A Uniform Cure: Achieving temperature uniformity in a powder coating oven requires the proper airflow design.

Published Date: 
Thursday, September 3, 2009

Veterans of the finishing industry agree that temperature uniformity and proper airflow design have a large impact on obtaining consistent, top-quality curing results for powder coatings. But while these characteristics are closely related, it is important for buyers to evaluate them separately. You can buy an oven with excellent empty oven chamber temperature uniformity and still not obtain acceptable results if the airflow is not designed for the way you load your parts inside the oven.

Oven temperature uniformity is defined as the overall temperature variation from a given setpoint. Acceptable uniformity tolerances are stated as a deviation - for example, ±10°F, which means that the temperature of all points that are measured within the work chamber need to be within a 20°F band around a specific setpoint. Temperature tolerances within the work chamber seem to become more stringent each year. Back in the days when most finishing was liquid-based, uniformity was rarely an issue.

The vast majority of liquid-based coatings 15 years ago would tolerate temperature variances of ±15 to 25°F. It seemed like any old box with some heat would provide a satisfactory cure. Today’s powder-based coatings, as well as some of the specialty liquid paints, require a much tighter tolerance. Most powder coatings require a tolerance of ±10°F from setpoint to obtain ideal curing conditions.