Spray enamel coating in wet process
Spray enamel coating is to compress air to spray enamel slurry or powder to body metal. Spray enamel coating in wet process is prevented first, then in the mid of 20th century, dry powder spray is prevented, it’s to use electrostatic adsorption to let enamel powder adhere on body metal. There’re mainly 2 ways of spray enamel coating in wet process: handwork spraying and automatic machine spraying.
1, Handwork spraying
Handwork spraying can be applied to almost all product, especially for those which has very elaborate line and pattern for decorations and with very complex shape. The weakness for handwork spraying is low efficiency, high labor strength for the workers. And the quality of final products depends much on workers’operation proficiency
For spray enamel coating in wet process, the caliber of spray gun can be adjusted according to types of enamelware and property of enamel slurry. Enamel slurry can be supplied by cup on spray gun or peripheral express tank. For product with little usage amount and need to change frequently, the cup on spray gun is suitable. For example, enamel cookware which always need to coated with patterns in many colors for decorations. When the using amount of enamel slurry is very huge and with single type, peripheral express tank will be better. For example, stove grill, cast iron cookware with single color and big architecture panels. For these, enamel slurry in express tank will easily sink, so the enamel slurry inside need to be swigged constantly to keep its balance, to prevent any bad effects due to the sink of enamel slurry.
To achieve better atomization effect, enamel slurry for spray enamel coating in wet process should be finer, but also need to pay enough attention to the quality after drying and firing. To prevent cracking and shrink of enamel surface. The specific gravity of enamel slurry better be higher. As with higher specific gravity, spraying time can be reduced. For single faced coating, required coating thickness can be attained as long as spray gun passed it for few times.
2, Automatic machine spraying
For big objects, automatic machine spraying should be applied.
The products will be horizontally hanged and pass through a channel with many spray gun around. Spraying can be done automatically when the product passed through.
Enamel pots should be placed on the transmit line and sprayed with many spray guns. Every spray gun should be adjusted with suitable anger and be fixed. To coating every face of product with required standard. When product pass through the scope that the spray gun can reach, except to go forward, it should also turn around, to ensure full coating. Enamel slurry supply system of automatic spraying machine usually include express tank, tube, liquid level control, and filter sieve etc…supply system will transport enamel slurry to spray gun. Traditional supply system is express tank, it can be used for store and also offer high express to transport. Then develop to store tank with diaphragm pump together. This makes it more convenient for continuous enamel slurry supply or change enamel slurry types and easy to clean after work.