Effect of grease composition on the friction characteristics of plastic materials

This is a report on experimental research conducted for the purpose of discovering a grease that is suitable for lubricating plastic materials. The plastics used in the experiment were nylon and polyacetal. The greases used had different thickeners and base oil viscosities. We investigated the effects of the thickener and the base oil viscosity on the lubrication characteristics. The results can be summarized as follows: 1) When the base oil viscosity is low, the friction coefficient is low, regardless of the type of thickener used. In addition, even if the base oil viscosity remains constant, the friction coefficient differs depending on the type of thickener. 2) Regardless of the type of grease used, the friction coefficient shows a dependence on the contact pressure; the higher the contact pressure, the lower the friction coefficient. The friction coefficient also depends on the speed; the friction coefficient increases as the speed increases. 3) Observations of the plastic sliding surface following the experiment revealed that for grease lubrication, even at relatively light load, solid friction occurs to some extent.