[Environmental protection coating practical class] Analysis and prevention of the disadvantages of reciprocating spraying

Compared with roller coating, reciprocating spraying is more suitable for the coating of flat and special-shaped parts.

01 cracking

cause

There are four main reasons for the cracking of the paint film after reciprocating spraying: one is that the moisture content of the substrate is too high, thermal expansion and contraction, the substrate and the sheet itself are degummed and cracked; the second is the MDF type substrate (medium density fiberboard) No special primer was used for sealing during construction, or the construction was carried out in a low temperature and high humidity environment; third, the product used in the repair of the substrate did not match the upper coating; fourth, the coating was forced to heat and dry before it was dry after the coating was applied online.

Preventive measures

The first is to do a good health treatment of the substrate before painting, and the moisture content of the substrate should be controlled at 8%~12%; the second is to carefully check the surface of the substrate.

02 whitish

cause

The whitening phenomenon of reciprocating spraying is due to the poor transparency of the coating itself; the second is the construction under high air humidity, or the one-time thick coating during construction; the third is that the infrared leveling temperature is too low after the coating is applied, and the solvent is not available.

Preventive measures

One is to select the appropriate coating product and design process according to the substrate or coating method; the second is the ambient temperature should not be lower than 5℃, the humidity should not exceed 85%, and the construction should be carried out by thin coating multiple times; the third is coating construction Then set the appropriate infrared leveling temperature according to the ambient temperature and humidity, and then heat to dry or solidify after the solvent is fully volatilized.

03 Orange peel

cause

The orange peel phenomenon occurs in reciprocating spraying.

Preventive measures

One is to slowly adjust the plunger pump pressure regulating valve to 0.

04 Sagging (flowing oil)

cause

The oil flowing during the reciprocating spraying process is mainly due to the low viscosity of the coating, the excessive coating amount, or the wrong angle of the spray gun.

Preventive measures

The first is to adjust the coating to a proper viscosity before construction; the second is to control the amount of coating; the third is to adjust and calibrate the tilt angle of the spray gun.

05 Uneven gloss

cause

There are three main reasons for uneven gloss in reciprocating spraying: one is the uneven mixing of the paint during paint mixing; the other is that the spraying air pressure is unstable during spraying or the gun caliber is inconsistent when two or more spray guns are in operation; the third is the infrared flow after the coating is sprayed.
The leveling temperature is too high and the infrared leveling temperature is unstable.

Preventive measures

The first is to mix the paint evenly when mixing the paint; the second is to ensure that the spraying air pressure is stable, and the caliber of the two or more spray guns is the same when operating; the third is to set the infrared leveling temperature according to the ambient temperature and humidity, and check whether the temperature is stable.

It is hoped that the majority of technical application engineers and home furnishing companies can have a deeper understanding of the disadvantages of reciprocating spraying through the above-mentioned learning, so that they can prevent them during the production process, improve production efficiency and improve product quality.