Precursor monitoring approach for reliability assessment of cooling fans

Cooling fans are a critical part of the thermal management capability 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 ball bearings today. However, these fans are also prone to fail before 3 years. Prognostics and health management is a potential way to cost effectively and timely find low reliability fans. The first step for prognostics and health management is to identify precursor parameters. This article begins with the identification of precursor parameters. The health of cooling fans was estimated by monitoring three precursor parameters including acoustic noise emission, shaft rotational speed, and current consumption. Then the parameter value changes were compared to the failure criteria described in the IPC-9591 standard.