Trailer based rail monitoring in overhead hoist transport systems

Abstract

In 300 mm semiconductor factories, overhead transport (OHT) systems used for safe and fast transportation of wafers. These systems consist of a rail network and OHT vehicles. The components of the rail system are subject to high stress through vehicle motion. Individual fault-related failures in the rail network can cause considerable damage and loss of production. Therefore, it is necessary to reduce the fault probability to a minimum. For this reason, extensive preventive maintenance should be used with such a rail system. In preparation to change to a condition-based maintenance strategy, we developed a measuring platform for rail condition monitoring. This article describes the design of this platform and presents a first example of 3-D measurement data acquisition for spatial alignments checks.