An analytical model for prediction of tool temperature fields in metal cutting processes is developed. The model can be applied to any continuous or interrupted three-dimensional cutting process. To accurately represent the heating and cooling cycles encountered during interrupted cutting, the analysis predicts time dependent heat fluxes into the cutting tool. A time history of this heat flux is obtained by performing an energy balance on the chip formation zone. The variation with time of the tool temperature fields is determined from a heat transfer analysis with prescribed heat generation rate. The analysis requires the cutting forces as inputs. The model tool-chip interface temperatures agree well with the experimental tests reported in the literature, for all cutting conditions and work materials investigated. The results indicate that the tool-chip interface temperature increases with cutting speed during both continuous and interrupted cutting.

A mechanistic dynamic model is used to simulate a face milling process during constant and variable speed machining. The model can be used to predict the optimum speed trajectory that can provide a low level of vibration and consequently a large productivity rate and a small surface error. The model is used to investigate the vibration of face milling processes that have one, or multiple coupled modes of vibration acting throughout the cut. For cutting processes having one dominant mode of vibration, the model predicts that variable speed machining is especially effective over constant speed machining when the tool-work system changes its dominant mode of vibration throughout the cut, or when the tool-work system has several modes of vibration coming from component parts that are cut in the same time. For cutting processes having multiple dominant modes of vibration, the model predicts that variable speed machining is especially effective over constant speed machining when the tool-work modes of vibration are unequal and moderately coupled to each other. Also, the model suggests that for tool-work systems having complex geometries with dynamics hard to predict, variable speed machining is safer to use than constant speed machining when trying to achieve high productivity rates. This is due to the fact that variable speed machining is robust with respect to the dynamics of the tool-work system. Finally, the model predictions are in good agreement with the experiment.

The natural gas consumption of the operators connected to the gas transport system depends on the gas needs. As gas needs vary in time, the whole process of gas transportation is, therefore, nonstationary. The paper presents nonstationary simulations for a gas transportation network and highlights the parameters values (flows, pressures) that are necessary to assure the safety of the system.

A comparative study is presented on decontamination of the solutions containing 226Ra(II), by applying coprecipitation of Ba(Ra)SO 4 followed by flotation and selective adsorption on active carbon. The comparative study revealed the performances of separation by coprecipitation-flotation and the possibility of applying the selective adsorption on active carbon. Both methods ensure the decreasing of 226Ra(II) concentration under the allowed limits, recommended by International Standards.

Part 2 of this paper focuses on the explanation, both on theoretical grounds and through model simulations, of why the technique of variable spindle speed machining is an effective tool for increasing the quality and productivity of machining operations. In particular, Part 2 explains why, by disturbing the regenerative and forced vibration excitation frequencies which generate large amplitudes of vibration during constant speed machining, variable speed machining has the potential to reduce the vibration of the tool-work system and be robust with respect to the cutting process dynamics. The explanation is based on the work done by the cutting forces, the chip load variation, tool-work displacements, cutting forces, and workpiece surface error generated by both constant and variable speed machining. By investigating the effects of regeneration and forced vibration during variable speed machining on the vibration of tool-work systems having different cutter diameter-to-workpiece width ratios, it has been shown that variable speed machining is also robust with respect to the geometry of the tool-work system. This work concludes that variable speed machining is safer to use than constant speed machining when the effects of the tool-work dynamics and geometry on the vibration of the cutting process are hard to determine.