Non-Contact Capacitance-Probe System for Part Inspection

Inspection of parts for dimensional compliance is a common task in prototyping, manufacturing, and quality assurance. In prototyping and quality control courses, students gain an appreciation for the importance, intricacies, and often time-consuming nature of parts inspection that can negatively impact productivity. Here we report a student project for designing, fabricating, and testing a non-contact capacitive probe station that can check the pitch and surface figures of threaded parts featuring multiple thread sizes, with a cycle time of 5 seconds. The performance, cost, and capabilities can be compared to machine vision inspection of parts using a CCD camera and image analysis software. This desktop modular system can be retrofit to CNC machines for in-line, real-time inspection, and includes network data communication capability. This effort was an 8-month Senior Design capstone project for Engineering Technology students.