Advantages and applications of high speed and efficient laser processing
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Unique advantages of laser processing
1. The thermal impact is very low. Compared with the traditional welding and cutting methods, laser processing does not need to generate high temperature, thus minimizing the material damage to the base metal and the coating;
2. The material deformation is very small, and a large amount of material deformation can be controlled within a few hundredths of a millimeter;
3. High-speed machining, for thinner stainless steel materials, the welding speed can reach 10 ~ 20m / min, there will be a response change for different materials and thickness;
4. The surface of the processed material will be very clean and smooth. Most of the steel, aluminum and alloy materials will not show obvious deformation or damage on the surface after laser processing, and the appearance and characteristics of the original materials are maintained to the greatest extent;
5. Unilateral processing, no need to touch, because the working principle of laser is non-contact beam focusing, so only one side needs to act on the material outside a certain distance;
6. No post processing required.
Laser welding
Welding can be subdivided into body welding and spare parts welding. For the body, the most common is to complete the body welding of the roof to the side and the door. Usually it is a 2-layer lap welding of galvanized steel, and sometimes there are 3 layers of welding requirements, and the length can reach 2~3m. In addition, because laser processing can easily weld materials of different thicknesses and grades, this advantage can reduce many additional processes, save a lot of cost and materials, so in more body-related welding processes, such as baffles, Panels, interior doors, seats and rockers have increasingly used lasers to replace traditional welding methods. In these weldings, the materials involved are mostly steel (uncoated low carbon steel or 10-20mm galvanized steel) and aluminum alloy (such as 5000 series aluminum magnesium alloy, 6000 series aluminum magnesium silicon alloy or 7000 series aluminum zinc alloy). ). It should be noted that in the welding process of galvanized steel, because the melting point of steel (1 500 ° C) and the melting point of zinc (800 ° C) are much different, it is easy to produce excess pores in actual operation, which becomes a confusion of many manufacturers. GSI professional application engineers have solved this difficulty after many researches and experiments. For aluminum alloys, because of the high reflective properties of aluminum, many manufacturers have encountered problems such as porosity and fracture in their applications. In this respect, GSI has also successfully added fillers (especially the 2000 to 6000 series). Techniques such as aluminum alloys and double spots overcome these problems.
In the automotive parts, laser welding applications are more extensive, common: ABS system components, airbag components, solenoids, batteries and fuel nozzles, etc., using GSI continuous modulation laser with super modulation function The high performance welding of the product provides the most suitable solution. Super modulation can multiply the output power of the laser in an instant to achieve the penetration and soldering effects that are not possible with conventional lasers. GSI's JK125P lasers are designed for high-precision soldering and micro-cutting for a variety of industrial applications.
laser cutting
Laser cutting is another major application of lasers other than soldering. The main features are:
1. Very thin slit width, straight trim and beautiful appearance;
2. The smallest heat affected zone near the trimming edge to achieve minimal workpiece deformation;
3. Elimination of excess material melting during acceleration or deceleration due to good control of the average output power;
4. There is no mechanical deformation;
5. Compared to the traditional cutting method, there is no wear of the cutting tool;
At present, in the field of automotive processing, engineering plastics, hydroformed tubes, etc. have a wide range of laser cutting applications.
Laser welding solutions for automotive airbag components
Here is a brief introduction to the laser welding solution provided by GSI Laser Division for a car airbag module in North America.
Oberg Industries (hereinafter referred to as "Oberg") is a manufacturer of precision stampings for the automotive, medical and aerospace industries, and is known for its high-precision finished parts. A customer in the automotive sector has told the company that another manufacturer's welding of certain airbag components has quality problems. This supplier uses traditional tungsten-arc welding (TIG) welding processes to ensure the necessary reliability.
Oberg uses its own unique professional stamping technology to improve the accuracy and quality of its components, but customers also want to provide complete and reliable welded tubes. So, Oberg began to consider the use of laser technology to achieve the above objectives. At its Sarver facility near Pittsburgh, Pennsylvania, Oberg conducted a welding test using a low-power pulsed YAG laser. Oberg's customers are very satisfied with the results of the test in terms of visual appearance and strength, but believe that the entire process is still too slow.
In view of this, Oberg asked the GSI Laser Division to help them see if they could improve their speed through their application lab analysis. In terms of its own requirements, Oberg needed a laser source that would not only support a welding speed of 50 mm/s but also meet the end customer's strength requirements.
The welded tube is a 1008 perforated carbon steel debris plate tube having a thickness of about 1.2 mm. Before welding, first punch holes in the plate, and then let the plate form a tube with a gap of about 1.5 mm, which is convenient for seam alignment and positioning. The quality standard for this process is to ensure that the surface and bottom are well-formed and that even if an oversized ball is forced through the filter tube, it will not affect the weld. The inspection is carried out in stages during the manufacturing process.
The original mission of the GSI Application Lab in Novi, Michigan, was to determine the precise laser source for the prototype part and the appropriate welding technique. After discussing with Oberg, it was found that although the 1kW continuous Nd:YAG laser can easily achieve a welding rate of 50mm/s, the project is not economical. From a budget perspective, a 500W laser is more suitable. The prototype part was successfully soldered in July 2006 using a JK501SM Nd:YAG laser that supports both continuous wave (CW) and Super ModulatedTM outputs. For the prototype part welding test, the actual pipe parts without holes are targeted. Different welding speeds and parameters were used to achieve different penetrations and to measure their strength.
The Super ModulatedTM output provides higher laser peak power with sine and square wave waveforms up to twice the rated laser power, while also achieving full laser rated average power. In this way, the welding speed is increased by 40%, and the heat consumed is much lower than the CW output alone.
In addition, Super ModulationTM significantly reduces the amount of laser energy scattered by the fumes above the weld pool during the welding process. The CW output will generate a large amount of soot at the weld after a few milliseconds from the start of welding. The soot is granular and will scatter, causing the beam to deviate from the focus, resulting in a larger weld width and reduced penetration.
When a periodic peak sine wave or square wave waveform is used, the laser energy of the super modulated laser can be emitted within a few milliseconds before the amount of soot reaches a certain scattering effect. During the modulation low energy cycle, the amount of soot quickly drops to near zero, and the laser source then begins the next duty cycle through the Super ModulatedTM output. This effect is produced regardless of the laser power level or beam quality. The cross-sections of CW, sine wave and square wave modulation clearly show the improvement in penetration.
To this end, Oberg chose the smoothest 500W CW welding method with a welding speed of 50mm/s, penetration penetration of 100%, a 100mm focusing lens and a focal diameter of 300mm. These initial parts are placed in a simple vise, clamped to the gap, and the protective argon gas is discharged through the side nozzles.
In 2006, as part of the design of the parts and the introduction of manufacturing tools, Oberg conducted more welding tests. In all cases, the parts were manually placed in the fixture and clamped to the gap with a vise, and the laser process was very consistent.
After the laser system arrived in Oberg to start laser welding, some problems occurred during the transformation of prototype welding into automated manufacturing welding. The gap in the butt weld is somewhat inconsistent due to component position and spring force problems. The design of the protective gas discharge in the case of fixed manufacturing has not been tested, and the welded parts have not passed the mechanical test of the customer. In order to achieve proper welding strength, the welding speed is reduced to 23 mm/s.
The GSI Application Engineering Design Center inspected the welding results and sent engineers to work with Oberg personnel to solve the process problems. As a result, they found that there were gaps in some of the fixed parts, and the difference in welding positions caused energy loss in the laser welding of the weld to the center. Increasing the focal length of the focus lens increases the focus size, thus avoiding the associated gap problem.
To increase the welding speed to 50mm/s and ensure the economics of the system, the laser parameters were changed to Square Wave Super ModulationTM. This speeds up the welding process and meets the 20% increase in focus size.
Finally, in order to achieve sufficient weld strength and toughness, the protective argon gas emissions from the welding fixture must be optimized to ensure that the oxygen content of the solder during the process and during the cooling process is extremely low.
Finally, to achieve a welding speed of 50 mm/s, a square wave super modulation technique can be used with a frequency of 300 Hz, a peak power of 900 W, a focal spot size of 360 mm, and a protective argon gas. Using Super ModulationTM technology with an average power of 500W allows the system to compensate for gap differences that are difficult to predict during project prototyping, while simultaneously designing components and processes with low-cost, moderate-power YAG laser technology.
After successful process design, Oberg's welded parts reached the required strength while power consumption was lower than estimated. By using a 500W continuous waveform laser with super-modulation, Oberg not only achieves the necessary speed requirements at low cost, but also ensures the welding speed and quality in the manufacturing process, solving all process tolerance problems. By using this system, it is estimated that Oberg can save about $100,000 in mechanical costs.
Oberg is very satisfied with the above results, which not only helps to win new business opportunities, but also enables it to introduce new manufacturing processes for new and existing customers.