Laser cleaning, as a new "green" technology poised to replace traditional cleaning methods, offers a pollution-free and consumable-free industrial cleaning process. With its micron-level precision and the ability to integrate into unmanned automation systems, it has been widely applied in the production of various automotive components such as power battery systems, transmission bearings, axles, wheels, and tires.
Principles of Laser Cleaning
The principle of laser cleaning can be broadly divided into three types: thermal effect, photoablation, and vibration. Different types of lasers produce various laser beams that utilize the difference in the absorption coefficient of the base material and surface contaminants at a certain wavelength. This causes the base material and surface contaminants to absorb energy, leading to thermal expansion and detachment. The instantaneous high temperature causes the dirt to evaporate, gasify, or decompose, while ultrasonic waves generated on the solid surface create mechanical resonance that breaks up the dirt layer or condensates.
Compared to traditional industrial cleaning methods like sandblasting or shot blasting, laser cleaning's most significant feature is its non-abrasive and non-contact nature. It has no thermal effect, does not exert mechanical force on the object being cleaned, does not damage the object's surface, does not destroy the base, and does not produce secondary pollution, making it an environmentally friendly and consumable-free cleaning method.
Laser Cleaning Equipment for the Friction Industry
After prolonged use, automotive components inevitably accumulate dust, rust, and oil stains. If these parts become too dirty, it can lead to poor filtration and cleaning efficiency, allowing more impurities to enter the oil circuit and cylinder, exacerbating wear on the components and increasing the likelihood of malfunctions. For the safe operation of vehicles, important components such as wheel hubs, brake pads, brake discs, and engine covers need regular inspection and maintenance. Ensuring the cleanliness of various workpieces and components is an essential part of the maintenance process.
In the production process of brake pads, after flattening and before spray painting, the pads need to be cleaned. This step is typical due to its large output and broad scope. Here, we compare the advantages and disadvantages of steel brush, sandblasting, and laser cleaning for this application:
- Cleaning Efficiency: Steel brush equipment cannot completely clean the residual adhesive on the surface after flattening, resulting in poor spray painting outcomes. Both sandblasting and laser cleaning can thoroughly clean the surface residues, with sandblasting being faster. However, considering the entire production line's time, including pre-flattening oven entry and post-spray painting curing, sandblasting's speed is somewhat redundant. Although slower, laser cleaning can still match the production line's pace.
- Energy Consumption: Steel brush machines consume about 8KW/H, ranking second among the three. Sandblasting has the highest energy consumption, reaching up to 70KW/H. This is because, although the sandblasting machine itself consumes about 15KW/H for sandblasting, walking, and swinging, the air compressor's hourly energy consumption is as high as 55KW, making it a significant energy consumer. Our laser cleaning equipment has a total energy consumption of only 7KW/H, which is one-tenth of the sandblasting equipment, making it the least energy-consuming of the three.
- Economic and Environmental Impact: Economically, sandblasting equipment consumes 5KG of quartz sand per hour as consumables. The longer the usage time, the more consumables are needed. With increasing national environmental protection requirements, some local governments have classified sand washing machines as non-compliant with environmental standards. Both steel brush equipment and laser cleaning only require electricity, and laser cleaning can save 1-2 laborers due to its automated operation. From an environmental and low-carbon perspective, laser cleaning, with no consumables, emissions, low energy consumption, and no noise, is the most environmentally friendly and low-carbon compliant equipment among the three.
Laser Cleaning Equipment for the Sealing Industry
Laser cleaning applications in the sealing industry mainly include removing oil stains from the surface of stainless steel strips during the production of metal gaskets, cleaning oil stains and residual adhesives from the surface of sealing ring molds, and surface modification of special sealing materials. There are many types of sealing components, typically including O-rings or skeleton oil seals, and sealing gaskets. Laser irradiation instantly evaporates oil stains from the gasket, stripping them from the metal and achieving a clean effect.
Before entering the winding machine, metal spiral wound gaskets need to have the oil film on the surface of the stainless steel coil cleaned. The existing process generally involves chemical soaking for surface treatment. Laser cleaning can meet manufacturers' cleaning requirements for this process. The main challenges in application are adapting to the width of the strip and the speed of the production line. Generally, laser cleaning equipment has a width of 150-200mm, while stainless steel strips range from 1100-1500mm in width; and the cleaning production pace is too fast, generally above 10M/min, which is about ten times higher than the speed suitable for laser cleaning. Our company has developed ultra-wide laser cleaning equipment that can solve the cleaning width adaptation issue. Although the production line speed can be addressed in the process application, the current industry solutions are too costly and require further optimization.
Non-metallic material gaskets are another major category in the sealing industry. These products have a strong absorption rate for fiber lasers in the 1064-1080nm band, which normally causes damage and is not suitable for process applications (e.g., pulsed laser action on rubber material surfaces can cause about 10μm of damage). However, for a few special materials, it can be used as a modification method. For example, rubber materials coated with polymethylhydrogensiloxane can increase the surface friction coefficient to 35mN/m and surface tension to over 38dyne/cm while removing the coating.
At the same time, laser cleaning performs well in processes such as oxide layer cleaning and dot roughening on ceramic and composite material sealing components and has satisfactory results in removing sealant from metal surfaces. It is evident that laser cleaning's performance on different material products varies due to different laser absorption rates, making it a complementary process for surface modification of a few special sealing materials.
Conclusion
Laser cleaning technology stands out as a highly efficient, eco-friendly, and cost-effective solution for industrial cleaning. Its precision and adaptability to automation make it a superior alternative to traditional methods, offering significant advantages in terms of efficiency, energy consumption, and environmental impact. As industries continue to seek sustainable and innovative cleaning solutions, laser cleaning is set to play a pivotal role in shaping the future of industrial maintenance and production.
