Currently, the coating technology used for plastic components in lamps is mainly achieved through evaporation plating and magnetron sputtering. However, evaporation plating remains the most commonly used method due to its cost-effectiveness and efficiency. With the improvement of living standards, the widespread use of automobiles, and the continuous advancement in auto parts manufacturing, the demand for high-quality coatings on lamp components has also increased.
In particular, the coating of plastic parts for lamps is typically done using vacuum evaporation techniques. Most of these parts only require a thin layer of aluminum film, which is both economical and effective. Aluminum has a relatively low melting point, while the plastics used in lamps have a higher melting point, making it safe to apply aluminum coatings without damaging the base material. Additionally, the equipment required for vacuum evaporation is less expensive compared to other methods, and the resulting aluminized film is of high quality and durable.
Dongguan Huicheng Vacuum Technology Co., Ltd. has developed specialized vacuum coating machines tailored for lamp components, based on the principle of evaporation plating. Before the coating process begins, the incoming plastic parts must be thoroughly dried. This is because the plastic itself may contain moisture, and drying can take anywhere from three to five hours at a controlled temperature of 50 to 60°C. Excessive heat can cause deformation of the plastic, even if it doesn't melt.
During the injection molding process, care is taken to avoid oil contamination, as any oil present can interfere with the adhesion of the coating. If there is significant oil residue, cleaning and degreasing are performed before the parts are cleaned with a soft cloth. After that, any dust is removed using a vacuum cleaner. Since most plastics have a rough surface, a primer is applied first, followed by baking at 60–70°C for 1.5 to 2.5 hours.
The vacuum pump is then used to create a pressure of 1–2×10â»Â² Pa. The aluminum metal is heated using a tungsten wire, evaporating into a fine vapor that deposits onto the surface of the plastic part. Once cooled, the aluminum film is baked to ensure proper adhesion. To prevent oxidation or chemical reactions between the aluminum film and the air, a protective lacquer is applied and cured, completing the coating process.
Without this coating, the light reflection of a plastic lamp would be very poor. However, after the aluminum film is applied, the lamp becomes much more efficient in reflecting light, significantly improving its performance and appearance.
For more information about Huicheng’s vacuum coating equipment, visit: http://news.chinawj.com.cn
Submitted on July 16, 2013.
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