This paper presents results of the influence of cryogenic machining on the process stability. The stability diagrams are obtained experimentally using the coarse-grained entropy rate estimator for chatter detection from measured cutting forces. In comparison with conventional machining, enlarged stability windows are observed for the case of cryogenic machining. Based on the defined specific force models in turning operations, it is shown that a higher machining stability is achievable in cryogenic machining due to the reduction of specific cutting force components, in comparison with dry machining.
COBISS.SI-ID: 11827739
This study aims at investigating the effects of high-pressure jet assistance (HPJA) in rough turning of Inconel 718. A finite element (FE) model for orthogonal machining has been developed in order to reach additional data, compare trends to the experimental ones and understand the influence of the jet on the cutting process. Mechanical and thermal loads induced by the jet are considered. Consequences on the primary and secondary shear zones, chip formation and tool rake face have been studied on a whole pressure range (30-130 MPa) and compared to dry cutting. It is shown that the jet is able to decrease the cutting forces, chip radius and tool-chip contact length. Contact pressure and temperature fields on the cutting tool are also reduced as well as the sticking part of the contact zone. Authors confirmed that the effects of convection are able to change and even amplify the influence of the pure mechanical load induced by the jet.
COBISS.SI-ID: 11929883
This paper presents the major objectives involved in the development of a thin-layer palladium/ceramic composite membranes. These are (a) electroless plating of palladium on ceramic substrate, (b) characterization of palladium/ceramic composite formed, (c) evaluation of selectivity of the composite membranes for hydrogen separation. Commercially available ceramic was used as substrate for deposition of hydrogen selective layers. The substrate was coated with a thin palladium layer by electroless plating. The plating technique allowed to vary the thickness by depositing multiple metal layers. The details of the plating procedures and formulations of the plating solutions are presented. The palladium/ceramic composite membranes were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and measuring the thickness of the coated film by a weight-gain method. As a result, work proves that the hydrogen obtained in desorption step is of a high purity ()99.5% vol). Therefore,obtained results show that this kind of composite membranes have certain separation selectivity for hydrogen and can have good industrial applications.
COBISS.SI-ID: 11742747