Curing Powder Film

After the powder has been applied to the component it is heated. When heated, the powder film will first melt, flow and bond to the substrate being coated. Continued heating will "cure" the powder - curing involves a chemical reaction called "cross linking" and the resultant "cured" coating will not, like the original powder, melt or dissolve in solvents - it forms the protective coating we seek.

Most powders cure at around 180C and must be at this temperature for around 10 to 12 minutes and this time does not include the heating up or cooling down of the component but is the dwell time: the length of time that the component must be held at the appropriate temperature for curing to take place.

The dwell time and oven temperature will vary according to the size of component, atmospheric conditions and the manufacturer's recommendations for that particular product.

The most frequently used methods of heating aluminum profile powder coatings are convection and radiation, both involve the component being passed into or through the heated area of an oven in order to melt and cure the powder film. The ovens will usually have an extractor to purge the chamber of the small amount of waste gases produced during the curing process.

Convection curing

This type of curing is by far the most popular method used in the curing of powder coatings. The component will be thoroughly heated to the required temperature where curing will take place. This type of oven usually consists of a large insulated box into which the parts will be placed for curing, or a tunnel through which the parts travel, via heat seals, into the main chamber of the oven.