Automated Scarf Repair for Composite Structures

acm7 Tracking Number 45

Composite scarfing is the current industry standard in repair of thermoset composites. This process requires sanding the damaged or defective composite and epoxying an undamaged fiber patch in the removed area. This highly manual and costly process can require days to complete and is subject to manufacturing errors. This paper investigates an approach to piece-wise automation of the scarf repair process. The automated setup integrates a mobile KUKA 6-axis robotic manipulator with a multi-tool end effector to perform the process. The end effector performs composite removal using a router tool, followed by epoxy deposition on the composite interface, and it uses a vacuum to pick and place a pre-made carbon fiber patch. The design and characterization of each end effector tool for creating the patch repair is described. Automated patch repair trials are conducted, starting from composite milling and concluding with patch placement. Manual patch repairs are performed to produce a comparison in structural quality. These repairs are each tested to failure under compression based on ASTM D7137. Stress analysis shows the automated patch repair is 5% weaker than manual repair, but with a reduction of around costs, and a time savings of more than 2.5 man hours when compared to manual repair.