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Why not choose inferior laser cutting head protective lens?

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The cutting heads of laser cutting machines are used in very harsh environments. In order to protect the internal optical path and core components from damage, the cutting head needs to be equipped with a protective lens. The cleanliness of the protective lens directly affects the processing performance and quality of the laser cutting machine. If the lens is dirty, it will not only affect the cutting effect and efficiency, but also cause the internal parts of the cutting head and laser output head to burn out. Therefore, it is necessary to choose a protective lens with good material, high light transmittance, and small thermal expansion coefficient. When the lens becomes dirty during processing, the lens needs to be cleaned or replaced. If glass lenses are used during processing, they can be cleaned with a special detergent, and then rinsed with clean water. However, the laser cutting machine is a precision instrument, and it can be easily damaged if ordinary cleaning agents are used. Therefore, proper surface preparation of the lenses must be performed prior to cleaning. In addition, in laser cutting machines, glass lenses cannot withstand high-intensity cutting operations for a long time and must be replaced in time. Edge quality also affects optical performance due to the amount of spatter and debris generated during edge trimming.

The processing of protective lenses has special technological requirements. In order to reduce costs, low-quality protective lenses are made of ordinary materials, resulting in poor light transmittance and heat resistance, easy to break, and unable to withstand the penetration of laser light. Powder particles can contaminate the entire cutting head, damaging core high-value components including focusing lenses and sensors. In addition, the maintenance cost of the cutting head is very high, which will eventually delay the production process and cause greater economic losses. Therefore, it is recommended that customers purchase laser accessories from the official channels of the manufacturer to avoid losses! The service life of a laser cutting machine depends on factors such as beam quality, laser output power, material and cooling system. Laser beam quality is the foundation of laser processing and the most used factor in laser processing. If the beam quality is not good, the cutting head will not be able to perform its due function, therefore, the beam quality must be strictly controlled. There are many types of lasers, generally speaking, fiber lasers with power above 500W have good beam quality.

The following are the adverse effects that poor-quality protective glasses can easily cause:

1. The thermal lens effect causes the focus drift of the cutting head

Poor quality protective lenses will increase the absorption rate of the laser. After a long time of continuous exposure, the temperature will rise and cause thermal deformation, which will cause thermal lens effect and cause the focus of the cutting head to drift. The higher the power, the processing of highly reflective materials, the faster the thermal expansion of optical components, the more obvious the thermal lens.

(1) When cutting stainless steel, the focus drift of the thermal lens effect will lead to inconsistent cutting section effects and more and more slag.

(2) When cutting carbon steel, the thermal lens effect will cause more and more slag at the bottom.

If the optical quality of the lens is poor, the processed optical element will be thermally deformed, which will affect the working accuracy of the laser. For ordinary steel sheets, the temperature of the optical element is determined by the heating and cooling of the material during processing. In the actual processing process, plasma is usually used to cut carbon steel (for example: cutting carbon steel because of its relatively low reflectivity). During the cutting process, the energy of the laser will gradually accumulate on the carbon steel and cause thermal stress and deformation. With the increase of cutting speed and processing power, the laser intensity is getting higher and higher, and the cutting area will become smaller and clearer.

2. Protective lens burn/burn through

Inferior protective lenses have poor ability to block dust and splash during processing, and are prone to burn spots; for a 10,000-watt ultra-high-power processing head, protective lenses must be carefully selected, and poor-quality protective lenses are under the action of a 10,000-watt laser If it is serious, it will directly cause the lens to burn through, which is determined by the material characteristics of the protective lens itself. During the use of the protective lens, its main function is to block dust, splash and protect the eyes and face of the staff. If the material of the protective lens itself is poor and the process is unqualified (such as electroplating, coating peeling, etc.), it is easy to cause damage to the lens. burn through.

3. Focus lens burn point

If the burnt-through protective mirror is not found in time and the optical processing is continued, the cutting will produce particle soot, which will rise and pollute the mounting components, sealing ring and the lower surface of the focusing mirror, and will also cause spots on the surface of the burning focusing lens. A mirror module is required for deep cleaning, replacement of a complete set of mounting components and focusing. A mirror module generally refers to a module with multiple optical elements. When the focusing lens adopts multiple sets of optical devices, the number of lenses can be determined according to its needs, but in most cases, a combination of three groups is selected. If multiple optical devices are used to make a set of lens groups in different positions, then there are many factors to be considered. When using high-quality mirror clamps, attention should be paid to the safety and scratch resistance of the focusing lens, in addition to the problems mentioned above In addition, there are many common mistakes that can result in burn marks on the lens.

4. The laser output head is burnt out

For 10,000-watt laser equipment, once the protective mirror burns through, it is easy to burn the collimating and focusing lens module inside the cutting head immediately under the action of 10,000-watt ultra-high power. In the worst case, when the internal optical components of the cutting head are damaged, the optical path will be abnormal, and the returning light will cause the window of the laser fiber output head to heat abnormally, and eventually the QBH or LOE crystal will be burned out. The entire laser output head needs to be replaced.

At the same time, the protective glasses also have a certain impact on the quality of the product. The protective glasses need to be well matched with the equipment, otherwise it will cause the equipment to malfunction and affect the normal operation; the protective glasses are precision electronic accessories. If there is a quality problem, it will directly cause Device performance degrades. Therefore, in order to ensure the normal use and stable operation of the cutting head equipment, it is necessary to purchase products produced by regular manufacturers when purchasing protective glasses.