In aerospace and aeronautical manufacturing, fiber lasers have revolutionized cutting techniques and now standing toe-to-toe with non-thermal methods, offering high quality cuts with minimal Heat Affected Zone (HAZ). In fact, modern fiber lasers drastically reduce material embrittlement and process components at speeds that far exceed machining and other non-thermal technologies.
5-Axis Laser Cutting for Aerospace Manufacturing
Technology is constantly pushing the limits to make the unimaginable a reality for aerospace manufacturing. It is an industry that does not accept “good enough” because only refined technology that push the boundaries of today can bring us into tomorrow.
This technology is ever evolving through science, engineering and profound creativity, but at the heart of this technology expansion are very basic elemental building blocks: aluminum, chromium, iron, carbon, titanium, nickel, cobalt and other special alloys.
Laser cutting brought the industry out of the world of hard tooling but initially lasers had limited use and came at a significant cost both monetarily and in productivity.
Utilizing lasers to cut these metals for aeronautical and astronautical industry use was at one time a pipedream, but now is a major contributing factor to delivering consistent repeatability with precision and quality, while minimizing scrap, optimizing workflow and reducing costs.
The reduction of Heat Affected Zone (HAZ) in aerospace manufacturing is one of the key points of this revolution and the advancement in laser cutting technology pierced through non-thermal technologies to deliver high-quality cuts with a laser beam featuring extremely minimal Heat Affected Zone (HAZ). In this article we will see a short overview of methods and techniques used to cut aerospace components made of aluminum, titanium, nickel and other special alloys with minimal Heat Affected Zone (HAZ).
What causes Heat Affected Zone (HAZ) in laser cut components?
Heat Affected Zone (HAZ) is something present in all mechanical parts processed with thermal cutting methods. We are not just referring to technologies widely recognized for their thermal impact on materials - even methods like electrical discharge machining (EDM) can produce a very thin Heat Affected Zone (HAZ) that is unacceptable for aerospace applications.
The problem is generated by the quantity of energy transferred in the area surrounding the cut and causes the cutting edge to become brittle and more prone to fractures as well as negatively affecting fatigue performance of the component being cut – this makes estimating the lifespan of the part impossible. The factors that amplify this area in the aerospace components depend on a correlation between the material, the laser source and technological characteristics as well as the assist gas.
As a result, a secondary process is always required to mechanically remove the affected material, with an increases in labor and operating costs depending on the thickness of the altered material to be eliminated. This paired with safety regulations for aerospace posed a low-capped contribution to advancements.
Laser source
Aluminum alloys have long been one of the most widely used metals for aerospace components due to their strength, lightness, corrosion and UV resistance.
In the early stages, industrial lasers were predominantly equipped with CO2 laser sources. The low absorption coefficient of aliminum for CO2 laser source wavelength and the limited power emitted by this technology, initially, made laser technology unrealistic for cutting aerospace components made from aluminum alloys.
It was only with the advent of modern fiber lasers that made this a reality.
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Modern fiber laser sources currently have the most suitable laser wavelength for aluminum alloys. This results in less reflected energy as well as a more efficient and effective cut.
In addition, a pulsed operation mode allows fiber lasers to mitigate the aluminum's high thermal conductivity, thereby minimizing heat transfer to nearby areas.
This is why fiber lasers are the ideal solution for cutting aluminum alloys – they significantly reduce Heat Affected Zone while enhancing the precision and quality of the cuts.
Laser cutting of die casting component.
Laser beam quality and concentration
Another key factor in reducing the Heat Affected Zone (HAZ) is the quality of the laser beam itself. This refers to how tightly the laser's power is focused on its central axis. Ideally, this concentration should resemble a Gaussian distribution, which ensures consistent irradiance across the beam. The more the power distribution is molded to this ideal shape, the higher the beam quality, leading to superior cutting performance.
Modern fiber laser sources, such as those utilized in LT-FREE 5-axis laser cutting systems ranging from 2 to 5 kW, are distinguished by their exceptional beam quality, featuring a remarkably low Beam Parameter Product (BPP) index, which ensures superior cutting performance.
In addition, advanced automatic focusing systems are utilized to further optimize the laser's energy distribution. These systems automatically adjust the focus of the laser beam based on the thickness and material of the component being cut.
BLM GROUP innovations like Active Focus, featured in our 5-axis laser cutting machines, are essential for achieving precise cuts in components formed through extrusion, die casting and bending processes, significantly reducing Heat Affected Zone.
Assist gas
The assist gas utilized for the cut plays a crucial role in the containment and reduction of Heat Affected Zone (HAZ). Using oxygen as an assist gas significantly increases the heat generated during the cutting process. When oxygen comes into contact with a metal at high temperatures, it triggers a strongly exothermic oxidation reaction, which contributes to the material's liquefaction.
When cutting aerospace components made from titanium and nickel alloys, this reaction would be particularly intense leading to poor cutting quality and a larger HAZ with the contamination of oxides within the crystalline structure.
In this case, the use of inert gases like nitrogen or argon is essential. These gases do not cause oxidation reactions, and therefore result in excellent edge quality and significantly reduce HAZ.
A recent alternative is to use compressed air as the assist gas in laser cutting. This method not only mitigates oxidation reactions but also provides a cost-effective solution by leveraging the most plentiful gas available.
The LT-FREE system incorporates a specialized feature called Active Air Cutting. This scalable solution enhances efficiency and cutting quality, accommodating various levels of autonomy in the cutting process. The machine is equipped with different gas lines and autonomously selects the gas needed via an automatic system.
Aerospace fuel line.
5-axis laser cutting machines for Aerospace manufacturing
In this feature, we have explored how technological advancements in laser technology have firmly positioned lasers as a fundamental pillar of next-generation aerospace and aeronautical manufacturing.
Paired with advancements in fiber laser technology, the complexity of thin profiles in aerospace requires a laser cutting head that can rotate around 3-dimensional objects with total freedom. The development of 5-Axis laser cutting technology was the final piece to complete the puzzle.
The LT-FREE 5-axis laser cutting system from BLM GROUP is an effective solution to reduce Heat Affected Zone (HAZ) in aerospace manufacturing. This cutting-edge technology not only boasts undeniable technological advancements but also delivers unparalleled precision and quality in the laser cutting of intricate three-dimensional components such as bent tubes, hydroformed parts and die-cast elements.
In an industry that is in constant evolution, LT-FREE meets the escalating demands for automation and productivity, making it an essential asset for modern aerospace manufacturing.
LT-FREE - BLM GROUP 5-axis laser cutting system