Wear behavior in turning high hardness alloy steel by CBN tool

Tool wear mechanisms in turning of high hardness alloy steels by CBN tools under various speeds are investigated by experimental studies. In low speed cutting, the binder of the hard particles of the cutting tool is found to be removed from the substrate due to a high cutting force, resulting from low cutting temperature, and abrasion dominates tool wear. When the cutting speed is increased, a protective layer resulting from the diffusion of the bond material of the cutting tool starts to form on the chip-tool interface. This layer works as a diffusion barrier. Hence, tool wear rate is reduced and the usable life of the CBN tool is prolonged. However, when the cutting speed is further increased, cutting temperature becomes the dominant factor instead of the cutting force. The high cutting speed causes inhomogeneous shear strain, and a transition from continuous chip to saw-tooth chip occurs. The friction force is found to increase because of the very irregular chip-tool contact. This would remove the protective layer. In addition, the bond between tool particles is weakened due to serious diffusion between the work material and the cutting tool under high cutting temperature. Subsequently, hard particles are detached, and tool life is reduced. Hence, it is concluded that there exists an optimal cutting speed of CBN tool in turning of high hardness alloy steels.

[1]  M. C. Shaw,et al.  Mechanics of Saw-Tooth Chip Formation in Metal Cutting , 1999 .

[2]  T. Ohtani,et al.  The effects of workpiece hardness on tool wear characteristics. Machining of cold work tool steel with CBN, ceramic and carbide tools , 1988 .

[3]  S. A. Klimenko,et al.  On the wear mechanism of cubic boron nitride base cutting tools , 1992 .

[4]  Gérard Poulachon,et al.  Wear behavior of CBN tools while turning various hardened steels , 2004 .

[5]  Gerry Byrne,et al.  Cutting tool wear in the machining of hardened steels , 2001 .

[6]  Cutting Performance of CBN Tools in Machining of Nickel Based Superalloy , 1992 .

[7]  Howard F. McMurdie,et al.  Phase diagrams for ceramists , 1964 .

[8]  Ross C. Purdy,et al.  The American Ceramic Society , 1922 .

[9]  P. K. Bossom.  Finish machining of hard ferrous workpieces , 1990 .

[10]  Athanasios G. Mamalis,et al.  Wear and Tool Life of CBN Cutting Tools , 2002 .

[11]  Y. K. Chou,et al.  Experimental investigation on CBN turning of hardened AISI 52100 steel , 2002 .

[12]  R. Recht.  Catastrophic Thermoplastic Shear , 1964 .

[13]  和久 茂,et al.  E.M.Levin, H.F.McMurdie: Phase Diagrams for Ceramists: The American Ceramic Society. 4055N. High St., Columbus 14, Ohio. Part I. 1956, 286頁, 20×27.5cm, $10, Part II, 1959, 153頁, 20×27.5cm, $8. , 1961 .

[14]  M. M. Barash,et al.  Cutting mechanism during machining of hardened steel , 1987 .

[15]  D. G. Flom,et al.  On the Catastrophic Shear Instability in High-Speed Machining of an AISI 4340 Steel , 1982 .

[16]  Yunn-Shiuan Liao,et al.  Wear characteristics in turning high hardness alloy steel by ceramic and CBN tools , 1999 .

[17]  Matthew A. Davies,et al.  On Chip Morphology, Tool Wear and Cutting Mechanics in Finish Hard Turning , 1996 .

[18]  M. C. Shaw.  Metal Cutting Principles , 1960 .

[19]  M. Lahres,et al.  Investigations of the wear of cubic boron nitride cutting tools using Auger electron spectroscopy and X-ray analysis by EPMA , 1997 .

[20]  M. Elbestawi,et al.  A Model for Chip Formation During Machining of Hardened Steel , 1996 .

[21]  Y. Kevin Chou,et al.  Tool wear mechanism in continuous cutting of hardened tool steels , 1997 .

[22]  K. Weinert,et al.  Relation between Process Energy and Tool Wear when Turning Hardfacing Alloys , 1994 .

[23]  Y. Yamane,et al.  The formation of a protective oxide layer in machining resulphurized free-cutting steels and cast irons , 1990 .