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The effectiveness of serial link articulated robots in aerospace drilling and fastening is largely limited by positional accuracy. Unguided production robotic systems are practically limited to +/-0.5mm, whereas the majority of aerospace applications call for tolerances in the +/-0.25mm range. The precision with which holes are placed on an aircraft structure is affected by two main criteria; the volumetric accuracy of the positioner, and how the system is affected when an external load is applied. Production use and testing of off-the-shelf robots has highlighted the major contributor to reduced stiffness and accuracy as being error ahead of the joint position feedback such as backlash and belt stretch. These factors affect the omni-directional repeatability, thus limiting accuracy, and also contribute to deflection of the tool point when process forces are applied.

Automated Fiber Placement (AFP) equipment has been developed capable of laying fiber in excess of 2000 inches per minute on full-size, complex parts. Two such high-speed machines will be installed for production of a nose section for a large twin-aisle commercial aircraft fuselage at Spirit AeroSystems in Wichita, Kansas along with a rotator for the fuselage mandrel. The problem of cutting and adding on the fly at these speeds requires thorough re-evaluation of all aspects of the technology, including the mechanical, controls, servos systems, and programming systems. Factors to be considered for high speed cut and add on the fly are discussed.

Demand in Aerospace for assembly systems utilizing industrial robots is rapidly increasing. Robotic systems can often be implemented for smaller, labor intensive products where work is performed from a single side (e.g. close out of skins to spars/ribs). To justify the costs of automation and to maximize build efficiency, the industry is striving toward “one-up” assembly, whereby the product is assembled one time - drilled, inspected, and ultimately fastened - without removal of components for deburring, cleaning, sealing, etc. To qualify this for production on The Boeing Company’s 787 moveable trailing edge (MTE) assemblies, the robotic systems required certain key capabilities to not only produce a quality process, but also verify quality via highly developed measurement systems.

The second generation of Electroimpact's ONCE robotic drilling system has been successfully deployed in production. The automated system for drilling and inspection of skins to substructure in trailing edge flaps comprises an off-the-shelf KUKA KR360 robot integrated with an Electroimpact process head, 7th axis linear rail, and roll-over assembly fixture. The process includes drilling up to 3/8″ in diameter holes, countersinking, and inspection of CFRP/AI/Ti stacks using a 20k rpm, ATC spindle. Automated vision feature recognition and auto-normalization capabilities ensure proper hole vector and location with verification of diameter, countersink depth, stack thickness, and drill thrust being measured in-process. Tailored nose pieces enable access to nearly 100% of the structure with flood coolant, compliant tip, and vacuum swarf extraction capability.

Fabrication and assembly of the majority of control surfaces for Boeing’s 777X airplane is completed at the Boeing Defense, Space and Security (BDS) site in St. Louis, Missouri. The former 777 airplane has been revamped to compete with affordability goals and contentious markets requiring cost-effective production technologies with high maturity and reliability. With tens of thousands of fasteners per shipset, the tasks of drilling, countersinking, hole inspection, and temporary fastener installation are automated. Additionally and wherever possible, blueprint fasteners are automatically installed. Initial production is supported by four (4) Electroimpact robotic systems embedded into a pulse-line production system requiring strategic processing and safeguarding solutions to manage several key layout, build and product flow constraints.

Low rate initial production of the 777X flight control surfaces and wing edges has been underway at the Boeing St. Louis site since early 2017. Drilling, inspection, and temporary fastening tasks are performed by automated multi-function robotic systems supplied by Electroimpact. On the heels of the successful implementation of the initial four (4) systems, Phases II and III are underway to meet increasing production demands with three (3) and four (4) new cells coming online, respectively. Assemblies are dedicated to particular cells for higher-rate production, while all systems are designed for commonality offering strategic backup capability. Safe operation and equipment density are optimized through the use of electronic safeguards. New time-saving process capabilities allow for one-up drilling, hole inspection, fastening, fastener inspection, and stem shaving.

Large diameter, tightly toleranced fastener patterns are commonplace in aerospace structures. Satisfactory generation of these holes is often challenging and can be further complicated by difficult or obstructed access. Bespoke tooling and drill jigs are typically used in conjunction with power feed units leading to a manual, inflexible, and expensive manufacturing process. For 777X flap production, Boeing and Electroimpact collaborated to create a novel, automated solution to generate the fastener holes for the main carrier fitting attachment pattern. Existing robotic automation used for skin to substructure assembly was modified to utilize extended length (up to 635mm), bearing-supported drill bar sub-assemblies. These Long Assembly Drills (LADs) had to be easily attached and detached by one operator, interface with the existing spindle(s), supply cutting lubricant, extract swarf on demand, and include a means for automatically locating datum features.