The Spray Gun is a tool that atomizes and sprays the paint onto the surface of the substrate after mixing the paint with compressed air.
Spray guns are divided into internal mixing type and external mixing type . As shown in Figure 1, the nozzle is two concentric circles, which constitute the paint and air passage, the inner circle is the paint outlet, and the gap between the inner and outer circles is only about 0.3mn.
Figure 1 Classification of Spray Guns
The internal mixing type Spray Gun is that the paint and air are mixed inside , which is suitable for higher viscosity, thick film paint, and also suitable for adhesives, sealants, etc. The spray pattern is limited to a circle, which is suitable for the spraying of small objects and colorful paints. The paint mist sprayed by this Spray Gun is softer, but the production capacity is not large. The external mixing type is the mixing of paint and air on the outside of the air cap. It is suitable for paint with low viscosity and easy flow and atomization, and spray shape can be adjusted. It is suitable for large, small and various shapes of workpieces. Therefore, external mixing is generally used. Hybrid Spray Gun.
② Spray guns are divided into suction type , gravity type and pressure feeding type , see the table for details.
| Spray Gun type | Structural features | advantage | defect | The main purpose | main model |
| Suction type | The paint can fits under the nozzle | Good operation stability, easy to change paint color | It is difficult to spray on the horizontal surface, which is greatly affected by the viscosity of the paint | Small area construction | PQ1, PQ-2, GH-4, KP-30 |
| Gravity | The paint can is mounted above the nozzle | The Spray Gun is easy to use and has little effect on viscosity | Poor stability, difficult to operate on the back | Small area construction | KP-10 |
| Pressure feed | There is also a pressurized box to automatically supply paint | Several Spray Guns can be used , and the paint capacity is large | Fast paint replacement, troublesome cleaning | Continuous spraying of large areas | KP-20 |
The capacity of the suction Spray Gun paint tank is generally about 1L, which is suitable for small batch discontinuous operation and repair paint. The paint output of the gravity Spray Gun is larger than that of the corresponding suction Spray Gun, and the capacity of the paint tank is generally 250 ~ 500mL. The paint tank capacity of this Spray Gun is small, which is suitable for the occasions where the amount of paint is small and the color is changed frequently. There are three ways to supply the paint of the pressure-feed Spray Gun: supply the paint from an external compressed air booster tank, usually a 20-100L pressure tank; rely on a small air pressure pump to press out the paint from the paint tank and directly supply the Spray Gun; The viscosity of the paint is adjusted in the paint room, and the pump is used to transport the paint into the paint pipeline to form a circulation loop . The paint is continuously circulated in the pipeline and returned to the paint supply tank. Where the amount of paint is large and the color change is small, it is advisable to use a pressure-feed Spray Gun, and the paint is supplied by a paint booster tank or a paint delivery system.
The Spray Gun body is light and compact, the amount of sprayed paint and compressed air is also reduced, and the operating efficiency is reduced. It is not suitable for large-scale assembly line painting production. Large-scale Spray Guns are used on mass production lines , and small Spray Guns are suitable for coated objects with very different convexities and concaves .
