Precision surface characterization for finish cylindrical milling with dynamic tool displacements model

In this work a new approach to surface roughness parameters estimation during finish cylindrical end milling is presented. The proposed model includes the influence of cutting parameters, the tool’s static run out and dynamic phenomena related to instantaneous tool deflections. The modeling procedure consists of two parts. In the first stage, tool working part instantaneous displacements are estimated using an analytical model which considers tool dynamic deflections and static errors of the machine – tool-holder – tool system. The obtained height of the tool’s displacement envelope is then applied in the second stage to the calculation of surface roughness parameters. These calculations assume that in the cylindrical milling process, two different mechanisms of surface profile formation exist. Which mechanism is present is dependent on the feed per tooth and the maximum height of the tool’s displacement envelope. The developed model is validated during cylindrical milling of hardened hot-work tool steel 55NiCrMoV6 using a stylus profiler and scanning laser vibrometer over a range of cutting parameters. The surface roughness values predicted by the developed model are in good agreement with measured values. It is found that the employment of a model which includes only the effect of static displacements gives an inferior estimation of surface roughness compared to the model incorporating dynamic tool deflection

Investigation of Adhesion and Tribological Behavior of Borided AISI 310 Stainless Steel

In the present study, the effects of the boriding process on adhesion and tribological properties of AISI 310 steel were investigated. Boriding was performed in a solid medium consisting of Ekabor-II powders at 1123 and 1323K for 2 and 6 h. The boride layer was characterized by optical microscopy, the X-ray diffraction technique and the micro-Vickers hardness tester. The X-ray diffraction analysis of the boride layers on the surface of the steels revealed the existence of FexBy, CrxBy and NixBy compounds. Depending on the chemical composition of substrates, the boride layer thickness on the surface of the AISI 310 steel was found to be 56.74 μm. The hardness of the boride compounds formed on the surface of the AISI 310 steel ranged from 1658 to 2284 HV0,1, whereas the Vickers hardness value of the untreated steel AISI 310 was 276 HV0,1. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10N and with a sliding speed of 0.3 m/s, at a sliding distance of 1000m. The wear surfaces of the steel were analyzed using an SEM microscopy and X-ray energy dispersive spectroscopy EDS. It was observed that the wear rate of unborided and borided AISI 310 steel ranged from 4.57 to 71.42 mm3/Nm

Diffusivity, solubility and permeability of water vapor in flexible PVC/silica composite membranes

WOS: A1996UR18100011Flexible PVC/silica composite membranes having a porous structure have been produced using plastisol-plastigel technology. Equilibrium and rate studies related to water vapor adsorption on membranes have been studied using a Cahn 2000, gravimetric adsorption system. For the solubility and diffusivity of water vapor in membranes 4.23-7.74 cm(3)/(cm(3) cmHg) and 2.0-3.5 x 10(-13) m(2)/s values have been determined respectively. The measured permeability of water vapor through membranes 1.6-7.3 x 10(-6) ((cm(2)/s)/(cm(2) cmHg))cm, were much higher than predicted permeabilities 0.85-2.73 x 10(-8) ((cm(2)/s)/(cm(2) cmHg))cm. from solubility diffusion data, indicated the membranes had a porous structure. The membranes are suggested as a leather substitute since the permeability through membranes is comparable to that of leather and is at least 100 times higher than that of plasticized PVC film obtained by conventional processing techniques