Automatic spray gun common problem solving and maintenance

Abstract: The automatic Spray Gun is a spray device capable of automatically spraying raw materials. It is suitable for spraying small objects. It is suitable for spraying on hardware, toys, plastics, furniture, handicrafts, wood products, etc. Its main features are simple structure, easy operation and replacement. The color is easy, and the size of the scalloped surface can be adjusted according to the geometry of the workpiece to be coated, and the atomization effect is good. What is the principle of automatic spray gun? How to choose automatic spray gun? How to solve the common problem of automatic spray gun? How to use automatic spray gun maintenance?

[Automatic spray gun] Automatic spray gun principle Automatic spray gun selection Automatic spray gun Common problem solving and maintenance

Automatic spray gun principle

The inside of the automatic spray gun has a pneumatic piston mechanism with a stainless steel needle above the piston and a set of high tension springs behind the piston. When the compressed air stops supplying, the spring pushes the piston and the needle forward. When the needle and the nozzle are closely matched with high precision to block the passage of the liquid, when the compressed air starts to be supplied, the pressure of the compressed air pushes the piston open, so that a gap is formed between the needle and the nozzle to allow the liquid to be ejected. The liquid after the ejection is then brought into contact with the atomizing air to produce an atomizing effect.

Automatic spray gun selection

The choice of spray gun should pay attention to the fact that the primer mainly fills in the coating and increases the thickness of the coating. Therefore, the primer has a larger particle size, a larger viscosity, a larger specific gravity, and emphasizes that the amount of paint is large, so spraying The spray gun of the primer should be a large diameter nozzle, and the lower storage tank should be larger. Spraying the topcoat is highly demanding in terms of the degree of atomization, and a spray gun with a small diameter and a good atomization is often used. The nozzles of commonly used spray guns have different calibers, such as 0·6 mm, 0·8 mm, 1·0 mm, 1·2 mm, 1·3 mm, 1·5 mm, 1·6 mm, 1·8 mm, 2·0 mm, 2·2 mm. Various models such as 2·5mm can be selected according to the size of the sprayed paint and the object to be sprayed. For example: caliber 2·0—2·5mm, commonly used to spray coarser, more viscous primer or large-area spray; caliber 1·5—1·8mm, mainly used to spray topcoat; caliber 0· 6-1. 3mm, mainly used for spraying small parts or crafts.

Automatic gun adjustment

The adjustment of the spray gun is mainly to indicate the adjustment of the gas volume and the amount of paint. This is the two main factors that are interrelated. The gas output is too small, and it is not easy to atomize the paint liquid, so that the paint liquid is dripped and the film may be uneven. The amount of paint is corresponding to the amount of gas output. Before spraying, adjust the appropriate amount of gas and the corresponding amount of paint to make the paint liquid atomize well and spray it evenly on the object surface. To adjust the spray gun, listen to it (listen to the sound of the airflow, know the size of the airflow), and secondly (see the degree of atomization of the paint spray and the size of the fan-shaped area). Several important parameters of the spray gun are as follows: air pressure: the air pressure of the spray is generally (0.4--0.6Mpa); the spray width: the width of the sprayed surface is about 10cm; the spray distance: when spraying, the nozzle and the The distance between the sprays is 15-20cm; the moving speed: the moving speed of the spray gun is generally 30--60cm/sec; the overlapping range: the overlap range of each gun during spraying is 1/2--1/3 (crack paint) Except); spraying angle: the angle between the nozzle and the object to be sprayed is generally 90°.

Automatic spray gun common problems and solutions

Some problems sometimes occur in the process of using the automatic spray gun. Now, the phenomenon of the spray gun is analyzed in detail, and the cause is analyzed according to the phenomenon, and the solution is found.

Phenomenon: The shape of the spray frame is biased to one side. Cause: The central hole of the air cap or the atomization hole is blocked. 1. Clean the atomizing cap 2. Replace the atomizing cap.

Phenomenon: Left or right cause: 1. Blocking of the control hole on the side of the air cap 2. Damage to the air cap: 1. Clean the atomizing cap 2. Replace the atomizing cap

Phenomenon: The center of the spray width is too thick. 1. The viscosity of the sprayed paint is too high 2. The spray pressure is too low 3. The diameter of the nozzle and the thimble increase and decrease due to wear.

Countermeasures: 1. Reduce the viscosity of the paint 2. Increase the spray pressure 3. Replace the nozzle set

Phenomenon: Causes of spray splitting: 1. The viscosity of the coating is too low 2. The spraying pressure is too high 3. The inner diameter of the fan control hole is too large 4. The coating is not enough. 5. The atomizing air passage is blocked. 1. Adjust the viscosity of the coating 2. Spray pressure 3, replace nozzle set 4, add enough paint 5, clean the air passage of the spray gun

Phenomenon: Causes of jumping gun: 1. The nozzle is not tightened or not installed. 2. The needle seal kit is loose. 3. The connection nut of the spray gun is loose (the lower pot spray gun). 4. The paint in the pot is insufficient. 5. The nozzle set is damaged. Tight nozzle or clean and install nozzle set 2, tightening thimble seal kit 3, tightening connection nut 4, replenishing paint 5, replacing nozzle set

Phenomenon: The weight of the spray frame is heavy or heavy. Cause: 1. There is debris on the air outlet of the nozzle, thimble or air cap. 2. Air cap or nozzle damage measures: 1. Clean nozzle set 2. Replace nozzle set

Phenomenon: The paint can not be sprayed or a small amount of paint is caused. 1. The air refill hole of the gun lid is clogged or the air cap and the suction tube are severely blocked. 2. There is no paint in the pot. 3. The thimble stroke is too small. Countermeasures: 1. Clean the lid Air replenishing hole, air cap and suction tube 2, replenishing paint 3, rotating paint flow adjustment knob to increase the stroke of the needle valve

Phenomenon: Causes of leakage of paint at the nozzle: 1. The thimble seal nut is too tight 2. There is foreign matter inside the nozzle port 3. The nozzle and thimble are not matched or damaged 4. The ejector pin return spring is broken or not installed. Thimble sealing nut 2, cleaning nozzle 3, replacement nozzle set 4, replacement ejector return spring or mounting ejector return spring

Automatic gun maintenance

After the spray gun is used, spray it with the thinner of the sprayed paint until the spray coating channel is cleaned. Otherwise, the dry solid blockage of the gun will affect the normal use of the gun. Specific cleaning method; close the compressed air, remove the storage tank, pour the paint inside the paint into the storage tank, pour the paint in the tank into the container; pour about 1/4 volume of solvent into the storage tank Rinse, install the paint can, turn on the compressed air, repeat the rock and roll several times; remove the nozzle, wash it with solvent and install it; wipe the paint on the gun body.

When washing the spray gun, pay attention to the following points: use a soft brush when brushing, do not use metal brushes, do not use hard objects to smash, scrape, prevent wear nozzles, change the shape of the jet; avoid the spray gun directly in the solvent, Anti-residue paint attached to the machine and the lubricant on the gun can be wiped off with a soft cloth dampened with solvent; the knurled parts on the gun are adjusted by hand to avoid the use of Pliers tools; regular needles and guns Lubricate the oil at the pin; apply light grease or Vaseline lubrication needle valve and needle valve spring regularly. Do not use silicon-containing oil.

Spray booth seal

In order to make the air in the spray booth clean and dust-free, the doors and windows of the spray booth should be equipped with air purification and filtering devices. The 200-mesh silk cloth is usually installed on the doors and windows, so that the air entering the spray booth is filtered and dusted to achieve purification. purpose. In front of the workbench is a water curtain machine and an exhaust fan, which can make the flying paint mist generated during the spraying operation be discharged out of the room by the exhaust fan, keeping the indoor air fresh, which is beneficial to the health of the operator and prevents the flying paint. The mist splashes on the surface of the coated object after spraying, ensuring that the surface to be coated is smooth and smooth.

Editor in charge: Zhao Hongli

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