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Process of vacuum aluminum plating for car lamp Mar 09, 2018

How to ensure the high qualified rate and product quality of the aluminum plating process is still a common problem that plagued the large-scale production at present.

Car headlights of aluminum is usually in high vacuum conditions, the metal Al adhered to plastic surface, the coating thickness is 0.81.2 m, smooth surface, high gloss. In industrial production, vacuum evaporation, surface light injection molding must first coating primer, this is because: first, the adhesion of lamp base material and the aluminum layer, expansion coefficient is more than one order, aluminum film is easily broken, so must choose the suitable primer; second, aluminum substrate surface directly, the aluminum layer generally gloss is very poor, lack of sense of metal, seriously affect the quality and optical properties of light; third, the release of large amounts of gas base resin and various precipitates in vacuum, containing residual moisture, solvent, plasticizer, low residual monomer and polymer material, effects of pumping speed. After spraying the bottom coating, the volatile components can be closed and the pumping rate can be greatly improved.

Heat source existing application based on high temperature generated in the working condition of heat can produce nearly 200 degrees in the narrow space, the heat convection with radiation, heat conduction, long-term high temperature test therefore lamp bezel must withstand 160 DEG C. In such harsh environments and cost considerations, the most widely used materials in the reflection bowl (car light concentrator) are BMC plastics.

After forming BMC automobile lamp surface must be processed, in order to aluminum. Due to the limitation of their capital, equipment and technical strength, the domestic car manufacturers have different aluminum plating processes. They are basically: surface dedusting, cleaning, high temperature drying, priming, low temperature drying, aluminum plating, products drying, low temperature drying, top coat.

Cleaning process is mainly to remove greasy dirt and impurities on the surface of the lamp after molding, can use special detergent soluble water, also use water after washing and drying, high temperature (180 DEG and 200 DEG C, about 1H or so) to remove the surface water and the influence of the aluminum in the free surface release agent. The upper primer is for the better combination of the reflective surface after the aluminum plating and the base of the lamp, so as to prevent the surface off or peeling off of the aluminum surface after being heated. The next process of aluminum plating is basically vacuum process, so that the aluminum and aluminum wire can be evenly adsorbed on the reflector surface of automobile lamp after the electric heating and melting of aluminum wire, and then the above paint protects the surface of aluminum coating. In the whole process, the influence of BMC molding materials on the surface quality of aluminum lamp is quite important. Common aluminum plating defects, such as oil pollution, spots and uneven coating thickness, all have more or less relationship with material selection and molding.