Spray molding process for stainless steel insulated cups

Spray molding is a surface treatment method that sprays plastic powder onto parts. Spray coating, also known as electrostatic powder coating, is a commonly used decorative technology for metal surface treatment internationally since the 1980s. Compared with ordinary spray painting surface treatment, this technology has advantages in advanced technology, energy efficiency, safety and reliability, and bright color. Therefore, it is often applied in the fields of light industry and home decoration. Its working principle is to charge plastic powder through high-voltage electrostatic equipment, and under the action of an electric field, spray the coating onto the surface of the workpiece. The powder will be evenly adsorbed on the surface of the workpiece, forming a powdery coating; After high-temperature baking, the powder coating flows and solidifies, and the plastic particles will melt into a dense final protective coating with different effects; Firmly adhere to the surface of the workpiece.

 

Charge the plastic powder through a high-voltage electrostatic device, and under the action of an electric field, spray the coating onto the surface of the workpiece. The powder will be evenly adsorbed on the surface of the workpiece, forming a powdery coating; After high-temperature baking, the powder coating flows and solidifies, and the plastic particles will melt into a dense final protective coating with different effects; Firmly attached to the surface of the workpiece,spray molded products are mostly used for indoor boxes, and the paint film presents a flat or matte effect. Spray powder mainly includes acrylic powder, polyester powder, etc.
advantage
No need for diluents, construction is pollution-free to the environment and non-toxic to human health; The coating has excellent appearance quality, strong adhesion and mechanical strength; Short curing time for spray painting construction; The corrosion resistance and wear resistance of the coating are much higher; No primer required; Easy construction with low technical requirements for workers; The cost is lower than the painting process; Some construction scenarios have explicitly stated that the use of electrostatic spraying technology is necessary for treatment; During the electrostatic powder spraying process, there will be no common flowing phenomenon in the painting process.
Process principle
It utilizes the phenomenon of corona discharge to cause the powder coating to adsorb onto the workpiece. The process is as follows: the powder coating is fed into the spray gun by the powder supply system through compressed air gas, and a high-voltage electrostatic generator is added at the front end of the spray gun to generate high voltage. Due to corona discharge, dense charges are generated nearby. When the powder is sprayed out from the gun nozzle, charged coating particles are formed, which are attracted to the workpiece with opposite polarity by electrostatic force. As the amount of powder sprayed increases, the accumulation of charges also increases. When a certain thickness is reached, due to the electrostatic repulsion effect, adsorption is not continued, and the entire workpiece obtains a certain thickness of powder coating. Then, the powder is heated to melt, level, and solidify, forming a hard coating film on the surface of the workpiece.
process flow
1. Pre processing:
Purpose: To remove oil, dust, and rust from the surface of the workpiece, and generate a "phosphating layer" on the surface of the workpiece that is corrosion-resistant and can increase the adhesion of the spray coating.
Main process steps: oil removal, rust removal, phosphating, and passivation. After pre-treatment, the workpiece not only has no oil, rust, or dust on the surface, but also generates a uniform and rough gray phosphating film on the original silver white glossy surface that is not easy to rust, which can prevent rust and increase the adhesion of the spray coating.
2. Electrostatic spraying
Purpose: To evenly spray powder coating onto the surface of the workpiece. Special workpieces (including areas prone to electrostatic shielding) should be sprayed using high-performance electrostatic spray molding machines.
Process steps:
Using the principle of electrostatic adsorption, evenly spray a layer of powder coating on the surface of the workpiece;
The fallen powder is recovered through a recycling system and can be reused after sieving.
3. High temperature curing
Purpose: To heat the powder coating on the surface of the workpiece to the specified temperature and keep it warm for the corresponding time, so as to melt, level, and cure it, thereby obtaining the desired surface effect of the workpiece.
Process steps: Push the sprayed workpiece into the curing furnace, heat it to the predetermined temperature (usually 185 degrees), and keep it warm for the corresponding time (15 minutes); Open the furnace and take it out for cooling to obtain the finished product. Generally, the heating temperature and holding time vary depending on the workpiece.
Tip: Heating and control system (including various heating methods such as electric heating, fuel oil, gas, coal, etc.)+insulation box=curing furnace.
4. Furnace cooling
Cooling out of the furnace is a process of cooling the results of the spray molding process back to normal temperature.
5. Decorative treatment
Purpose: To achieve a special appearance effect of the workpiece after electrostatic spraying, such as various wood patterns, patterns, and gloss enhancement.
Process steps: Masking; Transfer printing and other processing techniques.