The influence of environmental and manufacturing conditions on lifetime and reliability predictions for industrial timing belt drives

Timing belts are widely used for transmitting forces and torques. Despite the relatively simple design of timing belts, a lack of understanding of the respective system’s behavior can lead to flawed development, the results of which are unplanned failures and high warranty costs. The service lifetime of a timing-belt drive is influenced by a number of factors. In addition to pretensioning, timing-belt geometry and the torque to be transmitted, environmental conditions are among the most relevant factors. The operating temperature of the timing belt is a particularly key factor with regard to the lifetime.

Another factor that should not be neglected is the manufacturing process and thus the manufacturing quality of the timing-belt drive—especially of timing-belt pulleys. In order to gain a better understanding of the failure behavior of timing-belt drives and to underline the relevance of the lifetime problems with belt drives, this paper presents the results of an experimental investigation of the two factors “ambient temperature” and “timing-pulley feed rate”. A clear correlation between the ambient temperature and the lifetime of a timing belt could be demonstrated. In contrast, no significant influence on the failure behavior could be identified in the examined region in the case of the pulley feed rate. The test results can be used to mathematically describe a transfer function between the thermal stress and the lifetime (lifetime model). This lifetime model facilitates appropriate designs for timing-belt drives and lifetime prognoses for different temperatures.