool despite the enhanced heat dissipation. However, the heat pipe still effectively reduces the tool-chip contact temperatures, depending upon machining conditions. Cutting tool temperatures have also been measured in machining using thermocouples. The simulation results reasonably agree with the experimental measurements

  • short communication characterizations of cutting tool Flank Wear Land contact
    2007
    Co-Authors: Kevin Y Chou
    Abstract:

    Metal deposition at the tool Flank Wear-Land during machining is a common phenomenon, especially in machining aluminum alloys and annealed steels. The cause of metal deposit has not been studied and the characteristics of the Wear-Land and deposit contact are not completely known. In this study, a turning test was conducted using tungsten carbide (WC) tools with pre-generated Wear-Land to machine an aluminum alloy. The WC tools after machining were prepared by metallographic means to expose the cross-section of the interfacial zone. The metallographic samples were analyzed using etching, optical microscopy, scanning electron microscopy, energy dispersive by X-ray analysis, and microhardness testing. The major findings include the following. The metal deposit is resistant to common etching solutions, shows high carbon and oxygen concentrations, and has a very high hardness, all indicating fine microstructures resulted from the thermomechanical, and possibly chemical, process. The WC at the contact interface has a thin heat-affected zone showing reduced hardness and different microstructures. In addition, the Flank Wear-Land subsurface has a decreased tungsten concentration, but an increased carbon concentration. After removing the metal deposit, the Flank Wear-Land consistently shows two topographically distinct zones when the Wear-Land is large; one close to the cutting edge has a plastic-contact feature and the other has an elastic-contact feature. No significant difference in terms of microstructures and compositions was identified, except that the plastic-contact zone was softer than the elastic-contact zone. © 2007 Elsevier B.V. All rights reserved.

  • thermal modeling for white layer predictions in finish hard turning
    International Journal of Machine Tools & Manufacture, 2005
    Co-Authors: Kevin Y Chou, Hui Song
    Abstract:

    Abstract Part thermal damage is a process limitation in finish hard turning and understanding process parameter effects, especially, tool Wear, on cutting temperatures is fundamental for process modeling and optimization. This study develops an analytical model for cutting temperature predictions, in particular, at the machined-surfaces, in finish hard turning by either a new or worn tool. A mechanistic model is employed to estimate the chip formation forces. Wear-Land forces are modeled using an approach that assumes linear growth of plastic zone on the Wear-Land and quadratic decay of stresses in elastic contact. Machining forces and geometric characteristics, i.e. shear plane, chip–tool contact, and Flank Wear-Land, approximate the heat intensity and dimensions of the shear plane, rake face, as well as Wear-Land heat sources. The three heat sources are further discretized into small segments, each treated as an individual rectangular heat source and subsequently used to calculate temperatures using modified moving or stationary heat-source approaches. Temperature rises due to all heat-source segments are superimposed, with proper coordinate transformation, to obtain the final temperature distributions due to the overall heat sources. All heat sources are simultaneously considered to determine heat partition coefficients, both at the rake face and Wear-Land, and evaluate the final temperature rises due to the combined heat-source effects. Simulation results show that, in new tool cutting, maximum machined-surface temperatures are adversely affected by increasing feed rate and cutting speed, but favorably by increasing depth of cut. In worn tool cutting, Flank Wear has decisive effects on machined-surface temperatures; the maximum temperature increases 2–3 times from 0 to 0.2 mm Wear-Land width. White layers (phase-transformed structures) formed at the machined-surfaces have been used to experimentally validate the analytical model by investigating tool nose radius effects on the white layer depth. The experimental results show good agreement with the model predictions. The established model forms a framework for analytical predictions of machined-surface temperatures in finish hard turning that are critical to part surface integrity and can be used to specify a tool life criterion.

  • experimental investigation on cubic boron nitride turning of hardened aisi 52100 steel
    Journal of Materials Processing Technology, 2003
    Co-Authors: Kevin Y Chou, Christopher J Evans, Moshe M Barash
    Abstract:

    Abstract This study investigated the performance and Wear behavior of different cubic boron nitride (CBN) tools in finish turning of hardened AISI 52100 steel. Tool performance was evaluated based on the part surface finish and the tool Flank Wear. Wear conditions of CBN cutting tools were primarily characterized by scanning electron microscopy (SEM). Machining results showed that low CBN content tools (CBN-L) consistently perform better than high CBN content counterparts (CBN-H), despite the CBN-L has inferior mechanical properties. The Flank Wear rates were proportional to cutting speed and CBN-H showed accelerated thermal Wear associated with high cutting temperatures. Reducing depth of cut would only improve surface finish to CBN-L, but not to CBN-H, despite similar Wear rates. The transferred layer on the Flank Wear Land may result in adhesion of the binder compound and significantly affect the tool Wear process. The metallic binder in CBN-H has stronger affinity to the transferred layer and may result in plucking-out of CBN particles and consequent severe abrasive Wear.

  • experimental investigation on cbn turning of hardened aisi 52100 steel
    Journal of Materials Processing Technology, 2002
    Co-Authors: Kevin Y Chou, Christopher J Evans, Moshe M Barash
    Abstract:

    Abstract This study investigated the performance and Wear behavior of different cubic boron nitride (CBN) tools in finish turning of hardened AISI 52100 steel. Tool performance was evaluated based on the part surface finish and the tool Flank Wear. Wear conditions of CBN cutting tools were primarily characterized by scanning electron microscopy (SEM). Machining results showed that low CBN content tools (CBN-L) consistently perform better than high CBN content counterparts (CBN-H), despite the CBN-L has inferior mechanical properties. The Flank Wear rates were proportional to cutting speed and CBN-H showed accelerated thermal Wear associated with high cutting temperatures. Reducing depth of cut would only improve surface finish to CBN-L, but not to CBN-H, despite similar Wear rates. The transferred layer on the Flank Wear Land may result in adhesion of the binder compound and significantly affect the tool Wear process. The metallic binder in CBN-H has stronger affinity to the transferred layer and may result in plucking out of CBN particles and consequent severe abrasive Wear.

Gaobo Xiao - One of the best experts on this subject based on the ideXlab platform.

  • the relation between chip morphology and tool Wear in ultra precision raster milling
    International Journal of Machine Tools & Manufacture, 2014
    Co-Authors: Guoqing Zhang, Gaobo Xiao
    Abstract:

    Abstract In the field of ultra-precision machining, the study of the relation between chip morphology and tool Wear is significant, since tool Wear characteristics can be reflected by morphologies of cutting chips. In this research, the relation between chip morphology and tool Flank Wear is first investigated in UPRM. A cutting experiment was performed to explore chip morphologies under different widths of Flank Wear Land. A geometric model was developed to identify the width of Flank Wear Land based on chip morphology. Theoretical and experimental results reveal that the occurrence of tool Flank Wear can make the cutting chips truncated at both their cut-in and cut-out sides, and reduce the length of cutting chips in the feed direction. The width of truncation positions of the cutting chip can be measured and used to calculate the width of Flank Wear Land with the help of the mathematical model. The present research is potentially used to detect tool Wear and evaluate machined surface quality in intermittent cutting process.

Moshe M Barash - One of the best experts on this subject based on the ideXlab platform.

  • experimental investigation on cubic boron nitride turning of hardened aisi 52100 steel
    Journal of Materials Processing Technology, 2003
    Co-Authors: Kevin Y Chou, Christopher J Evans, Moshe M Barash
    Abstract:

    Abstract This study investigated the performance and Wear behavior of different cubic boron nitride (CBN) tools in finish turning of hardened AISI 52100 steel. Tool performance was evaluated based on the part surface finish and the tool Flank Wear. Wear conditions of CBN cutting tools were primarily characterized by scanning electron microscopy (SEM). Machining results showed that low CBN content tools (CBN-L) consistently perform better than high CBN content counterparts (CBN-H), despite the CBN-L has inferior mechanical properties. The Flank Wear rates were proportional to cutting speed and CBN-H showed accelerated thermal Wear associated with high cutting temperatures. Reducing depth of cut would only improve surface finish to CBN-L, but not to CBN-H, despite similar Wear rates. The transferred layer on the Flank Wear Land may result in adhesion of the binder compound and significantly affect the tool Wear process. The metallic binder in CBN-H has stronger affinity to the transferred layer and may result in plucking-out of CBN particles and consequent severe abrasive Wear.

  • experimental investigation on cbn turning of hardened aisi 52100 steel
    Journal of Materials Processing Technology, 2002
    Co-Authors: Kevin Y Chou, Christopher J Evans, Moshe M Barash
    Abstract:

    Abstract This study investigated the performance and Wear behavior of different cubic boron nitride (CBN) tools in finish turning of hardened AISI 52100 steel. Tool performance was evaluated based on the part surface finish and the tool Flank Wear. Wear conditions of CBN cutting tools were primarily characterized by scanning electron microscopy (SEM). Machining results showed that low CBN content tools (CBN-L) consistently perform better than high CBN content counterparts (CBN-H), despite the CBN-L has inferior mechanical properties. The Flank Wear rates were proportional to cutting speed and CBN-H showed accelerated thermal Wear associated with high cutting temperatures. Reducing depth of cut would only improve surface finish to CBN-L, but not to CBN-H, despite similar Wear rates. The transferred layer on the Flank Wear Land may result in adhesion of the binder compound and significantly affect the tool Wear process. The metallic binder in CBN-H has stronger affinity to the transferred layer and may result in plucking out of CBN particles and consequent severe abrasive Wear.

Guoqing Zhang - One of the best experts on this subject based on the ideXlab platform.

  • the relation between chip morphology and tool Wear in ultra precision raster milling
    International Journal of Machine Tools & Manufacture, 2014
    Co-Authors: Guoqing Zhang, Gaobo Xiao
    Abstract:

    Abstract In the field of ultra-precision machining, the study of the relation between chip morphology and tool Wear is significant, since tool Wear characteristics can be reflected by morphologies of cutting chips. In this research, the relation between chip morphology and tool Flank Wear is first investigated in UPRM. A cutting experiment was performed to explore chip morphologies under different widths of Flank Wear Land. A geometric model was developed to identify the width of Flank Wear Land based on chip morphology. Theoretical and experimental results reveal that the occurrence of tool Flank Wear can make the cutting chips truncated at both their cut-in and cut-out sides, and reduce the length of cutting chips in the feed direction. The width of truncation positions of the cutting chip can be measured and used to calculate the width of Flank Wear Land with the help of the mathematical model. The present research is potentially used to detect tool Wear and evaluate machined surface quality in intermittent cutting process.

S T Dundur - One of the best experts on this subject based on the ideXlab platform.

  • Finite Element Simulation to study the effect of Flank Wear Land inclination on Cutting forces and temperature distribution in orthogonal machining
    The Journal of Engineering and Fundamentals, 2014
    Co-Authors: Vishaldatt V Kohir, S T Dundur
    Abstract:

    Flank Wear greatly influences the economics of the cutting operations as it is related to the prediction of tool life of the cutting tool. The initial geometry of the tool alters with progress of the Flank Wear. It has been experimentally proved that Flank Wear Land is not parallel to the cutting direction. This paper investigates the effect of length and inclination of the Flank Wear Land on the cutting forces, effective stress and temperature distribution using finite element simulations. Finite element modeling is preferred in the present investigation, as it consumes less time and cost compare to empirical or analytical modeling and capable of providing information about the distribution of performance measures. DEFORM 2D, a widely used software tool employed for modeling and simulating the orthogonal machining process with different levels of Wear lengths and inclinations. The results of the study shows that, the Flank Wear Land inclination has higher influence on the thrust force compare to Wear Land length. The length and inclination of Flank Wear Land effects the maximum temperature in tool.

  • influence of Flank Wear Land inclination on attributes of orthogonal machining using slip line field
    2014
    Co-Authors: Vishaldatt V Kohir, S T Dundur
    Abstract:

    Progressive tool Wear alters the micro geometry of the cutting tool. Of all the tool Wear types, Flank Wear attracted maximum attention as it is often used for determining the tool life. Many researchers agreed to the presence of nonzero inclination of Flank Wear Land with respect to cutting direction but, no research available provides the effect of Flank Wear Land inclination on the attributes of the orthogonal machining. Hence this paper is targeted to investigate the influence of Flank Wear Land inclination angle on orthogonal machining using slip line field model. The investigation verifies the influence of non-zero inclination of Flank Wear Land inclination on the attributes of the orthogonal machining.