Measurement of Fastener Head Protrusion in Automated Systems with a Capacitive Sensor

A capacitance sensor has been developed for measuring the protrusion of fastener heads. The capacitance sensor is easily integrated into an automated rivet installation system. The sensor is capable of measuring the protrusion of a fastener head relative to the skin surface, even in the presence of corrosion protective films used on the aircraft skin surface during manufacture.

This paper presents a brief review of the capacitance measurement method. The mechanical design and operation of the sensor are presented as well as information regarding the integration of the sensor within an automated riveting system.

Another novel capacitance-based inspection system has been developed for characterization of critical fastener dimensions. Design, capabilities, and inspection data obtained with the fastener measurement system are presented.

A Capacitance Measurement System for the inspection of fastener hole quality has been used by numerous aerospace manufacturers and end users for over a decade. The two new sensors discussed in this paper utilize the same electronics and operating principles of the hole inspection system to solve new measurement requirements as the needs for Statistical Process Control data evolve.