The distance between the nozzle of the spray gun and the surface of the workpiece

The spraying distance generally refers to the straight length from the air cap atomization hole of the spray gun to the surface of the object to be sprayed, which is generally between 150-300mm. To obtain a wetter, darker, and thicker coating, the distance can be closer; To obtain drier, lighter, and thinner coatings, the distance can be farther.

The distance between the spray gun is too close, the spraying pressure is too high, and the recoil force is also large. This can easily lead to uneven coating and sagging, and the spraying amplitude is small, resulting in excessive spraying and thick coating on the coated area.

The distance is too far, the spray pressure loss is large, the paint is prone to loss and the spray amplitude is too large, the paint adhesion is low, the paint surface is rough, and the coating does not meet the thickness requirements.

The angle between the spray gun and the surface of the workpiece

When spraying, the spray gun must be kept perpendicular (90 °) to the surface of the workpiece. To achieve this, the spray gun must be kept at a right angle to the sprayed plane throughout the entire process of spraying, and the arm must move parallel to the surface of the sprayed workpiece. It is definitely not allowed to sway in an arc with the wrist or elbow as the axis.

For products with curved surfaces, gesture adjustments should be made according to the curvature of the product. Remember to keep the spray gun perpendicular to the center point of the product.

Never use your wrist or elbow to make curved swings, as shown in the following picture: the left side is correct, the right side is incorrect.

The direction of the spray gun operation should always be parallel to the surface of the object being coated and perpendicular to the spraying fan to ensure the uniformity of the coating. The running speed of the spray gun should be stable, generally maintaining a speed of 300-400mm/s for uniform movement.

Moving the gun too quickly: it will make the paint too dry, the surface rough, and orange peel;

Slow movement of the gun: it can easily cause sagging, and when spraying metal paint, it can easily cause silver accumulation and cloud formation;

Operation of spray gun trigger

Due to the large flow of paint when the trigger is tightened, in order to avoid the accumulation of paint sprayed at the edge of the workpiece at the end of each gun stroke, it is necessary to slightly relax the trigger at the end of the gun stroke to reduce the paint supply.

Spray path

The spraying methods include vertical overlapping method, horizontal overlapping method, and alternating vertical and horizontal spraying method. The spraying route should be carried out in the order of high to low, left to right, top to bottom, and from inside to outside. At the end of the journey, turn off the spray gun. The second unidirectional movement of the spray gun is opposite to the first one, and the nozzle is flush with the edge of the paint film strip in the first journey, so that the upper half of the paint film strip in the second stroke overlaps with the lower half of the paint film strip in the first stroke. The overlap of the paint film strips in the two strokes should be about 1/3 or 1/2, as shown in the figure:

There should be a overlap amount or overlap rate between adjacent spraying strokes, and the overlap rate should reach 50%~67%. If it is too fast or there is not much overlap, it is difficult to obtain a smooth paint film.