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Analysis: fiber laser welding bring industry to more flexibility
- May 12, 2016 -

Analysis: fiber laser welding bring industry to more flexibility

Bring new capabilities and greater flexibility in this area for more fiber laser welding metals and Kim, which makes many of the leading manufacturers of this vote more attention, particularly in the aerospace field. The Research and Development is the development and fiber laser welding 2D and 3D parts in processes and systems, including low, medium and high-power CW and QCW fiber lasers.

Application of metals and alloys has been confirmed, for example, 304 stainless steel, titanium (Ti-6Al-4V titanium alloy and Ti-6Al-2Sn-4Zr-6Mo titanium) and high-temperature nickel-based alloys, including Inconel625, Inconel718 and HastelloyX other high-temperature alloys. With its kilowatt average power, wavelength of 1μm with a high brightness (beam quality), high-power CW and QCW fiber lasers can provide a new functionality and flexibility of the laser light source.
Compared to the CO2 laser welding, the advantages of 1μm wavelength fiber lasers include: fiber-optic cable without the need to rotate the mirror, which makes the beam delivery easier; was more absorbed by the metal, especially those well-conductive material, such as aluminum, and is formed on the weld pool plasma plume absorb even less; copper. And high power Nd: YAG laser compared to higher brightness fiber laser, which means that the laser beam can be focused to a smaller desired dimensions, which would lead to higher power density. These factors contribute to higher than other laser sources penetration and faster welding speed at the same power. It will also contribute to more stable welding process in a wide variety of metals and alloys.
In the past 33 years, Laserdyne company installed many applications of laser welding machine used in the aerospace (engine and airframe), automotive, electronics, fluid couplings, medical equipment, the use of CO2 and Nd: YAG lasers as a laser light source, and more recently using a fiber laser. A wealth of experience allow the company to fully Laserdyne flexible use of these lasers to weld high value-added components.

Welding of metals and alloys
By Prima Power Laserdyne welding equipment under test in a range of different laser parameters and protection gas conditions. Use metallographic analysis (cross-section) and X-ray techniques to laser (spot size, laser power, etc.) and processing parameters (type of protection gas, gas flow rate, aspiration method, welding speed, focal position, etc.) and the resulting weld the relationship between the shape and structure. For example, the test will lead to clarify the factors that produce weld porosity, and how to get non-porous welds. These experiments also illustrate the effect of laser welding and machining parameters on the shape and structure.

Surrounding the recent laser welding alloys for aerospace applications conducted the most comprehensive study. For these materials, the most important challenge is to connect the extremely strict requirements, the weld can not have any cracks or pores. We must ensure the correct shape of the weld to ensure that at high temperatures also have good mechanical properties. Test proved, CW and QCW fiber laser welding capability aerospace alloys.

However, the challenge lies in setting robust performance laser machining parameters, which means to ensure continuing stability of the weld quality. Laserdyne for all aerospace alloy welding applications and the development of laser processing parameters. Welding tests showed that the quality of welding can not help a single parameter control, but to influence the weld quality by combining a series of laser and process parameters. These studies also showed that in a series of nickel-based and titanium-based alloys can be relatively easily obtained no cracks and pores in the weld.

Welding test also includes a filler wire welding. Certain alloys and connecting dissimilar materials require additional fill material to control the structure of the weld metal, to avoid cracks, thereby ensuring desired mechanical properties. In other cases, the weld filler metal is used to control the geometry, so that the surface of the weld fusion zone slight protrusion (reinforcement). Filling materials are also used to make laser welded butt joint structure to match or even bad mismatch. Laser filler wire welding process is influenced by many parameters, laser parameters and many filler wire determines the quality of the resulting welds. By the welding tests, all the important parameters and adding filler relevant obtained optimization, this will ensure the quality of the weld.

Bring new system functions

A significant hardware developments is a new nozzle design with a cross-focusing lens group, it can ensure that the third-generation Beam Director Laserdyne system (called BD3Y) has a compact form. Cross nozzle design can provide a high flow rate of gas barrier protection to prevent sliding metal contamination spark weld region of the lens. The key to this design is that cross contamination can be avoided or nozzle interference shielding gas welding. Cross nozzles may affect the complete protection aspirated gas equipment, including welding coaxial gas nozzle tip.
Protective gas liner will provide a controlled weld fusion zone area, and where the material is not cooled to ambient atmospheric effects so far. This is very important for those of welding material on the environment atmospheric oxygen and nitrogen has a strong affinity for, such as titanium. Another important benefit of the focus lens / cover gas component is designed to bring the laser welding, the focusing lens can be embedded quickly adjust these components, in order to change the beam spot size.

Strengthen controls in order to obtain high-quality welds
It has been demonstrated using LaserdyneS94P control can achieve new laser control functions, especially the laser power ramping control and sub-millisecond laser pulse shaping, which will bring a more consistent, high-quality welds. It extends the range of materials laser welding applications, thereby increasing the flexibility of the laser welding system. Pulse shaping has been shown to effectively control the shape and structure of the weld. This is mainly formed by controlling welds and weld fusion zone and heat affected zone during cooling temperature distribution to achieve.

For example, by providing a lower pulse amplitude after the initial part of the pulse to control the cooling of the alloy, which along with the laser fusion process of rapid cooling will gradually harden. Another example is the use of those materials reflected laser beam pulse shaping (the leading edge portion to maintain a high pulse amplitude). Rapid heating surface will increase the absorption of the laser beam to achieve a more consistent process.

All of these features have been standardized, and can implement these features in the company's 3-axis and 7-axis systems product line. Is progressing on these fiber laser system has only just begun: With the addition of new users, there is no doubt their unique application and experience will help the industry increase productivity, improve quality, and to achieve greater efficiency.