Curing with an Infrared Oven

Q. We are in the process of planning a new powder coating system and we have a question about oven options. Our old system uses a convection oven for curing, but we have heard that an infrared oven can save time and fit into a smaller space. We want to know if it is a good way to cure powder. Can we cure powder with an infrared oven?

A. Yes, you can cure with infrared. Infrared (IR) emitters cure by exposing the coating to electromagnetic energy. The thermal energy needed for cure is provided by exposing the part surface to the IR emitter for a period of time at a certain distance. The part surface and the powder absorb energy from the emitter and cure much faster than convection ovens. This type of curing does not rely on heating the surrounding air and it is not necessary to heat the entire core of the part. The oven size is smaller and usually requires less exhaust. In addition to being faster, the IR curing oven can also help limit exposure to particulates that can be found moving in the convection oven environment and also provide good flow of the powder coating.

In some cases, an IR oven can be used without any convection oven addition. Very large or heavy parts can be cured faster without the need to heat the entire core of the part. Since the IR energy is a form of electromagnetic energy, the line of sight between the emitter and the part surface is important. Areas that are not directly exposed to the emitter will take longer to heat up and therefore longer to cure. The absorption rate can be very different if the part has a lot of mass and does not expose much surface to the emitter. If the part being cured has a complex shape it will be harder to cure it using the IR oven alone.

In addition, infrared energy is more sensitive to time than a convection oven because of the intensity. If you expose a surface too long, it may overheat; if you do not expose it long enough, it will not cure. For that reason, it is often advisable to have some convection time as well as the IR time. The IR oven will jumpstart the process and help shorten overall cure time, while the convection oven will help to even out the thermal levels in various areas of the part.