Vacuum Metallising with aluminium is the most efficient and cost effective way to achieve high levels of reflectivity in most cases of lighting. Lighting Reflectors can be categorised as automotive, beacons, hazard, mining, light bars, search lamps, safety, commercial, domestic, head lamps and rear light clusters.
Usually reflectors are processed using base and top lacquers, with stoveing and vacuum metallising between layers of lacquer. Over recent years plasma has become the automotive industries choice, as opposed to using the somewhat dated aforementioned lacquer systems.
Dual can offer both Traditional Lacquering and state of art Plasma Systems. Traditional Lacquering System using High Vacuum Metallising Reflectors are loaded onto an apt jig. The lacquers used will depend on the substrate they adhere to and the temperatures the reflectors will need to endure whilst in service. A typical high temperature reflector will be found in automotive headlamps which need to withstand heats of up to 150 degrees Celsius.
The reflectors will be stoved at the pre-destined temperature for a designated time, usually one hour.
The next stage will be to vacuum metallise the parts using high purity aluminium at a vacuum reading of 5 x 10-8 millibar. The aluminium will be evaporated (melted) using tungsten filaments which are charged with high voltage power and simultaneously the parts are rotated in a planetary fashion. Consequently allowing the aluminium to evaporate onto the surface of the parts in a “line of sight” method.
Now due to the stoved base lacquer having a high gloss level of finish, the aluminium reflects this and becomes a reflector. A top lacquer is now applied to protect the aluminium from corrosion and oxidation. This is sprayed either manually or automatically.
The parts are then stoved at a lower level of temperature than the base lacquer to avoid any movement of the aforementioned base lacquer. The reflectors are tested for adhesion by “cross hatch” and filament tape.
High Vacuum Metallising in Plasma
Instead of using traditional base and top lacquers, Dual offer plasma treatment. Provided the reflector mouldings are of high quality they can be easily processed to the standards of the automotive industry and other demanding industries.
After the reflectors are fitted onto dedicated jigs, the jigs will be loaded into the twin doors of the plasma machine. The parts are prepared using plasma which cleans and keys the surfaces in medium vacuum ready for metallising. This is by the traditional vacuum metallising process as described earlier.
The second plasma process involves silicone fluid injected into the vacuum chamber when introduced to the plasma. This creates a protective silicone coating to adhere to the metallised surface which will protect the reflectors from oxidation.
The parts are tested for adhesion by the aforementioned “cross hatch” test and placed into a diluted mix of sodium hydroxide and water for 15 minutes.
It must be stressed that reflectors treated with plasma are only ideal when protected by a sealed lens.
Visit our gallery to view the Lighting Reflectors range.