As the civil aviation industry ramps up production of single-aisle aircraft, to meet the ever-increasing demand, automation continues to be a key enabler. Beyond simply increasing production rate, flexible automation is seen as a way to reduce machine downtime and costs. Serial industrial robots are increasingly being used both to replace both bespoke gantry automation systems and human operations. Since 2010, Airbus has increased A320 production volume from 34 aircraft per month to 60. This increase in volume is set to continue toward a rate of perhaps 100 aircraft within a few years. This trend is mirrored at Boeing,with 737 production rates following a similar course, despite a slight setback due to the recent global grounding of the 737 MAX.
Airlines spend about three times as much money on fuel as they do on purchasing aircraft. Reduced weight and fuel burn are, therefore, usually more important considerations than the price of an aircraft. This means that design trade-offs will always prioritize performance over ease of manufacture, making the automation of aircraft production much more challenging than in other industries.
Highly accurate and reliable bespoke gantry systems have dominated automation in aircraft manufacturing for many years. However, they are not without their issues. These huge machines represent a single point of failure that can stop production for long periods when something does go wrong. They also operate in dedicated cells where nothing else can be done on a structure.Industrial robots offer the possibility of using multiple off-the-shelf machines that work on a structure at the same time as human workers. These robots can be easily replaced when they break down, allowing relatively uninterrupted production. The faulty robot can then be repaired remotely before returning to the production line.
We recently featured Loxin’s multifunctional robot accurate drilling head (ADH), which enables a robot to drill a hole in the fuselage panel, mill a countersink for the rivet head, vacuum up the dust, apply sealant, and set the rivet. Now Airbus has unveiled its next-generation automated assembly line in Hamburg, which combines this technology with other advanced solutions in digital automation. The key components are high-accuracy robotic automation of the drilling and filling used to join aircraft structures, with a new concept for factory logistics that automates the flow of components and product around the factory.
The Hamburg structure assembly facility joins single fuselage shells into cylindrical sections and then performs full assembly of these sections into aircraft fuselages. The fuselages are equipped with electrical and mechanical systems before being shipped to final assembly lines in France, Germany, China and the U.S.
“By embracing some of the latest technologies and processes, Airbus has begun its journey to set new standards in A320 Family production. This new fuselage structure assembly line is an essential enabler for the A320 Family ramp-up. Increasing the level of automation and robotics enables faster, more efficient manufacturing while keeping our prime focus on quality. Given the enormous success of the A320 Family and the order backlog, we are taking the necessary steps to ensure our production system can match the excellence of our products and that we are able to satisfy our customers’ needs for our single-aisle aircraft,” said Michael Schoellhorn, Airbus chief operating officer.
High Accuracy Automation
Robotic automation systems are used to “drill and fill.” This has been a key goal for aerospace automation for many years, due to the huge amount of work involved in drilling thousands of holes and installing rivets in them. The main obstacle has been achieving the required 0.2mm positional accuracy across the large panels.
Aircraft structures arrive in assembly without predrilled holes. The thin flexible panels and stiffening components are clamped into jigs, which control the dimensional tolerances. It is only after this stage that holes are drilled through the assembly, sealant is applied to the holes, and rivets are fitted to join the structure. Two types of robot are used to perform these rules within the new A320 fuselage assembly line.
The first stage of the assembly involves joining curved panels longitudinally to form cylindrical sections of fuselage. There are eight “Flextrack” robots, essentially small gantry machines on tracks, which crawl along these joints, drilling and countersinking holes for rows of fasteners. Each longitudinal joint requires 1,100 to 2,400 holes.
The next stage is to joint these cylindrical sections together to form the fuselage. 7-axis robots are used to create these orbital joints, with multifunction end effectors that are able to drill, countersink, apply sealant, and insert fasteners. KUKA Systems has integrated standard KUKA robots with linear motion slideways to greatly increase the working volume of these robots. Each orbital joint requires 3,000 rivets, and 12 of these robots are used to perform this process.
Advanced Factory Logistics
Perhaps even more significant than the use of industrial robots is the radical solutions to logistics implemented in the A320 fuselage assembly line. This combines a number of concepts, with most of the logistics carried out overhead to maintain a clean floor environment.
The curved panels, or “shells,” are delivered into the first stage of assembly using an automated system of gantry cranes. This works like an inverted railway system, with panels hanging from a network of rails that have junctions, points and turntables to direct the components around the factory.
The push to keep logistics overhead and maintain the clean floor environment is taken further with a separated logistics level above the main factory floor and a pneumatic tube transport system for delivery of small components such as rivets and containers of sealant.
The large fuselage sections and the completed assembly are moved around the factory using automated guided vehicles (AGVs) as well as a large gantry crane.
This factory is finally bringing together many of the automation solutions that have been talked about and in development over the last 20 years. If you want to see the future of aerospace structural assembly, then take a look at the official video of the plant in operation available from Airbus.