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The employment of surface texturing for improved tribological contacts has spread over the years. The possibilities of designing and manufacturing textured surfaces with predetermined geometries have multiplied as well as the need of performing experimental laboratory tests before applying the surfaces in an industrial context. In this paper a number of experimental tests were performed using a novel test rig, called Axial Sliding Test, simulating the contact of surfaces under pure sliding conditions. The aim of the experiments is to evaluate the frictional behavior of a new typology of textured surfaces, the so-called multifunctional surfaces characterized by a plateau area able to bear loads and a deterministic pattern of lubricant pockets. Six surface typologies, namely three multifunctional and three machined using classical processes were chosen to slide against a mirror-polished counterpart. A number of experiments were carried out at different normal pressures employing for all specimens the same reciprocating movement and the same lubrication. The measured friction forces were plotted against the incremental normal pressure and the friction coefficients were calculated. The results comparison showed clearly how employing multifunctional surfaces can reduce friction forces up to 50% at high normal loads compared to regularly ground or turned surfaces. Friction coefficients approximately equal to 0.12 were found for classically machined surfaces, whereas the values were 0.06 for multifunctional ones. All the specimens were characterized before and after testing. Wear occurrence was not detected on the tested surfaces except on the mirror-polished one which underwent all the experiments.

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This paper addresses the establishment of traceability of optical 3D scanner measurements on green sand mould in the production of quality castings. Optical measurements are subject to the influence of the workpiece material optical properties, which can be very different from those of conventional calibration artefacts, e.g. check boards, ball plates, etc. This means that an optical 3D scanner calibrated using a check board or a ball plate may give biased and unreliable results when used for dimensional measurements on a crystalline material such as sand. In order to use a tactile coordinate measuring machine as reference for optical measurements on a green sand mould, which cannot be probed directly, a hard furan sand cone plate was developed and substituted as reference workpiece for tactile as well as optical measurements. Systematic errors and measurement uncertainties were assessed for the optical measurements, and a maximum expanded uncertainty of 26 µm was estimated, which is acceptable for optical measurements on sand surfaces having single grains with an average diameter of 232 µm.