Improved Briles Rivet Forming Using High-Speed Force Feedback and Improved Die Geometry

Electroimpact and Kawasaki Heavy Industries (KHI) have produced a new riveting process for the forming of Briles type rivets in Boeing 777 and 777X fuselage assemblies. The Briles rivet is typically used for fuselage assembly and is unique in that it has a self-sealing head. Unlike conventional headed rivets such as the NAS1079, this fastener does not require aircraft sealant under the head to be fluid tight. This unique fastener makes for a difficult fastening process due to the fact that interference must be maintained between the hole and fastener shank, as well as along the sides of the fastener head. Common issues with the formed fasteners include gapping under the fastener head and along the shank of the fastener.

Electroimpact has employed a host of different technologies to combat these issues with Briles fastening. First, Electroimpact’s patented “Air Gap” system allows the machine to confirm that the head of the rivet is fully seated in the countersink prior to forming. If the fastener head is not seated prior to forming then there is no chance of reliable formed fastener quality. Second, Fanuc pressure control is used to control the forming process. Pressure control allows the machine to form the fastener, following a “force path” using a load cell as the feedback device. Third, specialized upper die geometry was developed to improve fastener head seating during fastening. By changing the pressure profile on the head, these dies help to eliminate gapping under the fastener head.