Effect Of Thickener Types On Elastohydrodynamic Friction Characteristics Of Grease

In this paper,the effect of thickener type and base oil viscosity on the friction performance of grease was studied under the condition of sufficient grease supply.The micro traction testing machine(MTM)can simulate the working state of bearings and measure the Elastohydrodynamic friction characteristics of two groups of grease with different thickener types and two groups of base oil viscosity under different working conditions.According to the experimental requirements,the base oils are polyol mineral oil and synthetic oil,and the thickeners are lithium based thickener and urea based thickener.In addition,three different viscosities of polyurea grease were prepared with mineral base oil with viscosity of 48mm/s~2,68mm/s~2and 220mm/s~2,and polyurea as thickener;four kinds of Mineral Lithium Grease with different viscosity were prepared with mineral oil base oil with viscosity of48mm/s~2,68mm/s~2,110mm/s~2and 220mm/s~2,respectively,and lithium base oil as thickener.The storage modulus and loss modulus measured by microscope and rheometer show that the filament winding degree of grease with different viscosity increases first and then decreases with the increase of grease viscosity.The experimental results also show that the friction coefficient of grease first increases and then decreases with the increase of base oil viscosity.When the viscosity of grease is 110 mm/s~2,the filament winding degree is the highest,the structure is the most stable,and the influence of environment is the least,but the friction coefficient is relatively large.According to the experimental requirements,four kinds of grease with viscosity of 68mm/s~2,polyol mineral oil and synthetic oil as base oil,and lithium base thickener and urea based thickener with 280 consistency were prepared.The storage modulus and loss modulus measured by microscope and rheometer show that the filament winding degree of polyurea grease is significantly higher than that of lithium grease,polyurea grease has stronger anti-interference ability than lithium grease,and polyurea grease is easier to adsorb on metal surface to form lubricating oil film,so the friction coefficient is smaller.Therefore,the friction characteristics of polyurea thickener are better than that of lithium grease.