Applicability of classic analytical calculation approaches for the design of plastic gears

Abstract

Plastic gears are produced cost-effectively in high volume but mainly for applications under low load. Current trends are leading to the design and application of plastic gears for more demanding operating conditions. This requires finding the optimum macrogeometry for the application, which is determined in practice using iterative design processes. Numerical and analytical approaches are available for the design of gears. Due to their speed, only the latter are suitable for an iterative design process. However, the approaches currently used in the calculation programs are designed with a focus on steel gears. Their applicability to gears made of plastics, which material properties differ drastically from those made of steel, is therefore only partially possible.The paper presents an investigation into the applicability of the classic analytical calculation approaches of Weber/Banaschek and Schmidt for contact analysis and the load-carrying capacity calculation of plastic gears. For this purpose, the results from analytical calculations are compared with those from numerical calculations. In addition, a comparison is made with typical standards (DIN3990, ISO6336) and guidelines (VDI2736).As a result, the paper provides an initial statement on the transferability of results from steel-focused analytical approaches to gears made of plastic. In addition, calculation results are identified in which particularly large differences occur between the various calculation approaches and which must be considered in the design phase.