Study on the interaction mechanism between degradation behavior of grease and evolution of friction interface properties under static storage conditions

Long-term static storage of the ball screws result in interactive degradation of the grease and the friction interface, affecting the safety of equipment operation. In this study, the physical structure of the grease under static storage was found to be a sensitive factor for degradation. Subsequently the interaction mechanism between degradation of grease and the evolution of interface property was revealed. The aggregation and adsorption behaviors of thickener-base oil, thickener-metal interface, and base oil-metal interface were investigated by the molecular dynamic simulation. Further, interface characteristics and grease degradation respectively affect the value and duration of the growth phase of friction. This study can provide guidance for the phenomenon of increased starting torque of equipment relying on ballscrew after long-term standby.