威廉希尔官方下载

SPI Pulsed Fiber Laser And Its Application In Metal Cutting

威廉希尔官方下载Feb 11, 2020

Introduction

Nanosecond pulsed fiber lasers are usually used for laser marking, but because the cost of nanosecond pulsed fiber lasers is low, compact, reliable and does not require frequent maintenance, it is also very suitable for evaporation cutting. By adopting designs such as MOPA (Master Amplifier Power Amplifier) that directly modulate the seed laser, we can obtain short pulses and relatively high peak power. These technologies have turned the laser into an effective processing tool for cutting metals.

As an alternative to a continuous-wave cutter, a pulsed fiber laser can be used in the multi-pass evaporation cutting process. The monitoring device controls the laser to pass back and forth through the cutting line, removing only a small amount of metal at a time, without the need for nozzles and assistance. gas. This technology provides a flexible, precise and reasonable solution. And this device is basically a simple laser marking system.

This cutting technology can be applied to a wide range of materials, from non-ferrous metals and non-ferrous metals to ceramics, polymer materials and even carbon-containing composites. The cutting speed can be easily changed. For thin metal plates, it can be less than 10mm / min. For thick materials, the cutting speed can be greater than 1mm / min. When used to cut thick metal, special techniques such as cutting line compensation or beam swing must be used to effectively expand the width of the cut. These speeds may be slow compared to traditional laser cutting, but for many applications, the low cost and flexibility of nanosecond pulsed fiber lasers is very attractive.

Experimental results show that all SM / HS / HM models of SPI lasers can achieve effective cutting, but the cutting characteristics of each machine will be slightly different, which is related to the choice of materials and the required output. Taking the narrow slit width as an example, an SM laser with a high-quality beam and a small spot is most suitable. For thicker materials, the HM type with a higher peak power and a larger size spot will be better.

Aluminum material

Pure aluminum and aluminum alloys are widely used, and some small and complex parts can be cut from thicker materials. (Figure 1) The finished surface does not have a great effect like drawing, and the polished part can also be cut very well. Parts up to 2mm thick can be cut and shaped like this, but the speed will be slower.

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Image1 Cutting samples include: 1.2mm aluminum sheet, 0.2mm tin steel sheet 0.5mm and 2mm polished aluminum.

Stainless steel

Stainless steel is a very widely used material. Especially in the medical industry, the requirements for cutting accuracy are very high. For 0.5mm thick 304 grade materials, a simple scanning system can be used to achieve a cutting speed greater than 20mm / min while achieving good cutting quality. However, using a 40W HM laser, equipped with a fixed cutting head and coaxial auxiliary gas, the cutting speed on 200μm stainless steel can reach more than 1.5m / min! (Image 2)

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Image 2 Processing of 200um thick stainless steel sheet with 40W HM speed

1.5m / min

Titanium material

Thin titanium plates are easy to cut. For engineering applications, care must be taken to ensure that edge oxidation does not affect the quality of the cut edges. However, for applications with less demanding technical functions, such as decorative jewellery, this process is ideal and can be combined with color marking.

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Image 3 Titanium craft jewelry 300um thick, using 20W HS laser cutting speed 1-2mm /s

Highly reflective material

Copper, brass, silver, and gold all have extremely high reflectance and electrical conductivity, so these materials are often considered very difficult to cut. High power density is required to start the cutting process, but cutting is easy with nanosecond fiber lasers.

Brass is generally considered to be a difficult material for laser cutting, and it is often used as an experimental material before cutting gold to test and study cutting parameters. As long as there is sufficient peak power, materials that are quite thick or even up to 1mm can be cut with a 20W HS laser, and the quality is very good. If a 40W HM laser is used, the maximum thickness that can be processed can reach 2mm. (Image 4)

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Image 4 is 0.8mm thick brass gear processed by 20W laser, takes 7 minutes

Many engineering applications require cutting copper, especially in the electrical and electronic fields, especially sheet metal materials. Although the material has high reflectivity and high conductivity, the high peak power coupled into the metal makes the cutting accuracy very high and no burrs (Figure 5). An emerging application is the copper cutting of precipitation tracks on PCB boards, as there are certain requirements for cutting conductive tracks on boards.

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Image 5 Copper sheet cutting using a 20W fiber laser

For example, precious metals such as silver and gold, we can use pulse laser to cut, because this technology can complete very complex shapes, and the material waste rate is very low, which is undoubtedly very attractive to jewelers. The picture below is a good quality, very gorgeous silver plate with a diameter of 20mm. It was cut with a 20W HS laser. (Image 6)

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Conclution

Nanosecond pulsed fiber lasers are very suitable for evaporative cutting. The above examples show that many metals can be cut by lasers, which also shows that such lasers are versatile.

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