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Devotta, A. M., Sivaprasad, P. V., Beno, T., Eynian, M., Hurtig, K., Magnevall, M. & Lundblad, M. (2019). A modified Johnson-Cook model for ferritic-pearlitic steel in dynamic strain aging regime. Metals, 9(5)
Open this publication in new window or tab >>A modified Johnson-Cook model for ferritic-pearlitic steel in dynamic strain aging regime
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2019 (English)In: Metals, ISSN 2075-4701, Vol. 9, no 5Article in journal (Refereed) Published
Abstract [en]

In this study, the flow stress behavior of ferritic-pearlitic steel (C45E steel) is investigated through isothermal compression testing at different strain rates (1 s-1, 5 s-1, and 60 s-1) and temperatures ranging from 200 to 700 °C. The stress-strain curves obtained from experimental testing were post-processed to obtain true stress-true plastic strain curves. To fit the experimental data to well-known material models, Johnson-Cook (J-C) model was investigated and found to have a poor fit. Analysis of the flow stress as a function of temperature and strain rate showed that among other deformation mechanisms dynamic strain aging mechanism was active between the temperature range 200 and 400 °C for varying strain rates and J-C model is unable to capture this phenomenon. This lead to the need to modify the J-C model for the material under investigation. Therefore, the original J-C model parameters A, B and n are modified using the polynomial equation to capture its dependence on temperature and strain rate. The results show the ability of the modified J-C model to describe the flow behavior satisfactorily while dynamic strain aging was operative. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

Place, publisher, year, edition, pages
MDPI AG, 2019
Keywords
flow stress; modified Johnson-Cook model; dynamic strain aging
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13989 (URN)10.3390/met9050528 (DOI)2-s2.0-85066741813 (Scopus ID)
Funder
Swedish Research Council, 20110263, 20140130
Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-07-25Bibliographically approved
Agic, A., Eynian, M., Ståhl, J.-E. -. & Beno, T. (2019). Dynamic effects on cutting forces with highly positive versus highly negative cutting edge geometries. International Journal on Interactive Design and Manufacturing
Open this publication in new window or tab >>Dynamic effects on cutting forces with highly positive versus highly negative cutting edge geometries
2019 (English)In: International Journal on Interactive Design and Manufacturing, ISSN 1955-2513, E-ISSN 1955-2505Article in journal (Refereed) Epub ahead of print
Abstract [en]

Understanding the influence of the cutting edge geometry on the development of cutting forces during the milling process is of high importance in order to predict the mechanical loads on the cutting edge as well as the dynamic behavior on the milling tool. The work conducted in this study involves the force development over the entire engagement of a flute in milling, from peak force during the entry phase until the exit phase. The results show a significant difference in the behavior of the cutting process for a highly positive versus a highly negative cutting edge geometry. The negative edge geometry gives rise to larger force magnitudes and very similar developments of the tangential and radial cutting force. The positive cutting edge geometry produces considerably different developments of the tangential and radial cutting force. In case of positive cutting edge geometry, the radial cutting force increases while the uncut chip thickness decreases directly after the entry phase; reaching the peak value after a certain delay. The radial force fluctuation is significantly higher for the positive cutting edge geometry. The understanding of such behavior is important for modelling of the milling process, the design of the cutting edge and the interactive design of digital applications for the selection of the cutting parameters.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Milling, Cutting force, Cutting edge geometry, Frequency spectrum, RMS
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-13302 (URN)10.1007/s12008-018-0513-5 (DOI)
Funder
Knowledge Foundation
Note

First Online: 11 December 2018

Funders: Seco Tools

Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-03-05Bibliographically approved
Agic, A., Eynian, M., Ståhl, J.-E. -. & Beno, T. (2019). Experimental analysis of cutting edge effects on vibrations in end milling. CIRP - Journal of Manufacturing Science and Technology, 24, 66-74
Open this publication in new window or tab >>Experimental analysis of cutting edge effects on vibrations in end milling
2019 (English)In: CIRP - Journal of Manufacturing Science and Technology, ISSN 1755-5817, E-ISSN 1878-0016, Vol. 24, p. 66-74Article in journal (Refereed) Published
Abstract [en]

The ability to minimize vibrations in milling by the selection of cutting edge geometry and appropriate cutting conditions is an important asset in the optimization of the cutting process. This paper presents a measurement method and a signal processing technique to characterize and quantify the magnitude of the vibrations in an end milling application. Developed methods are then used to investigate the effects of various cutting edge geometries on vibrations in end milling. The experiments are carried out with five cutting edge geometries that are frequently used in machining industry for a wide range of milling applications. The results show that a modest protection chamfer combined with a relatively high rake angle has, for the most of cutting conditions, a reducing effect on vibration magnitudes. Furthermore, dynamics of a highly positive versus a highly negative cutting geometry is explored in time domain and its dependency on cutting conditions is presented. The results give concrete indications about the most optimal cutting edge geometry and cutting conditions in terms of dynamic behavior of the tool.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Milling, Acceleration, Cutting edge, Frequency spectrum, Rake angle, Chamfer
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-13735 (URN)10.1016/j.cirpj.2018.11.001 (DOI)000460558000007 ()
Funder
Knowledge Foundation
Note

Funders: Seco Tools

Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-04-04Bibliographically approved
Eynian, M. (2019). In-process identification of modal parameters using dimensionless relationships in milling chatter. International journal of machine tools & manufacture, 143, 49-62
Open this publication in new window or tab >>In-process identification of modal parameters using dimensionless relationships in milling chatter
2019 (English)In: International journal of machine tools & manufacture, ISSN 0890-6955, E-ISSN 1879-2170, Vol. 143, p. 49-62Article in journal (Refereed) Published
Abstract [en]

Machining parameters needed for stable, high-performance high-speed machining could be found using mathematical models that need accurate measurements of modal parameters of the machining system. In-process modal parameters, however, can slightly differ from those measured offline and this can limit the applicability of simple measurement methods such as impact hammer tests. To study and extract the in-process modal parameters, mathematical models are used to define two key dimensionless parameters and establish their relationships with each other and the modal parameters. Based on these relationships, the modal parameters are extracted using two analytical methods, the two-point method (TPM), and the regression method (RM). As shown with experimental studies, the RM extracts the modal parameters successfully and while being much faster than the existing iteration-based methods, it provides stability lobe predictions that match well the experimental results. Furthermore, it is noted that the natural frequency parameter is estimated with much better relative precision compared to the damping ratio and the modal stiffness parameters. © 2019 Elsevier Ltd

Keywords
Composite beams and girders, Identification (control systems), Iterative methods, Milling (machining), Modal analysis, Regression analysis, Accurate measurement, Chatter, Dimensionless parameters, Frequency parameters, High speed machining, In-process, Machining dynamics, Stability lobe diagrams, Parameter estimation
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13988 (URN)10.1016/j.ijmachtools.2019.04.003 (DOI)2-s2.0-85066478846 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-07-25Bibliographically approved
Eynian, M., Magnevall, M., Cedergren, S., Wretland, A. & Lundblad, M. (2018). New methods for in-process identification of modal parameters in milling. Paper presented at 8th CIRP Conference on High Performance Cutting, HPC 2018; Budapest; Hungary; 25 June 2018 through 27 June 2018. Procedia CIRP, 77, 469-472
Open this publication in new window or tab >>New methods for in-process identification of modal parameters in milling
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2018 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 77, p. 469-472Article in journal (Refereed) Published
Abstract [en]

Chatter vibrations encountered in machining can degrade surface finish and damage the machining hardware. Since chatter originates from unstable interaction of the machining process and the machining structure, information about vibration parameters of the machining structure should be used to predict combinations of cutting parameters that allow stable machining. While modal test methods, for example those with impact hammers, are widely used to identify structural parameters; the need for sophisticated test equipment is prohibitive in their use. Furthermore, dynamic properties of critical components of a machine tool may change as they get affected by cutting loads, material removal and spindle rotation. Recently few algorithms have been proposed that identify the in-process dynamic parameters by frequency measurements, thus avoiding these problems. In this paper, some of these algorithms are reviewed and their capabilities and limitations in processing am experimental data set are compared and discussed. © 2018 The Authors. Published by Elsevier Ltd.

Keywords
Data handling; Equipment testing; Machine components; Machine tools; Milling (machining); Modal analysis, Chatter; Chatter vibrations; Critical component; Cutting parameters; Frequency measurements; In-process; Structural parameter; Vibration parameters, Parameter estimation
National Category
Applied Mechanics Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-13202 (URN)10.1016/j.procir.2018.08.269 (DOI)2-s2.0-85057398424 (Scopus ID)
Conference
8th CIRP Conference on High Performance Cutting, HPC 2018; Budapest; Hungary; 25 June 2018 through 27 June 2018
Funder
Knowledge Foundation
Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2019-05-24Bibliographically approved
Eynian, M., Das, K. & Wretland, A. (2017). Effect of tool wear on quality in drilling of titaniumalloy Ti6Al4V, Part I: Cutting Forces, BurrFormation, Surface Quality and Defects. High speed machining, 3, 1-10
Open this publication in new window or tab >>Effect of tool wear on quality in drilling of titaniumalloy Ti6Al4V, Part I: Cutting Forces, BurrFormation, Surface Quality and Defects
2017 (English)In: High speed machining, E-ISSN 2299-3975, Vol. 3, p. 1-10Article in journal (Refereed) Published
Abstract [en]

Titanium's Ti6Al4V, alloy is an important material with a wide range of applications in the aerospace industry.Due to its high strength, machining this material for desired quality at high material removal rate is challenging and may lead to high tool wear rate. As a result,this material may be machined with worn tools and the effects of tool wear on machining quality need to be investigated.In this experimental paper, it is shown how drills of various wear levels affect the cutting forces, surface quality and burr formation. Furthermore, it is shown that high cutting forces and high plastic deformation, along with high temperatures that arise in cutting with worn tools may lead to initiation of microscopic cracks in the workpiece material in proximity of the drilling zone.

Place, publisher, year, edition, pages
Warsaw, Poland: De Gruyter Open, 2017
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11875 (URN)10.1515/hsm-2017-0001 (DOI)
Available from: 2017-12-04 Created: 2017-12-04 Last updated: 2019-05-23Bibliographically approved
Das, K., Eynian, M. & Wretland, A. (2017). Effect of tool wear on quality in drilling of titaniumalloy Ti6Al4V, Part II: Microstructure and Microhardness. High speed machining, 3, 11-22
Open this publication in new window or tab >>Effect of tool wear on quality in drilling of titaniumalloy Ti6Al4V, Part II: Microstructure and Microhardness
2017 (English)In: High speed machining, E-ISSN 2299-3975, Vol. 3, p. 11-22Article in journal (Refereed) Published
Abstract [en]

Drilling of Ti6Al4V with worn tools can introduce superficial and easily measured features such as increase of cutting forces, entry and exit burrs and surface quality issues and defects. Such issues were presented in the part I of this paper. In part II, subsurface quality alterations,such as changes of the microstructure and microhardness variation is considered by preparing metallographic sections and measurement, mapping of the depth of grain deformation, and microhardness in these sections. Drastic changes in the microstructure and microhardness were found in sections drilled with drills with large wear lands,particularly in the dry cutting tests. These measurements emphasize the importance of detection of tool wear and ensuring coolant flow in drilling of holes in titanium components.

Place, publisher, year, edition, pages
Warsaw, Poland: De Gruyter Open, 2017
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11876 (URN)10.1515/hsm-2017-0002 (DOI)
Available from: 2017-12-04 Created: 2017-12-04 Last updated: 2018-06-18Bibliographically approved
Devotta, A. M., Beno, T., Siriki, R., Löf, R. & Eynian, M. (2017). Finite Element Modeling and Validation of Chip Segmentation in Machining of AISI 1045 Steel. Paper presented at Conference of 16th CIRP Conference on Modelling of Machining Operations, CIRP CMMO 2017 ; Conference Date: 15 June 2017 Through 16 June 2017. Procedia CIRP, 58, 499-504
Open this publication in new window or tab >>Finite Element Modeling and Validation of Chip Segmentation in Machining of AISI 1045 Steel
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2017 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 58, p. 499-504Article in journal (Refereed) Published
Abstract [en]

The finite element (FE) method based modeling of chip formation in machining provides the ability to predict output parameters like cutting forces and chip geometry. One of the important characteristics of chip morphology is chip segmentation. Majority of the literature within chip segmentation show cutting speed (vc) and feed rate (f) as the most influencing input parameters. The role of tool rake angle (α) on chip segmentation is limited and hence, the present study is aimed at understanding it. In addition, stress triaxiality’s importance in damage model employed in FE method in capturing the influence of α on chip morphology transformation is also studied. Furthermore, microstructure characterization of chips was carried out using a scanning electron microscope (SEM) to understand the chip formation process for certain cutting conditions. The results show that the tool α influences chip segmentation phenomena and that the incorporation of a stress triaxiality factor in damage models is required to be able to predict the influence of the α. The variation of chip segmentation frequency with f is predicted qualitatively but the accuracy of prediction needs improvement. © 2017 The Authors.

Keywords
Cutting; Forecasting; Machining centers; Scanning electron microscopy; Shear stress, Chip morphologies; Chip segmentation; Cutting conditions; Damage model; Microstructure characterization; Output parameters; Stress triaxiality; Stress triaxiality factor, Finite element method
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11909 (URN)10.1016/j.procir.2017.03.259 (DOI)2-s2.0-85029738278 (Scopus ID)
Conference
Conference of 16th CIRP Conference on Modelling of Machining Operations, CIRP CMMO 2017 ; Conference Date: 15 June 2017 Through 16 June 2017
Funder
Knowledge Foundation, 20110263, 20140130.
Note

Funders: Sandvik Coromant

Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2019-05-21Bibliographically approved
Agic, A., Eynian, M., Hägglund, S., Ståhl, J.-E. & Beno, T. (2017). Influence of radial depth of cut on entry conditions and dynamics in face milling application. Journal of Superhard Materials, 39(4), 259-270
Open this publication in new window or tab >>Influence of radial depth of cut on entry conditions and dynamics in face milling application
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2017 (English)In: Journal of Superhard Materials, ISSN 1063-4576, Vol. 39, no 4, p. 259-270Article in journal (Refereed) Published
Abstract [en]

The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavorable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. Under some circumstances the radial depth of cut in combination with milling cutter geometry might give unfavorable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon is originated from the geometrical features that affect the rise time of the cutting edge engagement into workpiece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult-to-cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the workpiece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behavior is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using the root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.

Place, publisher, year, edition, pages
New York: Allerton Press, 2017
Keywords
milling entry, radial depth, cutting edge, cutting force, vibration
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-11769 (URN)10.3103/S1063457617040062 (DOI)000409936100006 ()2-s2.0-85029210912 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2017-10-20 Created: 2017-10-20 Last updated: 2019-05-23Bibliographically approved
Parsian, A., Magnevall, M., Beno, T. & Eynian, M. (2017). Sound Analysis in Drilling, Frequency and Time Domains. Paper presented at 16th CIRP Conference on Modelling of Machining Operations, CIRP CMMO 2017; Cluny; France; 15 June 2017 through 16 June 2017. Procedia CIRP, 58, 411-415
Open this publication in new window or tab >>Sound Analysis in Drilling, Frequency and Time Domains
2017 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 58, p. 411-415Article in journal (Refereed) Published
Abstract [en]

This paper proposes a guideline for interpreting frequency content and time history of sound measurements in metal drilling processes. Different dynamic phenomena are reflected in generated sound in cutting processes. The footprint of such phenomena including torsional, lateral regenerative chatter and whirling in sound measurement results are discussed. Different indexable insert drills, at several cutting conditions, are covered. The proposed analysis could be used for studying, online monitoring and controlling of drilling processes. © 2017 The Authors.

Keywords
Acoustic variables measurement; Architectural acoustics; Drilling; Machining centers; Vibration analysis, Chatter; Cutting conditions; Frequency and time domains; Frequency contents; Indexable inserts; Regenerative chatters; Sound analysis; Vibrations, Time domain analysis
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-11907 (URN)10.1016/j.procir.2017.03.242 (DOI)2-s2.0-85029768891 (Scopus ID)
Conference
16th CIRP Conference on Modelling of Machining Operations, CIRP CMMO 2017; Cluny; France; 15 June 2017 through 16 June 2017
Funder
Knowledge Foundation
Note

Available online 31 May 2017

Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2019-05-21Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9331-7354

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