Technological study of oil-filled polyamide parts

Abstract

The work develops a technology that provides an increase in the operational properties of the surface layer of finished polyamide parts in order to increase wear resistance without affecting their load-bearing capacity. To study the impregnation of a polyamide-6 sample with a mixture of motor oil and hexane, full-scale experimental research was carried out following the algorithm developed using a laboratory unit. In the work, the program code for the control board was used that operates in conjunction with the PowerGraph software for processing the acquired data. During the study, a method for drying samples with the dimensions of 4x50x50 mm in a high-frequency electric field (up to 2500 Hz) was selected in order to heat and remove moisture from the polymer evenly within a short period. Darcy's law describing the process of impregnating polyamide with oil was used. In order to increase the efficiency of impregnation and reduce the viscosity of the filler, its optimal composition was determined: a mixture of M-8B engine oil and hexane at a ratio from 8:2 to 4:6, respectively. A setup based on the UZP-2500 device was developed and automated by introducing a control board and sensors to measure the strength of the anode current and temperature of a polyamide sample. In addition, a regulating device with the power of a high-frequency generator operating in the current range of 0.25–0.35 A was built into the unit. Under the processing modes (the temperature of the polyamide sample is 75°C; the hexane content in the mixture is 40%), a method for controlling the drying temperature was established by switching off the high-frequency generator for 700 ms. The research results allow a new technological process of oil filling in polyamide parts operated in friction units to a given depth at known values of the impregnation rate to be developed. These results can help to increase the wear resistance and, consequently, the service life of the surface layer of finished polyamide parts used in railway wagon trucks exposed to friction and wear.