Search

Abstract: Manufacturers of machine tools face worldwide competition which is tightened by demands for total cost of ownership (TCO) contracts, requiring a guarantee of a certain availability of their products. This availability is naturally affected by wear of machine components. It depends on the use of the machine tool in daily operation and correlates with the occurring load spectrum. The real load spectrum, however, is widely unknown. When designing a machine tool, the future load application is estimated from the designer''s experience. The real loading from cutting operations and motion usually highly differs from these assumptions. Hence, multibody simulation in combination with controls and CNC simulation offers the possibility to investigate the realistic load spectra of several machine components when performing the simulated operation of a given CNC program. The load levels can be accounted for, and the overall wear time can be accumulated and allocated to wear regions on the components with respect to the stressing. Thus, the progress of component life consumption can be obtained by simulation, which is useful for the appropriate requirements towards the machine''s components at the point of the machine design. This paper will present a practical approach to the estimation of machine tool component life based on simulation. [Copyright &y& Elsevier]

Abstract: Oil-in-water (O/W) emulsions produced by static mixers in the laminar flow regime are characterized for their oil drop size spectra. The emulsions are used in the first process step for the production of microspheres for pharmaceutical applications by the emulsion extraction method. However, emulsion generation by static mixers in the laminar flow regime is rarely discussed in the scientific literature. Here we deduce a non-dimensional correlation for predicting the Sauter mean oil drop size as a function of the static mixer operation parameters and the liquid properties. First, the material properties of the organic and water phases are characterized. Second, the oil drop size spectra of the emulsions are measured by laser diffraction. Dimensional analysis is used to describe the relationship between the process parameters of the static mixer and the Sauter mean oil droplet size. Emulsion production experiments using SMX static mixers with two different diameters are carried out with the mixing of the two liquids taking place in the laminar flow regime. We provide results covering a wide range of all process parameters, which were identified influencing the droplet size of the emulsion. The correlation achieved is related to the non-dimensional drop-size based Ohnesorge number of the emulsification process and allows for the prediction of the mean oil droplet size with good accuracy, which is an essential information about the emulsion properties relevant for the pharmaceutical application. [Copyright &y& Elsevier]