Growth is driven by several factors, including the steady increase in air traffic, the development of the space economy and, especially in recent years, rising demand for defense applications. Aerospace is a frontier sector, constantly aimed at pushing beyond the limits of current human and technological capabilities.
This translates into extremely stringent requirements in terms of quality and reliability, which encourage the development of new materials, processes and technological solutions.
Tube bending in the aerospace sector
As with all mechanical components used in aircraft, rockets, helicopters, drones, etc., tubular parts, used both for fluid transport and as structural elements, must combine mechanical strength, reliability and the lowest possible weight.
They are therefore thin-walled tubes made from rigid, lightweight materials such as special titanium alloys, aluminum and stainless steels. Their characteristics, together with the extremely high-quality standards required by the prime contractors in this sector, make bending an extremely delicate process that requires a high level of technology.
The successful execution of a bend involves multiple aspects, among which the most important are the ability to ensure the geometric precision of the part, the high quality of the surface finish, and the micrometric control of the tube thin-out. Finally, given the high cost of the materials used, it is absolutely necessary for material waste to be close to zero.
Another technology increasingly used in the aerospace sector for both cutting and welding is laser technology.
Geometric precision of the bent tube
In the aerospace sector, final part precision is an essential requirement, but the real competitive advantage lies in achieving the required level of accuracy with the lowest possible number of rejects. This aspect is crucial both due to the extremely high cost of the materials being processed and the extremely small production batch sizes, which in some cases may be limited to just a few units per year.
In this scenario, the wide range of BLM GROUP tube bending machines can make a difference: fully electric machines equipped with state-of-the-art drives, capable of ensuring centesimal axis precision and perfect control of part deformation.
One of the key elements is software
VGPNext: the BLM GROUP tube bending programming software, saves all bending parameters together with the part program and automatically estimates elongation and springback, significantly reducing the number of trials and scrap needed to obtain the correct part. In combination with quick tooling change systems, it simplifies production changeovers, reduces the margin of error and helps maintain high levels of precision and repeatability. In this way, it is possible to fully meet the required tolerances in terms of ovalization, bend geometry and process capability Cpk.
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Outer radius (extrados) as a critical factor for aerospace part quality
The extrados of a bent tube is the outer radius of the bend, that is, the area of material most subjected to stretching during the bending process. In tubes intended for the aerospace sector, the integrity of this area is particularly critical due to the high stiffness of the materials used and the reduced wall thickness.
Prime contractors in fact require extremely low percentages of extrados thinning tolerances that generally put manufacturers under significant strain. To limit the thinning phenomenon, several solutions are possible, which usually require state-of-the-art tube bending machines capable of modulating every component of the tooling in contact with the tube.
An equally important role is played by the mandrel: in aerospace applications, multi-ball mandrels with optimized lubrication are normally used to ensure maximum internal support of the tube during deformation.
Surface finish of the bend
The surface finish, both internal and external, of a bent tube for aerospace applications is a critical parameter. Due to the reduced wall thickness and particularly severe operating conditions, vibrations, high temperatures, and pressure to which tubes may be subjected, any surface defect can trigger cracks and failures, with direct safety consequences.
For this reason, prime contractors require extremely tight roughness tolerances and the absence of clamping marks, scratches, and dents, imposing very strict limits on their depth.
BLM GROUP provides aerospace manufacturers with state-of-the-art tube bending machines: fully electric machines that integrate specific functions for precise material handling during bending. Among these are the electric control of all tooling components and the modular clamping torque, which allow dynamic adjustment of the forces applied to the tube.
In parallel, in more delicate cases, special-material tooling can be used to promote tube sliding without leaving scratches or dents on its surface.
The goal is generally to achieve a surface finish in which any possible defect is imperceptible to the touch or when passing a fingernail over the tube.
Conclusions
In the aerospace sector, where precision, quality and reliability are essential, tube bending requires advanced technologies that can deliver the desired result with the lowest possible number of rejects and trials.
BLM GROUP All-Electric tube bending machines enable full control of the bending process and simplify production start-up thanks to the complete absence of manual adjustments and to VGPNext, a powerful and intuitive programming software supported by artificial intelligence algorithms. The result is higher production efficiency, elimination of scrap and the ability to meet the most stringent tolerances required by the industry.
