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ABSTRACT
Technical polymers are widespread in the machinery owing to their beneficial properties against metals as operation without lubrication, low friction and wear, light weight, corrosion resistance, low manufacturing costs etc. There are many sorts of technical polymers available of which sliding elements can be produced.[1] To choose proper polymers for a given tribological application is not a simple task owing to many different parameters influencing the performance of a polymer sliding element. We launched a broad research project to clarify the friction and wear phenomena of plastic gears. With this presentation we introduce the newly developed measuring system for studying the friction process between the meshing gears.
1. INTRODUCTION
In many cases investigations on tribometers in laboratory are used to compare the tribological properties of different polymer/metal pairs. In our institutes also many investigations on the tribological properties of technical polymer/steel pairs were performed on different tribometers. The main results were published earlier [2, 3]. Regarding the different ranking of polymer/steel pairs from the point of view of friction and wear obtained by many different tribometers and test-systems, it would be difficult to choose the best polymer/steel pair to make a polymer gear. Based on the survey of the semi-finished engineering polymer distributors and producers we selected the top five engineering polymers used for gears on the European market to investigate their friction and wear properties using test gears.
2. MATERIALS
The properties of the investigated polymers are presented in the Table 1.
The gear mating with polymer gears was made of structural steel S355 with a surface finish (CLA) R^sub a^ 2,5 µm.
3. FRICTION EXPERIMENTS WITH REAL GEARS
In the literature we can find different theoretical approach of the gearmesh [5, 6, 7, and 8] but no real information of the polymer/steel friction pairs. We started to approach the phenomena with a real gear tests.
During the experiments a large variety of tangential speed between 0.01 - 0.15 m/s and torque between 0.1 - 0.4 Nm were applied resulting many graphs to evaluate. During the experiments on a polymer/steel spur gear pair loaded with a constant applied torque the radial component (F^sub r^) and the tangential component (F^sub t^) of the tooth force were measured (Fig.2). The variation of the...