The temperature of the powder curing oven varies depending on different types of powder coatings and the materials of the workpieces. Generally speaking, the common temperature of the powder curing oven is around 145 - 200 °C, which can make the workpieces completely cured. The following is a detailed analysis:
A method for curing the base powder of the coating of aluminum alloy wheels is provided. In this method, the base powder is a polyester-epoxy mixed base powder. First, the temperature of the workpiece coated with the base powder is raised to 145 - 152 °C and held for 4 - 6 minutes. Then, the temperature of the workpiece is lowered to 20 - 25 °C by air cooling and held for 12 - 20 minutes. Finally, the temperature of the workpiece is raised to 162 - 170 °C and held for 5 - 7 minutes under ultrasonic waves.
It is mentioned that conventional thermosetting powder coatings require temperatures in the range of 160 to 200 °C and about 10 to 15 minutes, or higher. Low-temperature curing can be defined as 160 °C and below, sometimes with a shorter residence time.
Powder coating is commonly used for the base coating of aluminum alloy wheels for automobiles. The baking temperature of most powders is 180 °C, which is higher than the heat treatment aging temperature of aluminum wheels, which is 155 °C. And the low-temperature curing powder can reduce the baking temperature to about 150 °C.
It is pointed out that the fact that the workpiece needs to be at a temperature between 170 and 200 degrees for up to half an hour has a negative impact on the total coating cost.
When using gas catalytic combustion infrared curing for polyester + TGIC powder coatings, the maximum infrared curing temperature of the coating is 230 °C, which is higher than the maximum hot air curing temperature (200 °C).
The temperature of the powder curing oven is not fixed but is affected by various factors.
Types of powder coatings: Different powder coatings have different compositions, and their curing temperatures will also vary. For example, the curing temperature of polyester-epoxy mixed base powder may be different from that of pure polyester powder coatings.
Materials of workpieces: Workpieces made of different materials have different temperature tolerance. For example, the curing temperature of aluminum alloy wheels may be different from that of other metal workpieces because the heat treatment aging temperature of aluminum alloy will affect the temperature selection during the powder curing process.
Curing methods: Different curing methods also affect the curing temperature. For example, the required curing temperatures may be different when using hot air curing, infrared curing, catalytic curing, etc. Like the gas catalytic combustion infrared curing mentioned in Literature 5, its curing temperature is different from that of hot air curing.
The curing effects of powder coatings will also vary at different temperatures.
Curing effects at higher temperatures: At higher temperatures, the curing speed of powder coatings usually accelerates, but it may also cause some problems. For example, for some thin plate workpieces, there may be an over-drying situation. For thick plate workpieces, there may be a problem that the interior is not completely cured. At the same time, higher temperatures may affect the performance of the workpieces, such as reducing the toughness of the workpieces.
Curing effects at lower temperatures: Curing at lower temperatures can reduce the impact on the performance of the workpieces. For example, for aluminum alloy wheels, the low-temperature curing powder can reduce the baking temperature to about 150 °C, which is beneficial to reducing the impact of high temperature on the elongation and brittleness of aluminum wheels and also realizes energy conservation and reduction of carbon dioxide emissions. However, curing at lower temperatures may require a longer time to ensure the complete curing of the workpieces.
In conclusion, the normal operating temperature of the powder curing oven varies due to various factors, but generally, around 145 - 200 °C can make the workpieces completely cured. In practical applications, it is necessary to select the appropriate curing temperature according to factors such as the type of powder coating, the material of the workpiece, and the curing method to ensure the curing effect and performance of the workpiece.
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