Views: 8 Author: DURMAPRESS Publish Time: 2021-07-07 Origin: DURMAPRESS
While the use of lasers in cutting, drilling and welding is well known, its applications in industrial cleaning are relatively new and have wide unexplored scope.
CL-500 Laser cleaning machine applications stem from the market need for a non-toxic, non-abrasive cleaning method that can be used as an alternative to previously used chemical cleaning, manual cleaning, and abrasive jet cleaning methods.
Advantages of CL-300 Laser cleaning machine
The main problems of traditional cleaning methods include: negative impact on the environment and wear on the substrate. Sand blasting system produces a large amount of waste, and will damage the fine surface of the substrate; Using chemical solvents creates potentially dangerous steam and liquid waste.
The shortcomings of traditional cleaning methods promote the application of laser technology in the field of surface cleaning. Due to the advantages of laser cleaning, it has become the most effective method to remove unwanted material from the material surface.
Currently, pulsed CL-100 Laser cleaning machine and coating systems are used in a wide range of applications, from ablation to remove vulcanization residues from tire molds and sculpted surfaces, to stripping insulation from wires, and removing coatings from fine surfaces.
The main advantages of using lasers in surface cleaning applications include:
• Automated cleaning methods
• Reduce the amount of waste
• Improved security
• No chemicals or sandblasting required
• Non-wear and non-contact cleaning process
Laser cleaning application
Surface polishing and derusting in steel manufacture
Laser cleaning is also an effective and efficient method to remove rust and oxide layer from the surface of metal materials. Rust and oxide layers are contaminants that form on metal surfaces due to natural or artificial processes. When metals are exposed to moisture, they react with water to form ferrous oxide, which causes rust. This rust can degrade the metal and make it unsuitable for use in a variety of applications.
On the other hand, due to the heat treatment process, the metal surface will form an oxide layer, the oxide layer will discolor the metal surface, thus hampering the subsequent finishing operation.
Removal of these unwanted surface deposits requires a descaling treatment to provide a smooth surface for pre-finishing and finishes such as electroplating.
Traditional rust and scale removal methods include physical methods, such as sand blasting, polishing, scraping device, additional purge and wire brush, etc. There are also chemical methods, such as the use of alkaline or acidic chemicals to remove layers of oxide. However, these methods not only cause environmental pollution, but also cause damage to the base metals.
To avoid these shortcomings, laser cleaning has become the preferred method for rust and scale removal operations. The rust layer/oxide layer is removed by irradiating a laser beam with peak power and high repetition frequency on the rust layer.
The laser must be fired in short pulses to avoid damage to the base metal. The rust quickly absorbs the energy of the laser beam, causing the temperature to rise. Once the temperature is high enough, the rust melts and eventually evaporates.
Pulsed fiber lasers are preferred because they provide greater control over power, wavelength, and pulse duration, thereby allowing the rust/oxide layer to evaporate without causing any damage to the substrate material.
The laser cleaning process can also be used for surface cleaning. Before applying a protective coating against corrosion to steel parts, the surface of the parts must be cleaned so that there are no contaminants on the surface.
Surface cleaning/preparation All contaminants need to be removed from the surface of the steel part in preparation for the application of a protective coating. These contaminants include oil, grease, oxide layer, hydrate, shop primers, etc.
Because fiber laser cleaning uses a non-friction, non-contact method and does not involve solvents, chemicals or grinding media, it is ideal for surface cleaning preparation and rusting/descaling. The cleaning process can be done on a small or large scale, and the cleaning process can be automated. Laser cleaning is an environmentally friendly, economical and effective method of rust removal, which can prepare the surface of parts to be coated with protective coating.
Clean the anode assembly
The aluminum smelting industry uses carbon blocks as "sacrifice" anodes in primary aluminum production. The quality of anode has influence on the environment, economy and technology of aluminum production. A small portion of the battery power is used to overcome the resistance of the prebaked anode.
The presence of dirt and other contaminants increases the resistance of the anode, resulting in more battery power consumption. The presence of contaminants also shortens the life of the anode by increasing the consumption rate during smelting. From an efficiency point of view, it is necessary to clean and remove all contaminants from the surface of the anode assembly before it is used in aluminum smelting operations.
In addition, the anode assembly is a valuable tool that can be reused, but its main components must be thoroughly and carefully treated under specific conditions. Laser cleaning can meet the specific conditions that the anode assembly can be reused.
3 Laser cleaning can be used
◎ Remove carbon bottom residue
◎ Clean cathode rod
◎ Remove contaminants from casing and short rod
4. Prepare for metal bonding
In order to improve process stability, surface adhesion and better welding quality, the surface of the metal material to be joined must be prepared before welding and other joining techniques can be applied.
Without the necessary cleaning of the surface of the metallic material, joints and joints are prone to degradation, aggravation of wear and even catastrophic failure. Laser cleaning can be used to treat the surface before bonding, resulting in excellent bonding strength and improved corrosion resistance and durability.
Laser cleaning is suitable for bonding preparation because it removes oxides and other contaminants, such as oils and oxides, that can reduce bonding strength. Laser cleaning is particularly suitable for applications involving curved surfaces, or for cleaning parts with highly complex three-dimensional geometries.
One of the major benefits of laser cleaning is the ability to fine-tune its power and wavelength to allow precise correction of metals used in microstructure, such as magnesium and aluminum. It also gives the material high corrosion resistance, ensuring a stable, durable bond.
In recent years, bonding is increasingly used in structural design applications instead of the traditional bonding techniques such as riveting and welding. This is because the cementing method has many advantages over traditional techniques.
These benefits include uniform stress distribution, reduced corrosion, structural reduction, vibration attenuation and sound insulation. However, these benefits can only be realized if the surfaces to be bonded are carefully cleaned.
Laser cleaning is ideal for such applications because it carefully removes oil, rust, protective coatings and other contaminants created during transportation without causing damage to the base material.
Pretreatment for brazing and soldering
Laser cleaning has also proved effective in welding and brazing pretreatment applications. In shipbuilding, precision tool manufacturing, automotive and other related industries, the surface of aluminum and steel must be treated before it can be welded.
Laser welding preparation is one of the many applications of laser cleaning, which helps to remove ferrous and nonferrous metals, lubricants, and other contaminants from metal and aluminum surfaces in preparation for high-quality welding. It also ensures a smooth and non-porous brazing weld.
When used for welding and brazing pretreatments, laser cleaning performs the following operations:
Thoroughly remove workshop primer, hydrate and oxide layer
◎ Remove grease and grease
In addition to welding and brazing preparation, lasers can also be used to remove welding residues, such as residual flux and oxide materials, as well as thermal stains on finished welded joints.
The benefits of using laser cleaning in welding and brazing pretreatments include:
◎ Wavelength and power can be adjusted, which is used to accurately handle the joint surface in the thickness range of various materials
◎ No damage to the base material (galvanized layer of steel plate)
6. Locally remove coating
Laser cleaning is particularly effective in applications that require partial removal of paint or coatings from surfaces. It can be used on almost all surface types, whether chemically anodized, oxidized or organic. Laser cleaning is used in the automotive and aerospace industries to remove coatings and paints while maintaining the integrity of the base material.
Fiber lasers are the first choice for coating removal applications. They overcome some of the challenges inherent in past topically removed coating applications by precisely removing the coating from a specified area.
Lasers can be used to:
◎ Precise processing of function and design surface
◎ Creating Faraday Cages and Continuous Contactors for the Aerospace Industry
◎ Remove partial paint for EMC
◎ Provide junctions for wire connections
◎ Strip coating in electronics and automotive industry
Laser cleaning is very effective in situations where critical welds on the painted structure/parts must be removed to facilitate inspection. The laser can remove the coating without the need for hand or power tools, abrasives or chemicals that can hide problem areas and cause further damage to the surface.
7 Selective paint removal
Selective paint removal is one of the many applications of laser cleaning. In the automotive and aerospace industries, it is sometimes necessary to remove the top layer of paint while protecting the primer. Typically, top weathering coatings on vehicles need to be completely removed before applying new paint.
Because the physical and chemical properties of the topmost paint are different from those of the primer, the power and frequency of the laser can be set to remove only the topmost paint.
Because the laser has no mechanical, chemical or thermal effect on the primer, the primer remains intact. This ensures the corrosion resistance of the primer. When the parts need to be exposed to metal, metal to metal electrical contact, the best use of laser cleaning process, because it can save time and materials, but also improve the surface quality of the finished product.
The use of lasers for polishing, surface cleaning and coating removal is rapidly expanding. Depending on the application, the pulse frequency, energy, and wavelength of the laser must be precisely selected to clean, polish, and ablate the target material. At the same time, it is necessary to prevent any form of damage to the substrate material.
At present, laser cleaning technology is mainly used to clean small parts. Of course, this technology is also likely to be suitable for cleaning large surfaces and large equipment/structures. With the progress being made in this field, these visions are expected to become a reality in the near future.
Compared with the traditional cleaning methods such as mechanical friction cleaning, chemical corrosion cleaning, liquid-solid strong impact cleaning, high-frequency ultrasonic cleaning, laser cleaning has obvious advantages.
1, is a "green" cleaning method, does not need to use any chemical agents and cleaning fluid, cleaning down the waste is basically solid powder, small volume, easy to store, can be recycled, can easily solve the environmental pollution caused by chemical cleaning;
2. The traditional cleaning method is often contact cleaning, which has a mechanical force on the surface of the cleaning object. The surface of the damaged object or the cleaning medium is attached to the surface of the object to be cleaned, which can not be removed, resulting in secondary pollution.
3, laser can be transmitted through optical fiber, with the cooperation of robot hand and robot, convenient to achieve remote operation, can clean the parts that are not easy to reach by traditional methods, which can ensure the safety of personnel in some dangerous places;
4, laser cleaning can remove various types of pollutants on the surface of various materials, to achieve the cleanliness that conventional cleaning can not achieve. In addition, it can selectively clean the contaminants on the material surface without damaging the material surface.
5, laser cleaning efficiency is high, save time;
6, the purchase of laser cleaning system, although the one-time investment in the early stage is high, but the cleaning system can be used for a long time and stable, and the operation cost is low.
Traditional cleaning industry has a variety of cleaning methods, mostly using chemical agents and mechanical methods for cleaning. In our country environmental protection laws and regulations requirements are more and more strict, people's awareness of environmental protection and safety is increasing today, industrial production cleaning can be used in the chemical species will become less and less. How to find a cleaner, and not damage the way of cleaning is a problem we have to consider. Laser cleaning has no grinding, non-contact, no thermal effect and is suitable for a variety of material objects such as cleaning characteristics, is considered to be the most reliable, the most effective solution. At the same time, laser cleaning can solve the traditional cleaning method can not solve the problem.
The principle of
The process of pulsed Nd:YAG laser cleaning depends on the characteristics of the light pulse produced by the laser, based on the photophysical reaction caused by the interaction between the high intensity beam, the short pulse laser and the pollution layer. Its physical principles can be summarized as follows:
A) The beam emitted by the laser is absorbed by the contaminated layer on the surface to be treated.
B) The absorption of large energy forms a rapidly expanding plasma (highly ionized unstable gas), producing a shock wave.
C) Shock waves break pollutants into fragments and remove them.
D) The optical pulse width must be short enough to avoid heat accumulation that would damage the treated surface.
E) Experiments show that when there is an oxide on the metal surface, the plasma is generated on the metal surface.
Plasmas are produced only if the energy density is above the threshold, which depends on the layer of contamination or oxide being removed. This threshold effect is important for effective cleaning while ensuring the safety of the substrate material. There is a second threshold for the presence of plasma. If the energy density exceeds this threshold, the substrate material will be destroyed. In order to carry out effective cleaning on the premise of ensuring the safety of the substrate material, the laser parameters must be adjusted according to the situation so that the energy density of the light pulse is strictly between the two thresholds.