Evaluation of wear of turning carbide inserts using neural networks

Recent trends, being towards mostly unmanned automated machining systems and consistent system operations, need reliable on-line monitoring processes. A proper on-line cutting tool condition monitoring system is essential for deciding when to change the tool. Many methods have been attempted in this connection.Recently, artificial neural networks have been tried for this purpose because of its inherent simplicity and reasonably quick data-processing capability. The present work uses the back propagation algorithm for training the neural network of 5-3-1 structure. The technique shows close matching of estimation of average flank wear and directly measured wear value. Thus the system developed demonstrates the possibility of successful tool wear monitoring on-line.     

NANO-MULTILAYERS WITH HIGH PERPENDICULAR ANISOTROPY FOR MAGNETIC RECORDING

(FePt/Ag)n nano-multilayers were deposited on MgO (100) single crystal with laser ablation and then subjected to annealing. FePt L1o grains with (001) texture and thus a large perpendicular magnetic anisotropy constant Ku of the order of 106 J/m3 were formed. A thick Ag layer is found to be favorable for decreasing the dispersion of the easy axis for magnetization. The measurement of time decay of magnetization gave rise to a small activation volume of the order of 10-25m3, showing the promising of being the recording medium for future high density perpendicular recording.     

Regular features of wear in heterogeneous structures of high-strength coatings

High-strength coatings on alloys of various morphology prepared by methods of surface impregnation are effective (wear resistant) in operation and economical in production. The requisite structure, wear resistance, and antifriction properties can be provided by a proper choice of the production technology of the coating and the quality parameters of the triboengineering layers, which determine the operating capacity, namely, the geometric (thickness of the coating and depth of the diffusion zone), structural (porosity, phase composition, substructural components), and physical and mechanical (macro- and microstresses, microhardness) parameters and the strength of cohesion with the substrate.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 21 – 25, June, 1996.     

The Oxidation Behavior of Y2O3-Dispersed β-NiAl

Y₂O₃-dispersed NiAl was produced by a powder-metallurgy process. By adding Y as an oxide dispersion (OD), problems with NiY_x formation and internal oxidation were avoided. Short-term isothermal and cyclic-oxidation performance at 1200°–1500° C was compared to cast NiAl alloys with and without Zr. Results indicate that the Y₂O₃ addition was beneficial to scale adhesion and significantly modified the α-Al₂O₃ scale microstructure, similar to a Zr alloy addition. However, at 1400 and 1500° C, neither the Y₂O₃ or Zr additions changed the scale-growth rate, eliminated the formation of voids at the metal-scale interface or prevented scale spallation. These similarities in performance suggest that similar mechanisms occur when the reactive element is added as either an OD or an alloy addition.     

High-speed milling of titanium alloys using binderless CBN tools

The performance of conventional tools is poor when used to machine titanium alloys. In this paper, a new tool material, which is binderless cubic boron nitride (BCBN), is used for high-speed milling of a widely used titanium alloy Ti–6Al–4V. The performance and the wear mechanism of the BCBN tool have been investigated when slot milling the titanium alloy in terms of cutting forces, tool life and wear mechanism. This type of tool manifests longer tool life at high cutting speeds. Observations based on the SEM and EDX suggest that adhesion of workpiece and attrition are the main wear mechanisms of the BCBN tool when used in high-speed milling of Ti–6Al–4V.     

The Fe-Ni (iron-nickel) system

The online version of the original article can be found at     

The assessment of thermal history in pressure vessel steel

A component of the present work involves attempts to simulate the microstructures of 1Cr-0.5Mo steel sample removed from service after extended exposure to elevated temperatures (10⁵ h at 535°C). The aim is to establish a basis for assessing the thermal history of service components and service weldments. Previous work has established that it is not possible to adequately simulate service microstructures using accelerated isothermal heat treatments alone. A selective mechanical testing program at elevated temperature has thus been investigated to superimpose the effect of stress on heat treatment. Qualitative comparison within each of these sets of micrographs suggests that the intraferritic precipitation in the creep samples is in each case refined and of a higher density compared to the sample subjected to isothermal heat treatments. It has been suggested that a comparison of the composition of the pearlitic M₃C in creep test samples with the empirical relationship may provide a means of assessing the average thermal history of the ex-service sample.