Airless spraying can be divided into hot spraying, cold spraying, electrostatic spraying, air subsidies and other types. Airless spraying technology and the development of equipment are closely linked.
(1) in the early stage of airless spraying, gear pump is used to pressurize the coating, but the pressure is not high, and the coating has poor atomization effect at room temperature. In order to make up for this defect, the paint is heated in advance and then sprayed out under pressure. This method is called hot spray airless spraying. Due to the large equipment, the use is limited, not widely used.
(2) later, the plunger pump was used to pressurize the paint, the paint pressure was high, the atomization effect was good, the paint did not need to be heated, the operation was relatively simple, this method is called cold spray airless spraying. High spray efficiency, less spray spray, can get a thicker film, the most suitable for large parts of the large area of spraying, so it is widely used. On this basis, pre-heating the coating to spray high viscosity paint and high solid paint, can improve the atomization effect, improve the decorative, to obtain a thicker film.
(3) electrostatic airless spraying is the combination of airless spraying and electrostatic spraying, which gives full play to the characteristics and advantages of both and improves the painting efficiency.
(4) two-component airless spraying is a new method developed to adapt to the spraying of two-component coatings.
(5) air-assisted airless spraying absorbs the advantages of air spraying to improve airless spraying. The spraying pressure is low and only needs about 1/3 of the general airless spraying pressure.