<Metallic products paintung method>

one can use brush, roller, spray, airless kind of painting method, however according to the work condition one should choose a painting tool. Recently there are several painting method developed and amongst them the airless painting method is most popular and effectively used by many occasions. The simple explanation of each painting method will as follows.

1. brush painting : brush painting is slow in progress that this is used in small areas or when doing the finishing work. This method is used when it is too complicated to paint with roller, spray, airless. However if you want to paint the fragment thick, this method has the disadvantage of painting it over and over again for several times, not like airless spray.

2. Roller painting : this has faster speed than brush painting. However not like the brush painting, painting regularly around the uneven parts is very hard so should be really careful when painting on a surface is rough or irregular.

3. Air spray painting : this is the general painting method to paint large areas. While the spray is easy and cheap, in order to get the excellent fragment and appearance, the amount of air, pressure and the velocity must form a trinity. If one mispainted with spay painting method, the loss of paint will be really big and the paint will be sticking out from the product and appearance will not be seemingly pretty. Furthermore, if the operation got out of the way, the painting area will not be smooth and the paint might run, and there might be a pinhole in a fragment. The biggest disadvantage one could get by painting by spray is that the first painting job could not be done thick enough as to fit the paint viscosity, the solvent must be diluted. And also, when doing the large operation, it has no better feature than airless.

4. Airless spray painting : this method is not to mix the air straight to the paint to spray the paint. The spraying method uses the air pressure to eject through a special pipe or a tip. The size of a pressure used is calculated by the air pressure of a pump according to the internal air pressure rate. The pressure rate of a pump has 20:1 till 60:1, but normally 30:1 is used and zinc paint should use 45:1. The biggest advantage compared to the spray paint is that the loss of paint is small and can minimize the toxicity and explosion risk is small as well. Furthermore when spraying the paint, able to use small amount of solvent so that one can paint to a thickness of a humidity film and the efficiency of painting is high as well. As mentioned above, the spraying of paint is influenced by the specially designed types of tip. The tip or a nozzle is made up of tungsten carbide and the spray amount is changeable according to diameter of the pipe. Therefore there are many different types of tip which has different diameters and made of different angle. The selection of a tip depends on the spraying amount and the pressure and the diameter of a pipe to maintain the fixed spraying amount. That is, the speed of a paint influence the thickness of a fragment. Furthermore the angle of a tip should be chosen according to the width of a product. The tip which has pipe diameter from 0.009" to 0.0013" is best used to paint about 50micon(2mil). Moreover tip from 0.013" to 0.019" is when above 100-200micron(4-8mil), the tip from 0.019" to 0.023" is when above 200micron(8mil) is best suitable. The paint which has to be painted very thickly should be used with tip size of 0.060" diameter. Other than this, there are such tips that are made easy to clean the tips when painting commonly finishing paint. There is such paint that can make the appearance of a fragment beautiful using spray instead of airless. However the painting speed is so fast the this is used by metallic products which require ?? ?? ??? economic-wise and result-wise. Especially there are following advantages using airless rather than spray.

1) the adhesion efficiency is high : the paint from the nozzle will be pasted on the product without scattering off during the course.

2) The definite spray pattern : very little over spray. Therefore, will not pollute the environment.

3) Large capacity : just by painting once, you can get the fragment which is thick and the adhesion is excellent as well. Furthermore, the speed of painting is high.

4) High viscosity spray is possible : the area of paint applicable viscosity is wide.

4-1) high build paint airless equipment : high build paint is synthetic resins paint which, by painting once can get a thick fragment. Normally this has high viscosity and therefore should use a nozzle which has bigger hole rather than paint. And the parts to be used in this equipment has the following unique points.

- high capacity pressure and large current
- high internal pressure
- very small internal resistance
- suction availability is good

4-2) airless equipment for mineral zinc : this is a paint that is mixed by composition of silicic acid salts with zinc powder. And that the zinc particle will have the function of metallic products by electronically and chemically. Airless equipment should have the following feature to stabilize the slurry paint equally.

- Pump equipment should be made up of material that the zinc powder is hard to stick.
- The zinc powder will be separated from the mixed paint, so that it will not be precipitated.
- Seed part of the pump or spray gun structured in a way that the zinc powder will not clog them.
- Internal cleaning and disassembly cleaning must be easily done.

If we compare the airless operation with the former corrosion protection paint, will be as follows.

The tip sizes which could be used and pressured to the minimum by different types of paint are as follow.