Infrared Basics

Quartz halogen lamps are effective in many industrial heating applications including preheating, curing and annealing of plastic extruded materials. Quartz halogen lamps with focusing reflectors were originally developed for applications in the United States Space Program. These applications often required rapid heating rates, precise control, and the ability to turn the heat on and off instantly. The same benefits also apply in plastics processing, as noted below:

Quartz halogen lamps are similar to the incandescent lamps used in everyday lighting applications. The similarities include the ability to instantly turn on and off, and the ability to focus the energy. The differences are that a quartz envelope is used (instead of glass) and the filament if larger, which improves lamp life and increases the emitting area. The quartz halogen lamp (see Figure 1) consists of a helically wound tungsten filament encased in a quartz envelope. Tungsten is a fast responding resistive elements that is capable of surviving temperatures in excess of 2750 °C. The quartz envelope allows transmission of IR energy, while protecting the filament from convective cooling and corrosion. The quartz is evacuated and filled with inert gases. A small amount of halogen gas is added to promote long life of the emitter. Rated life for most T3 lamps is 5000 hours. Actual life will depend upon the application and environment and may be greater of less than rated.