This paper presents a successful implementation of a real time inspection system of plastic bottle closures. The closures are inspected at a rate of 20 per second or one every 50ms. The available time to inspect each closure forces the algorithms used to be relatively simple. Even though the algorithms are simple, they have to be robust to ensure a good result. Two boundary tracking algorithms were designed and implemented, one based on edge strength information and one based on threshold information. Both use prior knowledge about the closure. The results are sufficiently accurate to replace a human operator with the machine inspection system. A description of the system including the timing and hardware used is given. The results achieved using each of the algorithms are presented. This is followed by a brief discussion of problems associated with achieving highly accurate results using a simple algorithms.