Making a choice for the best heat source for curing ovens
Powder coat does not care about heat source during curing. Gas fired ovens can be used as well as curing ovens that work through electricity. The choice however, is largely influenced by cost because a curing oven consumes a lot of energy. Gas fired ovens and electric ovens use the same amount of energy units but electricity has a much higher price than gas making electric ovens much more expensive to run. However, it is should also be considered that while Gas fired ovens are cheaper to operate they cost more than electric ovens in terms of upfront costs. In addition, if the choice is Gas fired ovens, there must be access to gas lines otherwise electricity will be a more convenient and cheaper option because it does away with the additional expense of installing gas piping into the facility. Oven design is also critical to ensure that there is efficient use of energy with temperature exactly controlled according to the specified curing temperature.
Selecting a heating method for powder curing
The most obvious choices for curing powder coating are either the convection oven or infrared oven. Convection ovens offer more flexibility and lower risks of overheating but at the expense of size, speed and energy efficiency. Infrared ovens are capable of delivering higher production rates with low energy consumption. However, infrared ovens require close control to ensure that the product is not overheated. To make a compromise between the two, another option is introduced in the form of combination ovens.
In the combination oven, the infrared section of the curing oven produces a rapid rise in the temperature of the workpiece and as the source of heat increases, so thus the proportion of heat transferred through radiation. If the workpiece is thin like metal sheet, it can be assumed that heat will be within a few degrees of coating temperature but if the workpiece is thick and has a complex shape, uniform temperature is very unlikely. A part that has a complex shape won’t easily reach curing temperature because its entire mass will not be exposed to radiation. Radiation travels in straight lines so that the part of the workpiece which is not in its line of sight will not receive direct radiation particularly those that are hidden in the shadows.
According to most powder coating experts, curing time relates to substrate temperature which suggests that the entire workpiece must be heated; however, adhesion is only affected by the temperature of the substrate which is in direct contact with the coating. Convection that works through heated air will provide the required temperature on the workpiece.