Ultra-high-power fiber laser can achieve fast and high-quality cutting of thick plates, including using air as an auxiliary gas to cut stainless steel, and many advantages over other cutting solutions.
In recent years, ultra-high-power (UHP) fiber lasers with power ranging from 10kW to 40kW have been rapidly applied to the cutting market, and the higher laser power used for cutting applications is expected to continue to increase.
We will demonstrate the effect of applying cutting in this power range and discuss the main factors driving the application of ultra-high power fiber lasers: significant productivity advantages, improved cut quality and the ability to cut to the limit thickness (e.g. example, as shown in this article, cutting 230 mm thick stainless steel at a power of 40 kW).
In this article, the power of ultra-high-power lasers is defined as lasers with a power greater than 10kW. They enable new process methods to promote the expansion of laser cutting into new markets (e.g. using air as an assist gas to cut stainless steel up to 50mm thick at speeds 4 times faster than high-speed plasma cutting). power).
Application results show that ultra-high power lasers are changing the way stainless steel is cut, using air cutting technology instead of nitrogen and oxygen cutting technology to achieve economical, high-quality and high-quality cutting. speed.
Development trend in 6 years: The highest laser power used for cutting applications
(a) Air cutting of 28mm thick carbon steel at 4.5m/min (177ipm) with IPG40 KW YLS laser;
(b) Air cutting of 40 mm thick stainless steel at 2.3 m/min (90 ipm) with YLS IPG40 kW laser;
(c) Nitrogen cutting of stainless steel profiles from 3 to 25 mm thick with a YLS-ECO IPG30 kW laser;
(d) Cutting 30 mm thick carbon steel with oxygen at 15 kW.
In continuous wave (CW) full speed cutting mode, 20 kW of slag-free air is used to cut 20 mm thick carbon steel, 40 kW of slag-free air is used to cut 30 mm thick carbon steel, and 40 kW of slag-free air is used to cut 40 mm thick carbon steel (see Figure 2 and Figure 5 above). For cutting stainless steel, it is easier to achieve a slag-free effect, so the maximum cutting thickness is thicker than that of carbon steel (see Figure 5b and Figure 5c).
For continuous cutting with nitrogen and air, only a certain thickness can achieve slag-free cutting and good cutting surface at any power. Beyond a certain thickness, pulsed cutting (speed less than continuous) must be used to obtain qualified quality; otherwise, the laser power must be increased.
Typically, a cutting speed of less than 2 m/min means that the laser power is insufficient in continuous mode to obtain the best cutting quality.
For oxygen cutting of carbon steel, increasing the power will increase the maximum cut thickness while ensuring a “smooth cutting surface”. For example, the maximum cutting thickness at 4 kW is about 6-8 mm, while the maximum cutting thickness at 15 kW is 30 mm. Figure 5d shows a 30 mm thick carbon steel sample cut with a 15 kW laser.
Faster, cleaner piercing
By using the high peak power of the ultra-high power laser in pulse mode, thick metals can be drilled quickly with less spatter. Drilling time for 16mm stainless steel has been greatly reduced from >1 second at 6kW to 0.5 seconds at 10kW and 0.1 seconds at 20kW.
In practical applications, drilling times ≤0.1 seconds are generally considered “instantaneous”. The higher peak power increases the depth-to-width ratio of the weld pool, which allows for faster bridging of thickness with less lateral melting. The reduction in lateral melting of the material also minimizes spatter on the top surface.
Competitive Advantages of Ultra-High Power Laser Cutting
Over the past six years, several technological developments have driven improved laser cutting performance, including:
- Determine the required focal spot size by selecting multiple collimators or multicore fibers;
- High-speed rotating beams that improve the efficiency and quality of processing certain metals;
- High peak power continuous lasers for faster, cleaner complex drilling/cutting;
- Ultra-high power lasers.
Although the needs of different industries are different and all enabling technologies are used in specific areas, ultra-high power laser cutting is a leading technology trend that drives the improvement of laser cutting performance.
This is evidenced by the widespread adoption of ultra-high power lasers in laser cutting machines around the world.
As more and more application engineers adopt ultra-high power lasers, they understand that the production and quality benefits of ultra-high power cutting machines are multifaceted and outweigh those of lower power laser technologies with less complexity.
Ultra-high-power lasers have significant advantages in thickness cutting, quality and economics for thick plate cutting, especially at 15kW and higher powers, making them more competitive than high-current plasma cutting machines.
Comparative tests show that for stainless steel up to 50 mm thick, a 20 kW fiber laser is 1.5-2.5 times faster than a high current (300A) plasma cutting machine. For carbon steel, it also shows that the cutting speed for thicknesses up to 15 mm is twice as fast.
Calculations show that for 15mm thick carbon steel, the total cutting cost per meter using a 20kW laser is about half that using plasma.
Due to its faster cutting speed for 12 to 50 mm thick stainless steel sections and 12 to 30 mm thick low carbon steel sections when compared to high power plasma cutting, the use of a 40 kW for these materials produces an even greater difference in productivity.
Adopting ultra-high power lasers
Compared to low-power lasers and other cutting processes (such as plasma cutting), the main driving force for adopting ultra-high-power lasers for cutting is higher productivity and lower cutting costs per part.
Speed gains from using ultra-high power lasers provide economies of scale for manufacturers; for example, increasing power from 30 kW to 40 kW increases cutting speed by 66%.
Ultra-high power lasers enable fast, high-quality cutting of carbon steel, which is more advantageous than slower oxygen cutting and more expensive nitrogen cutting. In our tests, using 40 kW air cutting to cut carbon steel up to 50 mm thick was three to four times faster than high-power plasma cutting.
Ultra-high power lasers make laser cutting more competitive in many other ways. For example, increasing the thickness and quality of the cut (materials up to 230 mm thick can be cut), reducing or eliminating post-processing costs (reducing slag suspension as much as possible), reducing the footprint and production costs installation, reducing labor requirements and improving drilling quality and yield.
As the power and efficiency of ultra-high power lasers continue to improve, these advantages will become even more apparent – increasing their ability to quickly and economically change cutting applications across different industries.
