Izr. prof. dr. Jože Tavčar, univ. dipl. inž., dr. Borut Černe, mag. inž., prof. dr. Jože Duhovnik, univ. dipl. inž., dr. Damijan Zorko, mag. inž., vsi Univerza v Ljubljani, Fakulteta za strojništvo

Abstract:
Reliable polymer gear design remains to date an open challenge due to a lack of data regarding the specific properties of polymer materials and due to complex relationships between the gears’ geometric parameters and the applied running loads. Several standards (BS 6168: 1987, JIS B 1759: 2013) and guidelines (VDI 2736) are available for designing polymer gears, however, all of them hold certain limitations. In most cases, engineers do not have the full picture regarding the interactions between all design parameters, which often leads to multiple design iterations and prototypes before an ideal design solution can be obtained. In this contribution, a systematic analysis of the main design criteria for cylindrical polymer gears is presented, i.e. the root and flank strength, temperature, wear, deformation, gear quality, installation quality, volume and production costs. The sensitivity and interdependence between different parameters are presented in a number of illustrative diagrams. The article concludes with an overview of the most typical gear failure modes exhibited by different material pairs at various load levels and a systematic and concise guideline how to improve key design criteria in order to achieve a viable solution. In the subsequent journal edition, a further presentation of a custom developed algorithm for a multicriteria optimization of polymer gears will be presented along with a case study implementation.

Keywords:
polymer gears, design, failure modes, optimization