The pretreatment process is divided into manual pretreatment and automatic pretreatment, and automatic pretreatment is divided into automatic spraying and automatic immersion spraying. The workpiece must be degreased and de-rusted before powder coating. There are many chemicals used in this section, such as rust remover, degreasing agent, surface conditioner, phosphating agent, etc.
In the powder coating line pretreatment section or workshop, firstly, attention should be paid to establishing the necessary strong acid and alkali procurement, transportation, storage, and use systems, providing workers with the necessary protective clothing, safe and reliable dressings, handling and equipment configurations; developing accident emergency handling measures and rescue measures. Secondly, powder coating line pretreatment part of the existence of a certain amount of waste gas, waste liquid, and other three waste, so in the environmental protection measures, must be configured waste gas, drainage liquid, and three waste treatment devices.
The quality of the pre-treated workpieces varies with the pre-treatment solution and the process flow of the powder coating line. To prevent the workpiece from rusting again within a short period, well-treated workpieces should be phosphate or passivated several times before and after treatment. Before powder coating, the phosphate workpiece should also be dried to remove surface moisture. Small batch single-piece production, generally using natural air-drying, sun-drying, air-drying. Large-scale assembly operations generally use low-temperature drying, using ovens or drying channels.