As with other industries, aerospace manufacturers are challenged to find new ways to support higher throughput while lowering the cost of production. However, this market segment has unique manufacturing challenges. Airplanes are complex, highly engineered machines that require components made with high accuracy. Production volumes are relatively low and there is large product variability.
Many aircraft components are made from aluminum alloys used for their strength, corrosion resistance and lightweight properties. These high-strength alloys are costly and difficult to work with. What’s more, the aerospace industry relies heavily on manual labor, which makes the manufacturing process time-intensive and prone to human error, resulting in wasted resources and a high cost per part.
Automation in the form of advanced machinery, robotics and material handling is helping the industry overcome these challenges. The process of bending – one of the most labor-intensive operations in metalworking – is now more easily automated. Especially with parts such as the aircraft fuselage and wing sub-assemblies, automated bending equipment in an extra-large format can more effectively handle the production of the largest of aircraft components.
This article looks at the current state of bending XXL parts and the special needs of aerospace applications (in particular, aircraft components). Also covered is unique synchronized adaptive bending technology that automates XXL bending to ensure consistently accurate parts manufactured in significantly less time – reducing production time 50 percent or more.
Today’s bending
Bending large, heavy parts and profiles is a challenge for a number of industries – in the manufacture of yellow goods, wind power systems, lighting poles and telescopic cranes. The demands for bending XXL aircraft components are similar but further complicated by the rigorous demands of the industry.
For instance, many aerospace components feature pocket-shaped, thin-walled structures that are used to lower the overall weight of the end product. Because bending these structures involves large variations in material thickness, which affects component quality and durability, parts are first formed and pockets are later milled as a secondary process.
Machining thin-walled parts has its own challenges, so advanced 3-D CNC milling equipment is often required to achieve precision results. This can be a slow and costly process that adds to manufacturing time.
Bending of XXL parts typically involves:
- Workpiece handling: An overhead crane is used to transport the material and position it on the front support arms of the press brake. Most fabricators handling large parts use front supports on guide rails to help position the workpiece along the length of the machine. Positioning in this way is usually slow, inefficient and potentially dangerous.
- Defining bend lines: Without offline programming software, bend lines are determined manually. This process is often painstakingly accomplished with a basic measuring tape and chalk.
- Material consideration: Heavy-duty bending operations commonly use special high-tensile steels to reduce the weight of the end product. In the aerospace industry, aluminum alloys are preferred for their high strength-to-weight ratio. These alloys reduce the weight of an aircraft significantly, which, in turn, lowers fuel consumption. The extreme strength of these alloys impacts bendability. Thickness and bend radius, formability of the alloys and the amount of elongation that can occur are all factors that need to be considered. Working with aluminum alloys requires expertise and the machine and tooling must be optimized for aluminum.
- Tooling setup: CNC V-dies and other special tooling are frequently required for bending. Depending on the part profile and the number of bend radiuses, tools may need to be changed during the production process. Considering a 12-m or 14-m press brake, tooling changeover can take several hours.
- Bending and correction: The only way to compensate for accumulated error and ensure an accurate part is to bend in steps, making program adjustments as needed along the way. If it’s necessary to re-bend on the bend line, the operator will need to reposition the part(manually or using a crane). This work demands an experienced operator and is a trial-and-error method fraught with the possibility of error.
Extra-large bending
Because of the scale and size of aircraft components, the aerospace industry has been conservative in adopting automation, but next-generation synchronized adaptive bending technology in an extra-large format press brake is changing the current state, improving XXL bending for aircraft manufacturing.
Adaptive bending is a modern manufacturing technique that provides real-time part angle sensing and real-time error correction to ensure the accuracy of the formed part. Synchronized adaptive bending for XXL parts takes this a step further as it also handles, manipulates and positions the workpiece during the bending cycle. LVD’s Synchro-Form uses modules (gauge/push devices), sheet supports and magnetic or pneumatic grippers to automatically position and guide the workpiece. Each module can handle 200 kg. Using three front modules and three back modules, the system can handle a maximum sheet weight of 600 kg.
The synchronized adaptive bending system automatically positions the part, automatically performs the bend cycle, and automatically measures and compensates for accumulated error with no operator intervention needed. Variations are not accumulated but rather compensated with each bend. So even after multiple consecutive bends, the desired angle is achieved. Offline programming software is used to program parts, eliminating manual programming at the machine.
This technology reduces the direct cost of the XXL part by reducing manual operations, increases throughput by automating the bending process and ensuring part accuracy, and makes for a safer production environment.
Standard tooling can be used for most applications, eliminating the need for costly CNC V-dies and reducing tooling setup time. This is possible because step bending is used to bend various radiuses, reducing the number of special tools needed for the job.
For aerospace components, tooling is a special consideration. In the case of the synchronized adaptive bending system shown on page XX, a CNC-controlled adjustable punch was developed to handle the bending of components featuring pocket-shaped, thin-walled structures. The CNC-controlled adjustable tooling shown has 210 CNC-controlled axes that regulate the depth of the punch every 2 in. in order to bend in a straight line.
This special tooling is able to optimize the bending of aluminum alloy and allows the workpiece to be first milled and then formed. Milling out the material first is faster and less costly, and allows the use of a more basic milling machine.
Adaptive advantages
Synchronized adaptive bending offers a number of advantages for aerospace. With more capacity and reduced manual operations, the manufacturing cost per unit is lower. Using synchronized adaptive bending, parts are produced faster with greater efficiency and accuracy. The accuracy of bending eliminates scrap and shortens the manufacturing process – manufacturing time is not impacted by human error or process variability. Automation reduces the need for skilled labor, so workers can be reallocated to focus on production oversight or other jobs away from manual tasks.
Automating the bending process can significantly increase throughput and ensures consistent part accuracy. For example, a workpiece 14 m long with 37 bends can be formed in approximately 32 min. A manual process would take up to 1.5 hours. Downtime for manual bend compensation/correction and tool changeover is reduced, trial-and-error bending is eliminated and there is better utilization of capital equipment.
The intensive manual work in XXL bending comes with health and safety risks to the worker. The synchronized adaptive bending system eliminates the need for workers to pick up or position heavy materials or perform other potentially dangerous tasks associated with heavy machinery and XXL workpieces. What it would take two or more workers to perform, the system can accomplish on its own.
For the bending of XXL aircraft components, synchronized adaptive bending technology is a way for aerospace manufacturers to overcome their toughest production challenges and meet specialized manufacturing needs with a lower cost of production. This automated bending technology expands production capacity and achieves the high accuracy requirements of modern aerospace components while keeping worker health and safety in mind.
