Issue link: https://www.e-digitaleditions.com/i/1051901
I n the 1990's, a primary sales pitch for the use of infrared (IR) by equipment manufacturers was the promotion of the technology as a booster, or gelling oven. is applica- tion would boost the part temperature with IR (thus causing the powder to flow or gel) prior to the part entering in a con- vection oven used for curing the powder. Generally, this solution would be implemented to allow customers to in- crease throughput while reducing the amount of floor space required when compared with adding more convection ovens. It didn't take long before we began to see IR move from outside the oven into the vestibule of the oven to save even more floor space. In the past few years, we're starting to see great success with IR being installed inside the convection heat zone, especially with regard to convection batch ovens. is application not only eliminates any need for additional floor space, but also takes advantage of the added energy (BTUs) coming off the IR heaters to the overall heat balance of the convection. ere are two major advantages for this type of application: 1. Heat large geometrically complex parts that provide a reduction in both cycle time and energy 2. Batch small and large parts together without under- or over-curing any of the parts inside the convection oven In this article, we'll examine two applications that compare the use of a straight convection oven with the use of a com- bination IR-convection batch oven where the IR is placed inside the oven. First application: Large geometrical parts Several industrial customers use pure convection to preheat and cure heavy parts of various shapes. In many instances, their large convection ovens (usually gas-fired) must be turned on a couple of hours prior to operation to allow the oven to completely heat up before production can begin. Once the oven is at temperature (usually 400°F to 500°F), the part is then placed in the oven to soak. Generally, the parts are left in the oven for 1 to 2 hours to make sure the part has reached temperature. Marek W. Urban, Ph.D. Clemson University IR Curing ShopTalk Infrared Equipment Division of IHEA This column is provided to you by members of the Infrared Equipment Division (IRED) of the Industrial Heating Equipment Association (IHEA). The group includes infrared (IR) curing equipment suppliers from throughout North America. We publish the column several times a year to give you the latest informa- tion about IR curing techniques and equipment. Contact information is at the end of the column. Most IR manufacturers offer testing for free or for a fee. Any IRED member can assist you in finding solutions to curing problems and best practices for finishing of coatings. This issue's column was submitted by IRED members Scott Bishop and Joel Watts, Alabama Power Co., Birmingham, Ala. Maximize your convection oven by using infrared Figure 1 Electric convection batch oven 300kW Figure 2 Electric convection batch oven 300kW with IR installed 14 POWDER COATING, November 2018