Baking of Prepainted Steel
When the steel is exposed to high temperatures, sometimes in preparing for painting, the steel must be heat-treated for proper adhesion and forming ability. Prepainted steel is sometimes baked after it is formed to increase the life of the coating, improve the appearance of the product for the customer, and improve durability in both indoor and outdoor conditions.
The process of baking steel is known as “baking of prepainted steel”. This form of heat treatment is done to increase the chemical bonding of the paint to the steel, to reduce flaking and peeling, to increase the moisture resistance of the coating and to improve the mechanical properties. The baking process is done in a controlled environment, using specific temperatures and duration times.
For baking of prepainted steel to be successful, the temperature and duration of heating must be carefully monitored. The temperature of the oven depends on the type of paint that is being applied, but it generally ranges from 300°F to 800°F (149°C to 427°C). The duration of the baking process also depends on the type of paint that is being used, as well as the desired outcome. This can range from 30 minutes up to several hours.
When baking of prepainted steel, it is important to understand the four primary effects that the baking can have on the coating. These effects are adhesion of the paint to the metal deformation, hardening of the paint film, improved corrosion resistance and hydrophobicity. The first three of these effects are positive and important for the final product, while the fourth effect is more of a consideration in terms of design and function.
Adhesion of the paint to the metal greatly depends on the temperature and duration of the baking process. Generally, the higher the temperature and longer the duration of the baking, the better the adhesion of the paint. Hardening of the paint film occurs when the temperature is increased to any degree, while the full hardening effect is only achieved when the temperature is raised above a certain threshold, and this varies depending on the paint that is being used. The improved corrosion resistance and hydrophobicity of the coating also depend on the baking temperature and duration.
To ensure successful baking of prepainted steel, it is important to work with experienced personnel who understand the properties of the particular steel and painting requirements. The batch size should also be considered, as larger batches may require longer baking times. Proper oven settings should be calibrated for the desired outcome and all safety protocols should be followed. Finally, it is important to inspect the finished product for any defects that may have originated from the baking process.
