With the continuous improvement of industrial automation, automatic spray guns, as the core equipment in painting operations, have been widely used in automobile manufacturing, furniture production, hardware processing and other fields. Its precise spraying effect and efficient operation capabilities have become the key to improving product quality and production efficiency. However, many companies have insufficient mastery of the use specifications and adjustment skills of automatic spray guns, resulting in uneven spraying quality. Recently, experts in the coating industry have given detailed interpretations of the correct use and adjustment methods of automatic spray guns to provide professional guidance for industry practitioners.

Preparation before use: Build a solid foundation for safety and equipment

"The standardized use of automatic spray guns begins with perfect preliminary preparations, which are not only related to the spraying effect, but also directly affect the safety of operation." Zhang Limin, an industry expert who has been engaged in coating technology research for more than 20 years, emphasized that inspection and debugging before use are indispensable links. First of all, it is necessary to confirm that the air source pressure is stable, and the air source pressure of the general industrial automatic spray gun should be controlled between 0.4-0.6MPa, and excessive pressure fluctuations will lead to uneven atomization of the paint. At the same time, it is necessary to check whether the connection between the gas pipe and the paint pipe is tight and whether there is any leakage to avoid potential safety hazards caused by sudden pressure drop.

Equipment cleanliness is equally important. Zhang Limin pointed out that if the spray gun was previously used for spraying other types of paints, it is necessary to thoroughly clean the paint channel to prevent chemical reactions caused by the mixing of different types of paints, causing nozzle blockage or coating defects. "Special solvents should be used for cleaning, and the steps of 'dismantling-soaking-rinsing-drying' should be carried out, especially paying attention to the cleaning of precision components such as nozzles and needle valves to avoid residual paint affecting the subsequent spraying effect." In addition, operators need to wear protective equipment, including gas masks, solvent-resistant gloves, protective glasses, etc., to protect their personal safety.

Core operating specifications: master the process and details

In the actual operation link, the standardization of the process and the control of details directly determine the quality of spraying. Li Hongmei, technical consultant of China Coating Industry Association, introduced that the operation of automatic spray guns needs to follow the core process of "parameter setting-test spraying-formal spraying-shutdown maintenance". In the parameter setting stage, it is necessary to determine the spray mode of the spray gun according to the paint type, workpiece material and spraying requirements, the common spraying modes include fan, round and oval, of which the fan mode is suitable for large-area flat spraying, and the circular mode is suitable for complex curved surfaces or local re-spraying.

The test spray link is a key step before the official operation. "The test plate with the same material as the workpiece to be processed should be selected for test spraying, and the thickness uniformity, gloss and adhesion of the coating should be observed." Li Hongmei gave an example that if the coating is found to be sagging after the test spraying, it may be that the paint viscosity is low or the spray gun is moving too slowly; If there are pinholes on the surface of the coating, it may be that the air source contains moisture or the paint is not stirred sufficiently. By adjusting the parameters in time through test spraying, quality problems in mass production can be effectively avoided.

During formal spraying, the distance between the spray gun and the workpiece and the movement speed need to be controlled. Under normal circumstances, the optimal distance between the automatic spray gun and the workpiece is 15-25cm, and the distance is too close to the coating to be too thick, and too far will cause paint waste and coating adhesion to decrease. The movement speed of the spray gun should be kept at a uniform speed, usually 30-60cm/s, and at the same time, it is necessary to ensure that there is an overlap of 1/3-1/2 in the adjacent spraying area to ensure that the coating is uniform and no leakage.

Key adjustment skills: Accurately control the three core parameters

The adjustment of the automatic spray gun is the core of achieving precise spraying, mainly focusing on three major parameters: paint flow, atomization pressure and spray amplitude. "These three parameters are interrelated and need to be coordinated according to actual needs to achieve the ideal spraying effect." Senior painting engineer Wang Jianjun dismantled this in detail.

The adjustment of the paint flow is achieved by adjusting the needle valve opening, the larger the needle valve opening, the larger the paint flow, and the thicker the coating. Wang Jianjun said that when adjusting, it is necessary to combine the coating thickness requirements, such as when using primer spraying, the paint flow can be appropriately increased to ensure that the coating has sufficient covering power; Topcoat spraying, on the other hand, requires a reduced flow rate to ensure a delicate and smooth coating. At the same time, the adjustment of the paint flow rate should match the movement speed of the spray gun to avoid problems such as "thick edges" or "thin spots".

The adjustment of atomization pressure directly affects the atomization effect of the coating. When the pressure is too low, the coating atomization is not sufficient, and the coating is prone to graininess; Too high pressure will cause the coating to rebound and waste, and the coating is prone to pinholes. "Generally speaking, the atomization pressure of ordinary solvent-based coatings is controlled at 0.3-0.5MPa, and the pressure of water-based coatings can be appropriately reduced to 0.2-0.4MPa due to their low viscosity." Wang Jianjun reminded that when adjusting the pressure, it is necessary to operate slowly to avoid damage to the internal components of the spray gun due to sudden pressure spikes.

The adjustment of the spray amplitude determines the size of the spraying range, which is achieved by adjusting the amplitude adjustment knob on the spray gun. When it is necessary to spray a large area of workpieces, the spray amplitude can be increased and the operation efficiency can be improved; When spraying small or special-shaped workpieces, the spray amplitude should be reduced to ensure that the coating adheres accurately to the surface of the workpiece. "While adjusting the amplitude, it is necessary to adjust the distance between the spray gun and the workpiece to ensure that the spraying area is evenly covered and avoid the edge coating is too thin."

Safety and maintenance: the key to extending the life of your equipment

"The safe use and daily maintenance of automatic spray guns are the basis for ensuring the long-term stable operation of equipment." Zhang Limin emphasized that it is necessary to keep the working environment well ventilated during the operation process to avoid safety accidents caused by the accumulation of paint volatiles; If you encounter faults such as gun blockage, you should turn off the air source and paint supply first, and then overhaul the equipment after the pressure is relieved.

Maintenance after downtime should also not be ignored. Li Hongmei suggested that after each use, the paint channel inside the spray gun should be cleaned in time to prevent the coating from curing and blocking the nozzle; For spray guns that are not used for a long time, special lubricating oil should be applied to the surface of the delicate parts, and then properly stored in a dry and ventilated environment to avoid moisture or mechanical collision. In addition, enterprises should establish a regular maintenance system to inspect the nozzles, needle valves, seals and other vulnerable parts of the spray gun, and replace worn parts in time to ensure stable equipment performance.

With the continuous upgrading of the painting process, the technology of automatic spray guns is also constantly iterating, but the use of specifications and scientific adjustment are always the core of the performance of the equipment. Industry experts agree that enterprises should strengthen professional training for operators, so that they can master the use skills and adjustment methods of equipment, achieve the double improvement of spraying quality and production efficiency through "human-technology collaboration", and promote the development of the coating industry in a more efficient, accurate and safer direction.