Vacuum metalizing is the bonding of metal on a non-metallic surface through a process called physical vapor deposition. The most common metal used in this process is aluminum because of cost, thermodynamic, and reflective properties.
This process works by placing aluminum or other metallic coating material into a vacuum chamber along with the plastic parts that needs to be coated. The aluminum is then heated until it starts to evaporate. The vaporized aluminum condenses on the plastic part as a thin metallic film.
The evaporation takes place by feeding the aluminum onto a heat source. The air in the vacuum chamber is expelled to create a vacuum that is suitable for evaporating the material. Upon contact with objects placed in the chamber, the vaporized metal condenses and creates a uniform layer of vacuum deposited aluminum.
This process is applicable to both solid objects and films. On solid plastic objects, parts are hung on a rotating carousel before it is inserted into the vacuum chamber. During the metalizing process, the parts rotate on the carousel to ensure a uniform coating on its surface.
On films, a roll of untreated plastic film is mounted on one roller while the other end is mounted on an empty roller. Inside the chamber the roll of untreated film will unwind while the empty roller wind-up. As both rollers turn, the vaporized metal will condense on the film that is stretched between the 2 rollers.
Vacuum Metalizing is often carried out to enhance the properties and increase the functionality of an otherwise normal plastic part. Such enhancements includes:
The metalized parts can have a highly reflective chrome finish. This gives the impression that the product is made of metal, and has a highly polished mirror-like finish. Such products often look expensive. Film sheets that has been vacuum metalized can also be coated to give different metallic colors. These are known as colored foils. The use of vacuum metalizing for aesthetics purposes includes:
- Labels and stickers
- Decorative packaging (cosmetics containers, perfume bottles, etc.)
- Christmas decorations
- Bathroom Hardwares
- Automotive interior components and exterior trims
- Car headlamp reflectors
- Trophy and medals
- Casings and buttons on mobile phones and other electrical items
Vacuum metalized surfaces are ideal for insulation because of it’s increased reflectance and radiance properties. Such thermal insulation products has a huge range of application ranging from emergency first aid foil blankets to the construction of space crafts. Other common application include building construction, thermal suits for firefighters, cooking, etc.
Another function derived from the metalization process is to increased barrier properties. Metalized plastic films has great moisture and air barrier. These films are widely used as food and beverage packaging. Another important feature of the vacuum metalizing process is to reduce light transmission, making it an effective light barrier. Light transmission is controlled by the amount of deposited aluminum on the product.
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