Friction Resistance of PA Plastic Used to Make the Sickle Insert of an Internal Gear Pump

Abstract

The use of plastics (PA) for the construction of pumps and hydraulic cylinders allows the production of light elements with unusual shapes. The article presents the results of tribological tests of PA for use as a material for the sickle insert of an internal gear pump. The research was carried out on a ball-on-disc test stand. The influence of load and rotational speed on the friction force in the PA-steel friction pair under mixed lubrication conditions was analysed. Based on the obtained tribological test results, it was found that the friction force of PA on steel in the presence of hydraulic oil (mixed lubrication) at a rotational speed below 1000 rpm does not exceed FT = 0.5 N. The obtained friction force values are strongly dependent on the load, but the optimal friction values were obtained at a rotational speed in the range of 600–700 rpm. The obtained results are comparable to those for other elastomeric materials used, e.g. for technical seals. It was suggested that tests be conducted to assess the durability (wear intensity) and structure (porosity) of the materials of the components to gain a thorough understanding of their suitability for use in hydraulic systems. The research results indicate avenues for further exploration aimed at designing optimal inserts that meet the requirements for a prototype pump, ensuring increased efficiency under higher forcing pressures.