In the present paper, the variation of surface roughness of machined parts during symmetrical face milling is investigated. During this experimental work, the effect of using a milling insert with a round geometry under various feed rate values on the topography of milled parts is examined. For that purpose, both 2D and 3D surface roughness measurements were performed in three planes parallel to the feed direction, with one of the planes being on the symmetrical plane and the other two being at the same distance from it but in opposite sides. The analysis of the experimental results indicated that although surface roughness increases gradually with increase of feed rate, a considerable increase of surface roughness occurs for feed rate values over 0.4 mm/tooth. Moreover, the overall higher surface roughness values were found to be on the symmetrical plane, which was also more affected by the increase of feed rate than the other two planes.

The remarkable tribological attributes of the gecko feet have grown much interest in the field of biomimetic tribology over the past two decades. It has been shown that the complexity of friction and adhesion phenomena made it difficult to transfer these exceptional properties into fully functional smart, dry, micro patterned adhesives. The latter, combined with the relative lack of literature on computational oriented studies on these phenomena, is the motive of the current work. Here, a 2D time-dependent finite element model of friction and adhesion attributed contact of polydimethysiloxane (PDMS) micro flaps with a smooth SiO2 spherical surface is presented. The model is tested through simulations concerning changes in the disc curvature, the flap density, as well as different disc mounting heights, representing the effect of preload. Furthermore, the effect of tribological parameters of adhesion and friction coefficient is discussed. Finally, the effect of the use of two hyperelastic material models was examined.

Abrasive Waterjet (AWJ) machining is considered an excellent alternative to conventional machining processes due to its superb machining characteristics. More specifically, Abrasive Waterjet drilling is nowadays a promising non-conventional process for obtaining high quality holes. In the present study, drilling experiments based on Taguchi L9 orthogonal design method were conducted via AWJ on carbon fiber reinforced polymer (CFRP) plate at various waterjet parameters, namely, different pressure, abrasive mass flow rate and standoff distance values. The purpose of the experiments was to investigate the impact of these process parameters on the quality of holes. The hole quality was determined by measuring the hole diameter error as well as the hole taper. The optical evaluation was implemented with the use of optical microscope and special measuring software. The ANOVA analysis of the results showed a significant influence of standoff distance regarding the hole diameter error and a combined influence of waterjet pressure and standoff distance regarding the hole taper. Furthermore, the optimal process parameter values for the optimization of the hole diameter error and hole taper were determined. The hole quality in terms of defects appearance was also quantitatively inspected, through optical imaging.