Airless and air assisted spray gun

atomization in the airless spray gun
 

Airless spray gun

The airless spray gun has different atomization method with the air spray. If the in the air spray gun, the material atomization is the result and together with the flow of compressed air, then in the airless spray gun the atomization of materials is occur without air mixed with the finishing material (airless). The material is pressed with a very high pressure and then passed through a small orifice, and then atomization occurs. The pressure required is very high, up to 1000 psi (68 bar). Therefore the airless spray gun needs high pressure pump and material hose that can withstand the high pressure. This equipment can generate the high speed and the efficiency of transfer material is higher than the air spray.
Another advantage of this airless spray is that he can be used for application materials with high viscosity. The disadvantages of this equipment is the spray result is not too good and its low flexibility. It cannot give the perfect layer as the air spray because the atomization of the material is not as perfect as the atomization with air spray. It also has limitation in the adjustment and setting. The spray gun dose not has the screw to adjust the air volume and pressures, either the volume control. The liquid volume is set by the orifice size, while the air pressure need to be set at the minimum pressure to do the atomization. The setting to adjust the width of spray fan is also very limited. It is more suitable to do the finishing process to the mass production at which do the big volume product with the similar form and size.

 
The airless spray gun is usually only used for sealer application, which is followed by sanding and then layer with another coating material. Currently finishing furniture industry mostly use the air assisted airless spray gun or air mixed spray gun, the modification of the airless spray gun.

Air assisted airless (air mixed) spray gun

The air assisted airless spray gun is the development of the airless spray gun. It is the airless spray gun but with pressure air flow to improve the atomization of material. The atomization results obtained is better than airless spray gun, though not as good as the air spray. This make the air assisted airless spray gun is more widely used in furniture finishing industry. The use of air assisted spray gun is mainly to the sealer and top coat application. This equipment can do a faster job compare with air spray gun. The atomization is not as perfect as the air spray gun but is still acceptable in the furniture finishing industry. This equipment is still possible to spray glaze but it is not available to spray stain.
The disadvantages of the air assisted airless spray gun is his less flexibility compared with the air spray gun. In the air spray gun, the operator can easily adjust the volume of material, wide fan spray and pressure air to get the best spray result. In the air assisted or airless spray gun, the volume of material cannot be adjusted because it depends on orifice size that was installed in the spray gun. Limited adjustment can only be done to the wide fan spray and the air pressure that are added to assist atomization. The limitations the air assisted airless spray gun, make this equipment is not possible to do medium wet spray or dry spray. The uses of this equipment are only for spray base coat, paint, sealer, top coat and glaze application. For the stain application that need more briefly adjustment we still use the air spray gun.