Testing of Newly Developed Functional Surfaces Under Pure Sliding Conditions

Abstract

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.

Validation of a coupled multibody and TEHL simulation by a piston/cylinder component test rig

“…Based on this design, the cylinder housing can only move in the axial direction. Whereby the force transmission rod (22), which is connected to the load 2), swash plate replica (3), control piston (4), control chamber/cylinder (5), cylinder housing (6), pressure sensor (7), temperature sensor (8), slipper pad (9), position sensor (10), hydraulic test cylinder (11), servo directional control valve (12), swash plate connection (hydraulic cylinder) (13), swash plate connection (control piston) (14), bearing block (15), eddy current sensor (16), sheet metal suspension (17), oil supply port (18), load cell (19), oil drain port (20).…”

“…In addition to the specification of the axial piston movement, it is possible to adjust the normal pressure in the contact by means of a conical housing. Within the scope of a follow-up study, 8 the influences of different surface textures were examined. An indirect method of friction force measurement without the need for a friction force sensor was demonstrated by Pan et al.…”

Off-line testing of multifunctional surfaces for metal forming applications

“…friction in pure sliding condition, with 50% friction forces reduction compared to turned or ground surfaces [18]. In this paper, the efficacy of MUFU surfaces is evaluated when applied on tools for metal forming applications, in which, differently from the case studied in [18], the tribological contact results in the plastic deformation of the softer body.…”

“…In this paper, the efficacy of MUFU surfaces is evaluated when applied on tools for metal forming applications, in which, differently from the case studied in [18], the tribological contact results in the plastic deformation of the softer body. In particular, deep drawing is the metal forming operation selected for the present investigation.…”