Papers

C.011
Post Date: March 22, 2018
Response Deadline: April 22, 2018
Publication:

Evaluation of the Superabsorbent Coolant as a New Approach to Semi-Dry Machining

Authors: Yousef Shokoohi, José Mario Paiva, German Fox-Rabinovich,
Carlos Alberto Schuch Bork, Stephen Clarence Veldhuis

AbstractThis work presents a novel coolant suitable for different machining processes. The focus of this study is  applying superabsorbent Coolant (SAC) during milling of hardened H13 steel and evaluating the possibility of utilizing superabsorbent material as a coolant. The use of SAC is a novel method of semi-dry machining that proves the performance of hydrogels as a coolant and opens a new window for industrial applications. The results of machining studies indicate that SAC can considerably reduce cutting force, improve surface roughness and also increase tool life.

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J.020
Post Date: March 9, 2018
Response Deadline: April 9, 2018
Publication:

A feedrate scheduling algorithm to constrain tool tip position and tool
orientation errors of five-axis CNC machining under cutting load disturbances

Authors: Jixiang Yang, Deniz Aslan, Yusuf Altintas

AbstractThe cutting forces are transmitted to feed drives as the main disturbances to machine tool controllers which lead to tool tip position and tool axis orientation tracking errors along multi-axis tool paths. Unless avoided, excessive tracking errors are passed as dimensional form errors on the part surface and violate the acceptable tolerance limits. This paper proposes a model
to keep the Computer Numerical Control (CNC) induced errors within the desired tolerance limit by scheduling the feed along the five axis tool paths. The cutting forces at the tool tip are transmitted to three translational and two rotary servo drives of the machine tool using its kinematic model. Tracking errors of each axis contributed by cutting forces are modeled using the disturbance transfer function of servo drives. The tracking errors are mapped to the workpiece coordinate system to evaluate the tool tip position and tool axis orientation errors at discrete tool path locations. The cutting forces, therefore the tracking errors, are modeled as a linear function of tangential feed velocity. The feed is adjusted to constrain the tool tip position and tool axis orientation errors at the desired tolerance levels along the tool path. The proposed algorithm has been experimentally validated by milling a curved tool path on a five-axis commercial CNC machine tool. It is shown that the proposed algorithm can significantly
improve the part machining accuracy without increasing the machining time.

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J.019
Post Date: March 9, 2018
Response Deadline: April 9, 2018
Publication:

Geometric error compensation with a 6 degree of
freedom rotary magnetic actuator

Authors: Alexander Yuen, Yusuf Altintas

Abstract – This paper presents a methodology to compensate the tooltip position errors caused by the geometric errors of a 3-axis gantry type microm ill integrated with a 6 degree of freedom rotary magnetic table. A geometric erro r free ideal forward kinematic model of the 9 axis machine has been developed, using homogenous transformation matrices. The geometric errors of each line axis, which include one positioning, two straightness, pitch, roll and yaw errors, are measured with a laser interferometer and fit to quintic polynomial functions in the working volume of the machine. The forward kinematic model is modified to include the
geometric errors which, when subtracted from the ideal kinematic model, gives the deviation between the desired tooltip position with and without geometric errors. The position commands of the 6 degree of freedom rotary magnetic table are modified in real time to compensate for the tooltip deviation using a gradient descent algorithm. The algorithm is simulated and verified experimentally on the 9 axis micromill controlled by an in-house developed Virtual/Real Time Open CNC system.

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J.018
Post Date: March 9, 2018
Response Deadline: April 9, 2018
Publication:

Dynamics and Stability of TurnMilling Operations with
Varying 
Time Delay in Discrete Time Domain

Authors: Alptunc Comak, Yusuf Altintas

Abstract – Turn- milling machines are widely used in industry because of their multi- functional capabilities in producing complex parts in one set-up. Both milling cutter and workpiece rotate simultaneously while the machine travels in three Cartesian directions leading to five axis kinematics with complex chip generation mechanism. This paper presents a general mathematical model to predict the chip thickness, cutting force and chatter stability of turn milling operations. The dynamic chip thickness is modeled by considering the rigid body motion, relative vibrations between the tool and workpiece, and cutter – workpiece engagement geometry. The dynamics of the process are governed by delayed differential equations by time periodic coefficients with a time varying delay contributed by two simultaneously rotating spindles and kinematics of the machine. The stability of the system has been solved in semi-discrete time domain as a function of depth of cut, feed, tool spindle speed and workpiece speed. The stability model has been experimentally verified in turn milling of Aluminum alloy cut with a helical cylindrical end mill.

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J.017
Post Date: March 9, 2018
Response Deadline: April 9, 2018
Publication:

Virtual compensation of deflection errors in ball end milling of flexible blades

Authors:  Yusuf Altintas, O. Tuysuz, M. Habibi, Z.L. Li

Abstract – The deflections of highly flexible turbine blades and slender end mills lead to tolerance violations during milling. This paper presents a digital simulation and compensation model for blade machining operations. Stiffness of the blade at the cutting zone is updated as the metal is removed without re-meshingusing a computationally efficient sub-structuring technique. The cutter-workpiece engagement isevaluated by considering the deformations of both end mill and the blade under the cutting loads. The estimated deformations are compensated by modifying the tool path coordinates. The model has been experimentally verified in ball-end milling of a blade whose dimensional errors have been reduced from ~70 μmto ~10μm.

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J.016
Post Date: March 9, 2018
Response Deadline: April 9, 2018
Publication:

On-line chatter detection in milling using drive motor current commands extracted from CNC

Authors: Jixiang Yang, Deniz Aslan, Yusuf Altintas

Abstract – This paper presents an on-line chatter detection method in milling using drive motor current commands supplied by the CNC system in real-time. The methodology is described by using the spindle drive motor current command although it has been applied to the feed drives as well which is demonstrated in the results section. The transfer function of spindle velocity controller is constructed by reading the control law parameters and measuring the Frequency Response Function (FRF) of the system automatically using an external computer communicating with the CNC in real time. By subtracting the rigid body based FRF from the measured FRF of the velocity controller that includes the flexibilities, the structural modes of the spindle drive are identified. The closed loop transfer function between the cutting torque at the tool and corresponding noise free digital current commanded by the CNC is formed. The effects of structural dynamic modes of the spindle are compensated via a proposed observer. The bandwidth of the compensated FRF of the current command over cutting torque disturbance has been increased to 2.5 k Hz with 10kHz communication speed limit of the CNC with external PC. After removing the forced vibration components, the frequency and presence of chatter are detected from the Fourier Spectrum of the current commands supplied by CNC in real time. The proposed system is experimentally validated in milling tests.

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J.015
Post Date: March 9, 2018
Response Deadline: April 9, 2018
Publication:

On-Line Energy Based Milling Chatter Detection

Authors: Hakan Caliskan, Zekai Murat Kilic, Yusuf Altintas

Abstract – Milling exhibits forced vibrations at tooth passing frequency and its harmonics, as well as chatter vibrations close to one of the natural modes. In addition, there are sidebands which spread at the multiples of tooth passing frequency above and below the chatter frequency, which make the robust chatter detection difficult. This paper presents a novel on-line chatter detection method by monitoring vibration energy. Forced vibrations are removed from the measurements in discrete time domain using a Kalman filter. After removing all periodic components, the amplitude and frequency of chatter are searched in between each tooth passing frequency harmonics using a non- linear energy operator. When the energy of any chatter component grows relative to the energy of forced vibrations, the presence of chatter is detected. The proposed method works in discrete real time intervals, and can detect the chatter earlier than computationally costly frequency domain based methods which rely on Fast Fourier Transforms. The method has been experimentally validated in several milling tests using both microphone and accelerometer measurements.

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J.014
Post Date: November 17, 2017
Response Deadline: Released
Publication:

Identi cation of Workpiece Location on Rotary Tables to Minimize
Tracking Errors in Five-Axes Machining

Authors: Jixiang Yang, Deniz Aslan, Yusuf Altintas

Abstract – Five-axis CNC machine tools are widely used in machining parts with free form surfaces. This paper presents optimal placement of parts on the ve-axis machine tool tables to minimize the tracking errors of the rotary servo drives. The cutting forces along the tool path are first simulated at the workpiece coordinate system in Computer-Aided-Manufacture (CAM) environment. The cutting torques transmitted to the rotary and translational drives are predicted using the location of the part on the table and kinematic con guration of the machine tool. The optimal location of the part on the table is identifi ed by minimizing the forces transmitted to the rotary drives as torque disturbances. The proposed model has been experimentally validated on a ve-axis machine with tilt-table con guration. It has been shown that the tracking and contouring errors can be signi ficantly reduced with the proposed strategy, which can be used by process planners in digital simulation environment.

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J.013
Post Date: November 17, 2017
Response Deadline: Released
Publication:

Mechanics and dynamics of orbital drilling operations

Authors:  Onur Mert Ozturk, Zekai Murat Kilic, Ph.D., Yusuf Altintas

Abstract –  This paper presents modeling the mechanics and dynamics of the orbital drilling process to predict the cutting forces and chatter stability. The tool-workpiece engagement along the tool path is identified and used in predicting the chip thickness and cutting contributed by the periphery and bottom edges of the tool are predicted. Dynamics of the system have been modeled, and the machining stability is solved in discrete-time and frequency domains. Three dimensional stability lobes are predicted as a function of tool position along the orbital path, spindle speed and pitch length of the orbital path. The mechanics, stability and surface location error models have been experimentally validated by conducting orbital drilling of holes. The mathematical model is intended for optimal selection of tool geometry, orbital and tangential feeds, and spindle speeds without causing chatter, violating dimensional tolerances and overloading of the machine.

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J.012
Post Date: November 17, 2017
Response Deadline: Released
Publication:

Generalized Dynamics and Stability of Turn-Milling Operations in Discrete Time Domain

Authors: Alptunc Comak, Yusuf Altintas

Abstract – Turn-milling machines are widely used in industry because of their multi-functional capabilities in producing complex parts in one set-up. Both milling cutter and workpiece rotate simultaneously while the machine travels in three Cartesian directions leading to five axis kinematics with complex chip generation mechanism. This paper presents a general mathematical model of turn milling dynamics to predict the chip thickness, cutting force and chatter stability of turn milling operations. The dynamic chip thickness is modeled by considering the rigid body motion, relative vibrations between the tool and workpiece, and cutter-workpiece engagement geometry. The dynamic model has time periodic coefficients with a time varying delay contributed by two simultaneously rotating spindles and kinematics of the machine. The resulting time varying delayed differential equations are formulated and the stability of the system is solved in semi-discrete time domain as a function of depth of cut, tool spindle speed and workpiece speed. The stability model has been experimentally verified in turn milling of Aluminum alloy with a helical cylindrical end mill.

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J.011
Post Date: November 17, 2017
Response Deadline: Released
Publication:

Prediction of Cutting Forces in 5-axis Milling Using Feed Drive Current Measurements

Authors: D. Aslan, Member, IEEE, Y. Altintas*, Fellow, ASME

Abstract This paper presents a model to identify cutting forces from feed drive current measurements in 5-axis milling processes. The friction, equivalent inertia and the Frequency Response Function (FRF) of the structural disturbance of three translational (X-Y-Z) and two rotational (A-C) drives are identified. The disturbances caused by the structural modes are compensated through disturbance Kalman Filters for each drive. The kinematics of the 5-axis CNC is modeled using the Denavit-Hartenberg (D-H) method and compensated motor current on the drives are transformed to the tool coordinate frame to obtain cutting forces. The application of the proposed method is demonstrated experimentally by machining a 5-axis part on a Quaser UX600 machining center. LSV-2 communication protocol is used to collect commanded, noise free digital motor currents, drive speeds, tool center point position, tool orientation, spindle speed and tangential velocity from CNC via Ethernet connection.

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J.010
Post Date: November 10, 2017
Response Deadline: Released
Publication:

Cutting performance of low stress thick TiAlN coatings deposited by
new AIP cathode during machining of compacted graphite cast iron (CGI)

Authors: K. Yamamoto, M. Abdoos, J. M. Paiva, P. Stolf, B. Beake, R. Sushant, G. Fox-Rabinovich, S. Veldhuis

Abstract – A method of PVD coating deposition, using so-called ‘superfine cathode (SFC)’ is presented, which allows to produce hard PVD coatings as thick as 15 microns and above. In some applications such coatings have showed better tool life as compared to the conventional PVD coatings with lower thicknss of the range of up to 5 microns. One of such examples is the machining of compacted graphite iron (CGI). CGI belongs to the category of difficult to cut materials. This is due to quite intensive buildup edge formation during machining of this material. Finite element modeling of the tempratgure/stress profiles was made for the coatings with different thickness of 5, 10, 15 microns. Comprehensive charactrization of the coating characteristics was performed using XRD stuructual evaluation, TEM, SEM/EDS studies, nano-hardness and nono-impact measurements, residual stress measurements. New family of PVD coatings deposited by SFC technique combines smooth surface, the hardness, typical for this category of coatings, low residual stresses and elevated fracture toughness. Application of the coating with this set of characteristics allows to diminish the intensity build up edge formation during machining of CGI (turning operations). Optimization of the TiAlN-based coatings composition (Ti/Al ratio), architecture (mono vs. multilayer) and thickness were performed. Application of the optimized coating resulted in the cutting tool life improvement under both finishing and roughing turing of CGI by 40-60 %.

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J.009
Post Date: November 3, 2017
Response Deadline: Released
Publication:

Analysis of the Mechanisms of the Built-up Edge Formation during turning of Super Duplex Stainless Steel

Authors: Yassmin Seid Ahmed, German Fox-Rabinovich, Bipasha Bose, Danielle Cavelli,
Goulnara Dosbaeva and Stephen Clarence Veldhuis

Abstract – Tool wear is a very important factor determining tool life and surface integrity of a machined surface, hence, it is necessary to minimize tool wear to maximize tool life and to optimize the manufacturing performance. Different mechanisms can cause the tool wear in a specific machining process, first of all adhesion onto the cutting tool frequently observed during machining of super duplex stainless steels (SDSS), generating damage on the tool rake face. Adhesion of the workpiece material causing built-up edge (BUE) formation tends to promote tool chipping, since BUE is unstable structure, but it periodically breaks off leading to tool failure. The phenomenon of BUE formation can lead to poor machined surface texture and accelerated tool wear, subsequently leading to increased manufacturing costs. An experimental study was undertaken in order to study the mechanisms of BUE formation during cutting process. In this paper, the mechanisms that trigger the formation of BUE during the machining of super duplex stainless steel (SDSS) alloys—Grade UNS S32750 with PVD TiAlN/TiSiN coated carbide tool has been investigated. The process parameters were chosen so that the BUE formation was provoked. The BUE formation and tool wear was evaluated throughout the cutting test using an Alicona Infinite Focus microscope and a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). Tribo-film formation on the worn rake surface of the tool was analyzed using X-ray Photoelectron Spectroscopy (XPS). Comprehensive characterization of the BUE mechanisms of PVD TiAlN/TiSiN coated vs. uncoated cutting tool wear was performed using electron backscatter diffraction (EBSD) and nano-indentation test. This paper investigates the deformation mechanisms and plastic behavior of austenite and ferrite phases in BUE cross section. Nono-hardness distribution map and EBSD phase mapping of BUE cross section samples revealed a built-up of austenite bands are collected at the tool-chip interface and ferrite bands collected on the top. Moreover, SEM images of BUE cross section samples show micro-cracks in the region of austenite.

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J.008
Post Date: July 12, 2017
Response Deadline: Released
Publication:

Virtual Model of Gear Shaping Part II: Elastic Deformations and Virtual Gear Metrology

Authors: Andrew Katz, Kaan Erkorkmaz*, and Fathy Ismail

Abstract – Elastic deflection of cutting tools relative to the workpiece is one of the major factors contributing to dimensional part inaccuracies in machining. This paper examines the effect of tool deflection in gear shaping and its effect on the gear’s profile form error, which can cause transmission error and noise during gear operation. To simulate elastic tool deflection in gear shaping, the tool’s static stiffness is estimated from impact hammer testing. Then, based on simulated cutter-workpiece engagement and predicted cutting forces, the elastic deflection of the tool is calculated at each time step. To examine the effect of tool deflection on the profile error of the gear, a virtual gear measurement module is developed and used to predict the involute profile deviations in the virtually machined part. Simulated and measured profile deviations were compared for a one-pass external spur gear process and a two-pass external spur gear process. The simulated profile errors correlate very well with the measured profiles on the left flank of the workpiece, however additional research is needed to improve the accuracy of the model on the right flank.

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J.007
Post Date: July 12, 2017

Response Deadline: Released
Publication:

Virtual Model of Gear Shaping Part I: Kinematics, Cutter-Workpiece Engagement, and Cutting Forces

Authors: Andrew Katz, Kaan Erkorkmaz*, and Fathy Ismail

Abstract – Gear shaping is, currently, the most prominent method for machining internal gears, which are a major component in planetary gear boxes, however there are very few studies in the mechanics of the process. This paper presents a comprehensive model of gear shaping that includes the kinematics, cutter-workpiece engagement (CWE), and cutting forces. To predict the cutting forces, the CWE is calculated at discrete time steps using a tri-dexel discrete solid modeler. From the CWE in tri-dexel form, the two-dimensional chip geometry is reconstructed using Delaunay triangulation and alpha shape reconstruction which is then used to determine the undeformed chip geometry along the cutting edge. The cutting edge is discretized into nodes with varying cutting force directions (tangential, feed, and radial), inclination angle, and rake angle. If engaged in cutting during a time step, each node contributes an incremental force vector calculated with the oblique cutting force model. Using a 3-axis dynamometer on a Liebherr LSE500 gear shaping machine tool, the cutting force prediction algorithm was experimentally verified on a variety of processes and gears which included an internal spur gear, external spur gear, and external helical gear. The simulated and measured force profiles correlate closely with about 3-10% RMS error.

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J.006
Post Date: June 22, 2017
Response Deadline: Released
Publication:

Dynamics of Multi-point Thread Turning, PART II:
Threading Thin-walled Oil Pipes

Authors: M.R. Khoshdarregi, Y. Altintas*

Abstract –  Structural Dynamics of thin-walled cylindrical workpieces is dominated by their low-damped flexural modes. Due to the circumferential patterns of shell mode vibrations, the cutting forces result in different instantaneous displacements around the circumference of the workpiece. The residual shell vibrations can affect the chip thickness when the corresponding point arrives at the cutting region. This paper extends the general threading model developed in Part I to the case of thin-walled cylindrical shells. The circumference of the workpiece is discretized and the instantaneous displacements at each point due the cutting forces are evaluated. Dynamic equation of motion for threading thin-walled workpieces is derived, and the stability and surface location errors are investigated. The proposed stability model is validated experimentally on real scale oil pipes for different threading passes and different infeed values. Sample approaches for chatter suppression are demonstrated experimentally.

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J.005
Post Date: June 22, 2017
Response Deadline: Released
Publication:

Dynamics of Multi-point Thread Turning, PART I:
General Formulation

Authors: M.R. Khoshdarregi, Y. Altintas*

Abstract – This paper formulates the generalized dynamics and stability of thread turning operations with custom multi-point inserts. The closed loop chip regeneration mechanism is modeled by evaluating the effect of the current vibrations and the vibration marks left from the previous tooth. Using the developed chip discretization method, the dynamic cutting and process damping forces are obtained at each point along the cutting edge by projecting the three-dimensional vibrations of the tool and workpiece in the direction of local chip thickness. The equation of motion is derived in both physical and modal spaces, and stability is analyzed in frequency domain using Nyquist criterion. An iterative process optimization algorithm has been developed to maximize productivity while respecting machine tool’s torque and power limits.

Extension of the model to thin-walled workpieces along with the validating experiments on real scale oil pipes are presented in Part II of this article.

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J.004
Post Date: June 8, 2017
Response Deadline: Released
Publication:

Prediction of Cutting Forces in 5-axis Milling Using Feed Drive Current Measurements

Authors: D. Aslan, Y. Altintas*

Abstract This paper presents a model to identify cutting forces from feed drive current measurements in 5-axis milling processes. The friction, equivalent inertia and the Frequency Response Function (FRF) of the structural disturbance of three translational (X-Y-Z) and two rotational (C-A) drives are identified. The disturbances caused by the structural modes are compensated through extended Kalman Filters for each drive. The kinematics of the 5-axis CNC is modeled using the Denavit-Hartenberg (D-H) method and compensated forces on the drives are transformed to the tool coordinate frame to obtain cutting forces. The application of the proposed method is demonstrated experimentally by machining a 5-axis part on a Quaser UX600 machining center. LSV-2 communication protocol is used to collect commanded, noise free digital motor currents, drive speeds, tool center point position, tool orientation, spindle speed and tangential velocity from Heidenhain CNC via Ethernet connection.

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J.003
Post Date: April 27, 2017
Response Deadline: Released
Publication: Journal of Materials Processing TechnologyVolume 249, November 2017, Pages 96-107

Characterization and Micro End Milling of Graphene Nano Platelet and
Carbon Nanotube Filled Nanocomposites

Authors: M. Naresh, M. Mahmoodi, M. TabkhPaz, S.S. Park, X. Jin

Abstract Graphene and carbon nanotubes (CNTs) have been used in polymeric nanocomposites for improved mechanical, electrical, thermal and gas barrier properties. As the major applications of these relatively new materials are expected to be in the micro/meso-scale, their micro-machinability needs to be investigated. In this study, graphene nano platelet (GNP) and multi-walled carbon nanotube (MWCNT) filled polycarbonate (PC) nanocomposites were fabricated through injection molding. The molded nanocomposites were characterized for their thermal and mechanical properties. Micro mechanical machining was performed on the molded specimens to understand the material removal behavior. The micro cutting forces were measured and compared for the fabricated GNP and MWCNT filled nanocomposites. The experimental results showed that the GNP filled PC nanocomposites required higher cutting forces than plain PC. The chip morphologies of the materials were explored under scanning electron microscopy. Finite element modeling of machining PC and PC-GNP nanocomposites was conducted and the simulated cutting forces were compared with the experimental results. The results of this study show that the addition of GNP and MWCNT can significantly improve the dimensional accuracy and surface roughness of the machined surfaces.

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C.010
Post Date: March 1, 2017

Response Deadline: Released
Publication: 6th international Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Investigating the heavy-load, high-temperature friction behaviour of uncoated and PVD-coated WC-Co substrates in contact with SAE J434 D5506 ductile iron and AISI 1045 carbon steel

                    Authors: J.M. Boyd,  S.C. Veldhuis

Abstract— This paper contrasts the tribological behaviour of SAE J434 D5506 ductile iron and AISI 1045 carbon steel in contact with both uncoated and PVD-coated tungsten carbide, as tested on a custom heavy-load, high-temperature tribometer.  At temperatures above 300 °C, friction coefficient measurements as low as 0.10 were observed for uncoated carbide against ductile iron, which is lower than for any of the TiN-based PVD coatings tested.  At similar elevated temperatures, friction coefficient for uncoated carbide against the carbon steel rose dramatically.  An explanation is proposed for the unexpected friction behaviour of uncoated and PVD-coated carbide in contact with ductile iron.  Attempts at relating data obtained from tribometer tests to characteristics of machining processes with these tool and work materials is briefly discussed.

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C.009
Post Date: March 1, 2017

Response Deadline: Released
Publication: 6th international Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Cutting tool selection in machining based on
finite 
element simulation results

                    Authors: A. Emamian,  S.C. Veldhuis

Abstract— Cutting tool selection is an important part of developing a new cutting process. Tool geometry and tool coating are two variables which play an important role in tool performance and tool wear rate, and thereby in tool selection. The goal of this study is to develop a lagrangian FE model which has pretty long cutting length compare to other similar works to capture the behaviour of the AISI 1045 in contact with carbide tool, including chip formation, temperature and cutting forces profile in a steady-state condition. Temperature-dependent friction data was also used as an input data to be more precise in modeling. To realize this goal, ABAQUS 6.14 was used to obtain a coupled temperature-displacement model for thermal and mechanical analysis of orthogonal cutting. As the last step, the results of the model were compared with experiments.

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C.008
Post Date: March 1, 2017

Response Deadline: Released
Publication: 6th international Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

An Investigation of PVD Coatings on Cemented Carbide Cutting Tools
Using Advanced Nano-mechanical Test 
Methods

                    Authors: S. Chowdhury*, B. Bose*, B.D. Beake**,  G.S. Fox-Rabinovich**, S.C. Veldhuis*

Abstract— TiAlCrSiYN-based family of PVD hard coatings were specially designed for dry ultra-performance machining of hardened tool steels. However, there is a strong potential for further advances in the wear performance of the coatings through improvements in their architecture. Several different coating architectures (mono-layer, multilayer, bi-multilayer, bi-multilayer with optimized number of alternating nano-layers) were studied in relation to cutting tool life. The wear performance of the coatings was then co-related with mechanical and tribological properties namely hardness, elastic modulus, the ratio of the hardness to modulus (H/E), the resistance to plastic deformation (in terms of H3/E2), plasticity index (PI) defined as plastic work done during indentation divided by the total elastic and plastic work done during indentation, fatigue, impact, scratch and wear properties. Tool-life analysis showed that a significant increase in tool life could be achieved through optimization of the coatings architectures.

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C.007
Post Date: February 24, 2017
Response Deadline: Released
Publication: 6th international Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Machining of titanium alloys using surface engineered carbide cutting tools

                    Authors: M.S.I. Chowdhury, M. Aramesh, S.C. Veldhuis

Abstract— Titanium alloys are increasingly becoming the material of choice for a wide range of applications. They have received significant attention in various industries such as aerospace, biomedical and automotive due to their superior properties such as good strength-to-weight ratio, high corrosion resistance and bio-compatibility. However, machining of titanium alloys has proven to be difficult over the years owing to several inherent properties of these materials. Titanium has a very strong chemical affinity and, therefore, has a tendency to weld or stick to the cutting tool during machining that result in chipping and premature tool failure. Its low thermal conductivity causes high temperature at the tool/workpiece interface, affecting tool life adversely. Additionally, its high strength at elevated temperature and its low modulus of elasticity further impairs its machinability. Standard industrial practice for machining titanium alloys still involves the use of uncoated cemented carbide tools. Thereby with the aim to improve machinability of titanium alloys, current research investigated the effect of a variety of coatings on tool performance during Ti6Al4V machining. The coatings were selected based on their capability to form beneficial tribofilms. Tribofilms, which are generated as a result of self-adaptive characteristics of the coatings, could result in significant tool life improvements. Experimental studies revealed a promising coating that was able to significantly outperform uncoated cemented carbide tools. Detailed analysis of the coating showed formation of a beneficial tribofilm on the tool rake face, resulting in considerable reduction in tool wear values.

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C.006
Post Date: February 17, 2017

Response Deadline: Released
Publication: 6th international Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Study of tribofilms generation at different cutting speeds in
dry machining hardened AISI T1 and AISI D2 steel

                    Authors: J. Yuan, Y. Liu, S.K. Rawal, D. Covelli,  S.C. Veldhuis

Abstract—Hard dry machining of AISI T1 and AISI D2 steels at comparable hardness (58-60 HRC) were performed at 50 m/min, 80 m/min and 100 m/min cutting speeds separately with uncoated alumina ceramic tool inserts (Al2O3+TiC) in order to study the effect of cutting conditions on the generation of tribofilms. Comprehensive assessment of uncoated ceramic inserts in machining of T1 and D2 at different cutting speeds was made by tool maker microscope, Scanning Electron Microscope and X-ray Photoelectron Spectroscopy. It was observed that higher cutting speeds increased the formation of thermal protective and/or lubricating tribofilms. In machining D2 steel, more intensive formation of Cr-O tribo oxides resulted in lower wear rate; while machining T1 steel, a higher amount of W-O tribofilms generation provided better lubrication. At higher cutting speeds, wear/friction behaviour changes were attributed to differences in two factors: first, from a traditional micro-scale standpoint, the distribution of carbide within steels, the accumulation of thermal and mechanical damages during different cutting conditions and second, from a nano-scale viewpoint, the generation of protective/lubricating tribofilms due to change of machining conditions.

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C.005
Post Date: February 16, 2017

Response Deadline: Released
Publication: 6th international Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Controlling of tribofilm formation in dry machining of hardened AISI D2 steel
by tuning the cutting speeds

Authors: J. Yuan, Y. Liu, S. K. Rawal, D. Covelli, S.C. Veldhuis

Abstract— Hard turning of cold worked die steel AISI D2 was performed with uncoated mixed alumina inserts at various cutting speeds. The performance of the tool and formation of tribofilms were comprehensively characterized by generating a wear curve and performing SEM and XPS analysis on the tools operated under different cutting conditions. Based on our current understanding, the formation of tribofilms is enhanced by high temperatures brought on by higher cutting speeds with their beneficial properties impacting the wear and friction process.  In this research the tuning of the cutting speed was performed in order to generate favourable tribofilms and obtain an extended tool life. The results showed that the protective and lubricating tribofilms were formed; while during the tuning of cutting speeds, tribofilms generated at higher cutting speeds were not worn out at the same rate and were found to benefit the wear/friction process even when shifting to lower cutting speeds. This studying of tribofilms has offered new insight into our understanding of wear behaviour over a range of different cutting conditions and provides the manufacturing engineer with a novel approach to enhance the machining process.

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C.004
Post Date: February 16, 2017

Response Deadline: Released
Publication: 6th International Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

The study of wear performance and chip formation of coated carbide tools
during machining super duplex stainless steels

Authors: Y.S. Ahmed and S.C. Veldhuis

Abstract—  The paper presents the results of experimental studies during machining of UNS S32750 alloy by using uncoated and coated carbide inserts. Wear and failure mechanisms were investigated during turning operations and comprehensive analysis of the tool wear was performed using pictures of the worn regions taken using a scanning electronic microscopy (SEM) with energy dispersive spectroscopy (EDS). This analysis is fundamental to understand the root causes of tool wear. In addition, tribological performance evaluated through chip characteristics such as chip thickness, morphology of chip undersurface, chip micro-hardness, and chip microstructure. The results indicate that turning with a PVD deposited TiAlN coating on a carbide insert resulted in longer tool life, smaller chip thickness, and better chip under surface. The most frequent wear mechanism found during the tests were flank and notch wear, while the main tool wear mechanism was adhesion.

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C.003
Post Date: February 16, 2017

Response Deadline: Released
Publication: 6th International Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Compensation of Deflection-Induced Errors in High Precision Hard Turning
using a Piezoelectric-Based Fast Tool Servo

Authors: M.A. Shalaby, M.A. El Hakim, M.M. Adelhameed, S.C. Veldhuis

Abstract— This work presents an implementation of a piezoelectric-based fast tool servo (FTS) for compensation of deflection-induced errors in high precision hard turning.  Design procedures of FTS will be outlined in this paper. The expected errors due to the deflection of Machine-Fixture -Tool -Workpiece (MFTW) system during machining have been calculated. The effect of tool flank wear land width on the produced error has also been considered. Compensation of the calculated errors have been applied in the control strategy of the cutting tool expansion during cutting. High precision hard turning with the piezoelectric-based fast tool servo using different cutting variables has been carried out. A comparison between the applied technique and the grinding operation in terms of surface roughness has been established. Accuracy level in the range of IT5 and surface roughness in the range of 0.45 µm (Ra) can be achieved using this technique.

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C.002
Post Date: February 16, 2017

Response Deadline: Released
Publication: 6th International Conf on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Effect of some machining variables on surface roughness in precision turning

Authors: M.A. Shalaby, M.A. El Hakim, S.C. Veldhuis

Abstract— In precision turning, considerably small values of feed and depth of cut, which are usually lower than the tool nose radius, are used. The significantly small undeformed chip thickness which resulted from these values can deteriorate the machined surface. The present work incorporates experimental investigations of the effects of some machining variables (cutting speed, cutting tool material, feed, nose radius, and tool flank wear land width) on the measured surface roughness in precision turning of both annealed and hardened high speed steel (HSS). Annealed HSS resulted in relatively higher surface roughness than hardened HSS. Ceramic tools gave relatively lower surface roughness values than PCBN and CVD coated carbide tools.  This was attributed to their adaptive behavior exhibited under extreme conditions associated with machining hardened HSS. The proper choice of feed and tool nose radius results in considerably lower roughness values.

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C.001
Post Date: February 16, 2017
Response Deadline: Released
Publication: 6th International Conf. on Virtual Machining Process Technology (VMPT), Montreal, May 29-June 2, 2017

Investigation of tool life and tribofilm formation on
TiAlCrSiYN/TiAlCrN coated cemented carbide inserts during machining Inconel in dry-wet conditions

Authors: S. K. Rawal, J. Yuan, Y. Liu, G. S. Fox-Rabinovich, S. C. Veldhuis

Abstract— The Physical Vapor Deposition (PVD) technique was used to deposit nanostructured TiAlCrSiYN/TiAlCrN coatings on cemented carbide inserts. The aim of this research work is to investigate the performance of coated inserts in machining of Inconel 718 at various cutting speeds. The coated inserts were tested under two different conditions: dry machining for the first 200 meters of cutting length followed by machining with coolant until the end of tool life which was compared to machining with coolant all the way till the end of tool life. It was observed that an initial short run of wet machining with coolant and its continuous use until the end of tool life noticeably decreases tool wear. This is because the initial wet cutting conditions using coolant leads to the formation of protective/lubricious tribo-ceramic films and its subsequent use prevents total wearing out of the beneficial tribofilms that are forming. X-ray Photoelectron Spectroscopy, Scanning Electron Microscope, and Energy Dispersive X-Ray Spectroscopy were used to examine the wear of the coated inserts and tribofilm. The formation of protective tribofilm has been observed to increase tool life of the coated insert.

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J.002
Post Date: January 11, 2017
Response Deadline: Released
Publication: CIRP Annals, Volume 66, Issue 1, 2017, Pages 349-352

Integration of Virtual and On-Line Machining Process Control and Monitoring

Authors: Y. Altintas, D. Aslan

Abstract— This paper presents a virtually assisted on-line milling process control and monitoring system. A part machining process is simulated to predict the cutting forces, torque, power, chip load and other process states. The simulated machining states are accessed by a real time monitoring system which detects the tool failure and adaptively adjusts the feed by predicting the forces from the drive current. The integration of virtual simulation with real time measurements avoids false tool failure detection and transient overloads of the tools during adaptive control. The system is implemented on a CNC machining center. Cutting, Monitoring, Control

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J.001
Post Date: January 11, 2017

Response Deadline: Released
Publication: CIRP Annals, Volume 66, Issue 1, 2017, Pages 321-324

Dynamic Jamming in Dense Suspensions: Surface Finishing and Edge Honing Applications

Authors: J. Span, P. Koshy, F. Klocke, S. Muller, R. Coelho

Abstract— This paper presents the proof-of-concept of an innovative finish machining process wherein material is removed by abrasives suspended in a dense aqueous mixture of cornstarch, which serves as a smart finishing medium. Depending on the mode and rate at which said suspension is subject to strain, it transforms rapidly and reversibly, from being liquid-like, to a state that exhibits jamming-induced solid-like behaviour. This facilitates fine control over the level of mechanical interaction between the workpiece and the abrasives. The research clarifies fundamental process mechanics, and demonstrates the efficacy of exploiting this intriguing phenomenon in surface finishing and edge honing applications.

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