Design of precision measurement system for metallic hole
For most of the high speed hole diameter measuring process, a contact measuring method is undesirable due to its slow and destructive touching process. Thus, an optical method is usually chosen for non contact measurement. Unfortunately, for most holes in precise manufacturing, especially those with a high aspect ratio, the optical method cannot be used. In our study, we developed a simple and low cost precision capacitive hole measuring system. By using a simple alignment mechanism, we prove that a high resolution hole diameter can be achieved. Comparing a traditional measuring method like coordinate measuring machine with our system, over 99% correlation is easily obtained. The paper also presents a multilayer hole measuring probe and sensor probe for non through hole measurement.