Comparison of rolling contact fatigue life using a mineral oil, a synthetic polyester and a compound of both of them

This work evaluates the rolling contact fatigue life of AISI steel bearing balls with a lubricant made up of a neutral mineral oil and synthetic polyester. This second oil can be considered as environmental friendly, non-toxic and biodegradable. The obtained results were compared with the corresponding pure oils identified by means of infrared spectrums. The failure mechanism evaluation was made through rolling contact fatigue test in a modified Stanhope Seta-Shell according to IP 300 standard at 1,475 rpm with a load of 600 kg. A specific software, Weibull++ by Reliasoft, was used to procure life data analysis and to obtain lifetime distribution diagrams. Reliability plots, like SN curves, mean life, failure rate and L10 and L50 values were estimated for the compound lubricant as for the pure oils. The results prove that the lubricant composed of SN-350 and a 10% of TMP-05 has a longer fatigue life than the original pure-base oils SN-350 and TMP-05. Adsorption mechanism, evaluated by means of contact angle measurement would explain the observed behaviour during the test.