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New alumina coatings with outstanding performance in milling and turning operations
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LITERATURE
REVIEW
September issue) PROPERTIES AND APPLICATIONS OF CERAMIC CUTTING TOOL MATERIALS
APPLIED ANALYTICAL TOOLS FOR THE CHARACTERIZATION OF CERMETS
H.K. Tonshoff et al, (University of Hanover, Germany). The use of A1203 and SiN2 tool material in metal cutting was discussed in regard to turning and face milling. Wear mechanisms, tool/workpiece interactions, temperature effects and the effects of load functions were considered. Aims for m a t e r i a l s i m p r o v e m e n t s and m a c h i n i n g and machining design changes were given.
P. Wilhartitz et al, (Metalwerk Plansee GmbH, Reutte, Austria). Methods for the analysis and characterization of cermets were reviewed with respect to the information obtained and the applicability to routine analysis. Wet chemical methods for dissolution of binder phases were reported to have been optimized and the surface of carbide p a r t i c l e s c h a r a c t e r i z e d by s c a n n i n g electron microscopy with energy dispersive analysis. The compositions of binders was determined by atomic, absorbtion and enmission spectroscopes. Threedimensional secondary ion mass spectroscopy (SIMS) was applied to the study of concentration profiles in carbide grains and matrix to a lateral resolution of 0.5 [am and a depth resolution of 10 I~m. Transmission electron microscopy (TEM) was also used because of its superior lateral resolution but it was pointed out that TEM is limited due because of the small volume of material analysed.
SYSTEM DESIGN ANALYSIS AND PRODUCTION OF CUTTING TOOLS S.F. Wayne et al, (GTE Laboratories Inc, Waltham, Massachusetts, USA). Productivity in machining operations, using a d v a n c e d c u t t i n g tools was discussed in terms of the balance between mechanical properties of tool materials and tool geometry, cutting forces and control of chip formation. A system which integrates computer aided design and manufacturing (CAD/CAM) and machinability data to allow for design and rapid phototyping of new m e t a l c u t t i n g g e o m e t r i e s w a s d e s c r i b e d . The c u t t i n g o p e r a t i o n is simulated and used as the analytical basis of the system. The computer modelling uses non-linear finite element methods which account for the m e c h a n i s m s of chip formation and the interactions with tool materials. The implications of the system were discussed. FACTORS LEADING TO IMPROVED THERMAL CRACKING RESISTANCE IN CARBIDE MILLING INSERTS J.E. Peters and B.D. Hoefler, (American National Carbide Co, Tomball, Texas, USA). Thermal cracking as a cause of tool i n s e r t f a i l u r e w a s d i s c u s s e d . An investigation of the effects of C content was carried out and determinations were made of residual stress in the binder phase and of binder phase chemistry. It was suggested that a connection exists between C level, residual stress and the tendency to suffer thermal cracking.
50 MPR October 1992
ABILITY OF MECHANICAL TESTS TO DISCRIMINATE BETWEEN TUNGSTEN CARBIDE HARDMETALS W. Coles and B. Roebuck, (National Physical Laboratory, Teddington, UI0 . Mechanical test procedures were reviewed with respect to their ability to discriminate between materials. Tests on two WC-6 wt%Co hardmetals were carried out. Specimens were prepared from the same WC powders. One had regions of Co several microns in diameter and the other had a more uniform distribution of WC and Co. Of the six tests used only notched bend and abrasive wear tests discriminated between the two alloys. NEW DEVELOPMENTS IN PHYSICAL VAPOUR DEPOSITED HARD COATINGS H.W. Holleck, (Kernforschungszentrum Karlsruhe, Germany). The development of coatings, based on i m p r o v e d u n d e r s t a n d i n g of coatings, structures, properties and behaviour of
coated materials, was reviewed. Mixed p h ase layers, c o m p o s i t i o n a l l y graded coatings, multi-layers and nano-crystalline multi-phase layers were considered with respect to structures and properties. New coating materials were compared with coatings applied by conventional chemical and physical vapour deposition processes. INDUSTRIAL APPLICATION OF BORON CARBIDE COATING TECHNOLOGY B. Thomassery and P. Nisio, (Coating Development, St. Etienne, France). It was pointed out that BC is the third hardest material, after diamond and cubic BN, the Vicker's hardness being about 6000. The high hardness leads to a range of application in cutting tool technology. The preparation of BC coatings using low pressure chemical vapour deposition was outlined. Some industrial results were presented and a comparison with other coatings was made. NEW ALUMINA COATINGS WITH OUTSTANDING PERFORMANCE IN MILLING AND TURNING OPERATIONS E. Kubel, (Walter Hartmetall GmbH, Musingen, Germany). I m p r o v e m e n t s in c h e m i c a l v a p o u r deposition processes and the use of special substrate materials were reported to lead to improvements in the performance of A1203 coated cutting tool materials. Applications in milling and turning were shown and were reported to lead to markedly increased machining efficiency. ROLE OF THE DIAMOND-SUBSTRATE INTERFACE IN CHEMICAL VAPOUR DEPOSITION (CVD) OF DIAMOND G. Demazeau et al, (University of Bordeaux, France). Methods of applying CVD diamond films, high pressure/high temperature and low pressure/high temperature, were discussed. The latter leads to thin films. Nucleation had crystal growth were analysed in terms of local chemical bond and structure of the interface between diamond coating and substrate.
LITERATURE
REVIEW
September issue) PROPERTIES AND APPLICATIONS OF CERAMIC CUTTING TOOL MATERIALS
APPLIED ANALYTICAL TOOLS FOR THE CHARACTERIZATION OF CERMETS
H.K. Tonshoff et al, (University of Hanover, Germany). The use of A1203 and SiN2 tool material in metal cutting was discussed in regard to turning and face milling. Wear mechanisms, tool/workpiece interactions, temperature effects and the effects of load functions were considered. Aims for m a t e r i a l s i m p r o v e m e n t s and m a c h i n i n g and machining design changes were given.
P. Wilhartitz et al, (Metalwerk Plansee GmbH, Reutte, Austria). Methods for the analysis and characterization of cermets were reviewed with respect to the information obtained and the applicability to routine analysis. Wet chemical methods for dissolution of binder phases were reported to have been optimized and the surface of carbide p a r t i c l e s c h a r a c t e r i z e d by s c a n n i n g electron microscopy with energy dispersive analysis. The compositions of binders was determined by atomic, absorbtion and enmission spectroscopes. Threedimensional secondary ion mass spectroscopy (SIMS) was applied to the study of concentration profiles in carbide grains and matrix to a lateral resolution of 0.5 [am and a depth resolution of 10 I~m. Transmission electron microscopy (TEM) was also used because of its superior lateral resolution but it was pointed out that TEM is limited due because of the small volume of material analysed.
SYSTEM DESIGN ANALYSIS AND PRODUCTION OF CUTTING TOOLS S.F. Wayne et al, (GTE Laboratories Inc, Waltham, Massachusetts, USA). Productivity in machining operations, using a d v a n c e d c u t t i n g tools was discussed in terms of the balance between mechanical properties of tool materials and tool geometry, cutting forces and control of chip formation. A system which integrates computer aided design and manufacturing (CAD/CAM) and machinability data to allow for design and rapid phototyping of new m e t a l c u t t i n g g e o m e t r i e s w a s d e s c r i b e d . The c u t t i n g o p e r a t i o n is simulated and used as the analytical basis of the system. The computer modelling uses non-linear finite element methods which account for the m e c h a n i s m s of chip formation and the interactions with tool materials. The implications of the system were discussed. FACTORS LEADING TO IMPROVED THERMAL CRACKING RESISTANCE IN CARBIDE MILLING INSERTS J.E. Peters and B.D. Hoefler, (American National Carbide Co, Tomball, Texas, USA). Thermal cracking as a cause of tool i n s e r t f a i l u r e w a s d i s c u s s e d . An investigation of the effects of C content was carried out and determinations were made of residual stress in the binder phase and of binder phase chemistry. It was suggested that a connection exists between C level, residual stress and the tendency to suffer thermal cracking.
50 MPR October 1992
ABILITY OF MECHANICAL TESTS TO DISCRIMINATE BETWEEN TUNGSTEN CARBIDE HARDMETALS W. Coles and B. Roebuck, (National Physical Laboratory, Teddington, UI0 . Mechanical test procedures were reviewed with respect to their ability to discriminate between materials. Tests on two WC-6 wt%Co hardmetals were carried out. Specimens were prepared from the same WC powders. One had regions of Co several microns in diameter and the other had a more uniform distribution of WC and Co. Of the six tests used only notched bend and abrasive wear tests discriminated between the two alloys. NEW DEVELOPMENTS IN PHYSICAL VAPOUR DEPOSITED HARD COATINGS H.W. Holleck, (Kernforschungszentrum Karlsruhe, Germany). The development of coatings, based on i m p r o v e d u n d e r s t a n d i n g of coatings, structures, properties and behaviour of
coated materials, was reviewed. Mixed p h ase layers, c o m p o s i t i o n a l l y graded coatings, multi-layers and nano-crystalline multi-phase layers were considered with respect to structures and properties. New coating materials were compared with coatings applied by conventional chemical and physical vapour deposition processes. INDUSTRIAL APPLICATION OF BORON CARBIDE COATING TECHNOLOGY B. Thomassery and P. Nisio, (Coating Development, St. Etienne, France). It was pointed out that BC is the third hardest material, after diamond and cubic BN, the Vicker's hardness being about 6000. The high hardness leads to a range of application in cutting tool technology. The preparation of BC coatings using low pressure chemical vapour deposition was outlined. Some industrial results were presented and a comparison with other coatings was made. NEW ALUMINA COATINGS WITH OUTSTANDING PERFORMANCE IN MILLING AND TURNING OPERATIONS E. Kubel, (Walter Hartmetall GmbH, Musingen, Germany). I m p r o v e m e n t s in c h e m i c a l v a p o u r deposition processes and the use of special substrate materials were reported to lead to improvements in the performance of A1203 coated cutting tool materials. Applications in milling and turning were shown and were reported to lead to markedly increased machining efficiency. ROLE OF THE DIAMOND-SUBSTRATE INTERFACE IN CHEMICAL VAPOUR DEPOSITION (CVD) OF DIAMOND G. Demazeau et al, (University of Bordeaux, France). Methods of applying CVD diamond films, high pressure/high temperature and low pressure/high temperature, were discussed. The latter leads to thin films. Nucleation had crystal growth were analysed in terms of local chemical bond and structure of the interface between diamond coating and substrate.