Identification of Failure Precursor Parameters for Cooling Fans

Cooling fans have been a critical part of the thermal management of commercial and military electronic equipment. Although accelerated testing by increasing operating temperatures has been commonly adopted in order to estimate the reliability of cooling fans in a short time frame, the testing time is usually more than 6 months due to the high reliability of current ball bearings. Prognostics and health management is a potential way to solve this problem. The first step in PHM is to identify precursor parameters. This article begins with the identification of precursor parameters from published studies and failure modes, mechanisms, and effects analysis (FMMEA). The health of cooling fans was estimated by monitoring three precursor parameters including acoustic noise, shaft rotational speed, and current consumption. Then the parameter value changes were compared to the failure criteria described in the IPC-9591 standard.