Powder Coating Gun Troubleshooting Guide
Are you having trouble solving problems when using a powder coating gun? Are you confused by problems such as clogging of the nozzle of the powder spray gun, clogging of the powder conveying channel, poor powder adsorption capacity, and poor powder coating curing effect? Study this guide carefully so that you have more experience and methods to troubleshoot problems encountered during the powder coating process, and have practical solutions to various powder spray gun failures.
1. Uneven powder coating
- Uneven atomization of the spray gun: Uneven atomization of the spray gun will lead to uneven sizes of powder particles, resulting in uneven coating thickness. The main reasons for uneven atomization are: uneven nozzle aperture, nozzle wear, nozzle blockage, air pressure that is too high or too low, powder flow rate that is too large or too small, etc.
- The distance between the spray gun and the workpiece is inappropriate: If the spray gun is too close to the workpiece, the powder particles will adhere to the surface of the workpiece and form plaques; if the spray gun is too far away from the workpiece, the powder particles will fly in the air, resulting in a thin coating. Uneven.
- The moving speed of the spray gun is inappropriate: If the spray gun moves too fast, the powder particles cannot be fully leveled and ripples are formed; if the spray gun moves too slowly, the powder particles accumulate and form plaques.
Solutions
- Regularly check the atomization effect of the spray gun, and repair or replace the nozzle promptly if any problems are found.
- According to the shape and size of the workpiece, adjust the distance between the spray gun and the workpiece.
- Control the moving speed of the spray gun to keep it uniform.
2. Powder particles vary in size
- Powder particle aggregation: If the powder is not dispersed sufficiently before spraying, it can result in inconsistent particle sizes.
- Poor powder storage conditions: Improper powder storage conditions can cause the particles to clump or absorb moisture, which can affect particle size.
- Air pressure issues: Unstable air pressure may cause changes in powder particle size.
Solution
- After the powder coating is put into the hopper, a corresponding vibrating screen or other corresponding equipment needs to be equipped to disperse the powder coating as evenly as possible.
- Strictly control the storage environment of powder coatings, control the humidity and temperature of the air, and avoid caking.
- Check whether the air compressor is working properly or whether the compressed air pipeline is damaged or leaking, etc., and ensure that the air pressure delivered to the powder spray gun is constant.
3. Powder coating gun nozzle clogged
- Powder particle scaling: Powder particles will collide and rub during the spraying process, generating heat, causing some powder particles to scale in the nozzle.
- Moisture of raw materials: Excessive humidity in the storage environment of powder coatings will cause the raw materials to clump and block the nozzle of the powder coating gun when passing through it.
- Powder coating contains impurities: Powder coating contains impurities, which can also cause nozzles to clog.
Solution
- Clean the nozzle regularly: After each spraying job, the nozzle of the powder spray gun should be cleaned to remove powder particles in the structure inside the nozzle
- Install a filter between the powder tank and the powder spray gun, which can effectively reduce impurities in the raw materials from clogging the nozzle
- Strictly control the storage humidity and temperature of powder coatings to avoid caking
4. Poor adsorption of powder coating
- Poor surface treatment of the workpiece to be sprayed: oil stains, modifications, oxidation, dents and cracks on the surface of the workpiece will directly affect the adsorption force of the powder coating.
Solution
- The sandblasting process can effectively remove oil stains and impurities on the surface of the workpiece to be sprayed. Chemical treatment of the workpiece surface can also improve the adsorption rate of powder spraying.
- Adjusting the voltage and air pressure of the powder spray gun according to different powder coating raw material ratios can effectively improve the adhesion of the powder coating on the workpiece surface.
The above are some common problems during the spraying process of powder coatings, which can be effectively solved by following the above failure analysis and solutions. Regular inspection and maintenance of powder spray guns can effectively avoid the above problems and greatly improve the normal service life of powder spray guns. In addition, the construction environment of the spray workshop, regular inspection and maintenance of electrical equipment, and professional skill training of operators can also reduce the probability of powder spraying failures.
Erik
Doctor of Chemical Engineering, expert in the field of powder coatings, with over 20 years of professional experience in the research and application of powder coatings
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