The Effect Of Grooved Surface Texture On Friction Noise

Friction noise with irregularly mutative frequency and sound pressure level is caused by the friction. In the industry, friction noise and vibration are considered to be greatly against the normal application of many friction systems and significantly reduce their service life and working efficiency, such as artificial joints, brake systems, wheel-rail system, machining systems, etc. Friction interface properties is one of the key factors for the friction noise. Therefore, the generation mechanism of friction noise is studied by investigating the influence of changing friction interface properties in this study. This will have a guiding meaning to find a good way to reduce and suppress friction noise.The influence of the change of friction interfereproperties on friction noise was investigated by machining grooved surface texture on braking disc materials (sample). Grooved surface texture (30μm in depth,150μm in width and500μm in pitch) was manufactured on the surface of vermicular graphite cast iron flat (brake disc material) by electromachining. Tribological tests of the grooved surface and smooth surface samples were carried out by using CETR-3multifunctional tribometer, different normal loads of3N、5N、 ION、20N、40N and reciprocating sliding frequencies of2Hz、0.3Hz、0.5Hz were used. Si3N4ceramic ball with10mm diameter was used as counterface ball and a ball-on-flat configuration was adopted. Both the vibration acceleration signal and frictional noise signal were collected during the tribological tests. Different signal processing methods including equivalent sound pressure level, coherence function and auto power spectrums were used to evaluated the vibration and noise signals. The effects of grooved surface texture on the vibration and noise properties of the friction system were studied. Moreover, the wear properties of the samples are evaluated by optical microscope and profilometer to reveal the influence of the grooved surface texture on friction interface properties. Finally, the influence of the grooved surface texture on friction noise was discussed from the viewpoint of tribology. Accordingly, the main conclusions can be drawn as following which are applicable only to the grooved surface texture adopted in this work:1. Time process curves of the friction noise of the groove-textured surface was different from those of the smooth surface. The friction noise of the groove-textured surface usually appeared in both strokes of reciprocating sliding. However, the friction noise of smooth surface normally appeared in just one stroke of reciprocating sliding.2. It is easier for the groove-textured surface to generate the friction noise compared to the smooth surface and with higher noise intensity. 3. Friction noise was prone to occur earlier for the groove-textured surface compared to the smooth surface, and more complex frequency components were found for the the groove-textured surface. This can be attributed to that the existence of grooved surface texture caused more components of the friction frequency during the reciprocating sliding. The increase of the friction frequency components would increase the probability of the coupling of the friction frequency and natural frequency of the system, and finally caused the vibration of multi-frequency of the system.4. The groove-textured surface adopted in this work exhibited higher coefficient of friction and wear resistance as compared to the smooth surface. The existence of grooved surface texture changed the fiction and wear behaviors as well as friction-induced vibration and noise properties of the frictional surfaces, but their corresponding relationship is not good.