Our common metal materials, such as some basic accessories made of metal, are often silver-white, which may not be very beautiful in terms of appearance. In addition, because of the Disadvantages, so after later use, there will be some malfunctions on the metal surface, including metal rust, etc., so we need additional processing and treatment, including metal surface spraying, etc. Before doing this, it is necessary to learn and understand something like the following Information about equipment commonly used in the metal surface spraying process and an introduction to the basics of the process.
1. Metal surface spraying process
The main process of spray painting is as follows:
Cleaning the surface→Spraying the first coat of primer→Batch of the first putty→ Frosted paper → Batch the second coat of putty → Sandpaper and polish → Spray the second coat of primer → Batch the third coat of putty → Sand with water sandpaper → Spray the third coat of primer → Sand with water sandpaper → Spray the first coat of paint → Polish with water sandpaper → Spray the second coat of paint → polish with water sandpaper → spray the third coat of paint → apply sanding wax and oil wax → polish.
1. Primer
The primer for spray painting can be phenolic primer, ester primer, nitro primer, alkyd primer, etc. Among them, alkyd primer has Good adhesion and anti-rust properties, and good combination with nitrocellulose varnish. The primer can be thinned with matching thinner or rosin water, turpentine, etc.
2. Putty
The putty ratio for spray painting is as follows:
Gypsum powder? 30
White thick paint? 15
p>Mature tung oil? 10
rosin water? 6
Water? Appropriate amount
Liquid drier? 0.25～0.5
< p>After the putty is mixed thoroughly, horn pieces or scrapers can be used to embed the flat surfaces, and rubber can be used to embed the curved surfaces and corrugated corners. Do not scrape the putty back and forth too much. The first putty is slightly thicker, and the second and third putty are slightly thinner. After the putty dries, sand it down to make it smooth.3. Spray painting
The equipment used for spray painting includes air pumps, air filter tanks, air ducts and spray guns. Commonly used spray guns include suction type, nozzle type and flow type.
When spraying, press the handle and the compressed air will be sprayed out from the air outlet, so that the paint liquid can be sprayed evenly on the surface from the paint outlet.
The distance between the spray gun and the object surface should be controlled between 200 and 300mm. The first spray should be closer, and each subsequent spray should be slightly farther.
The air pressure should be maintained between 0.3 and 0.4MPa, and gradually decrease after the first spray.
When using primer and spray paint, diluent must be used to dilute it. In the absence of a viscometer, diluent can be added based on 100% of the weight of the paint liquid so that the paint liquid can be sprayed out smoothly. , not too thin or too thick. Alkyd primer can be diluted with rosy water; nitro varnish can be diluted with banana water.
When spraying the first coat of nitrocellulose varnish, the primer and putty are oily and are easily dissolved by thinner to produce bubbles and wrinkles, so the spray speed should be slightly faster and the spray should be thinner. After spraying it once, wait for it to dry, sand it with water sandpaper and spray it again.
2. Commonly used equipment for metal spraying
Arc spray guns are commonly used in the machinery industry and are suitable for metal wire spraying. Flame spray guns are suitable for spraying metal wire as well as cermets and refractory oxides. Plasma arc spray guns and plasma spray welding are suitable for spraying various types of powders. Arc and flame spray guns are used for general corrosion prevention and repair. Among them, those used for spraying zinc and aluminum can spray more than 200 kilograms per hour; they are used for other functional purposes, such as those that require dense coatings and high adhesion requirements, etc. High-energy plasma spraying and vacuum high-energy plasma spraying are used. The spray speed of the explosive coating equipment can reach 2 to 3 times the speed of sound, and is suitable for spraying metals, especially cermets and refractory oxides.
In order to ensure an economical and high-quality metal spray coating, in addition to the appropriate selection of spraying methods and spraying materials, pre-spraying and post-spraying treatment are also necessary steps. In order to improve adhesion, functional metals often need to be sprayed before spraying, and then sprayed with a bonding layer (nickel, molybdenum, etc.), or threads or grooves can be machined on the surface to be sprayed, followed by spraying or spraying. Bonding coating. After spraying, the quality of the sprayed coating shall be inspected, and necessary sealing treatment and corresponding finishing processing shall be carried out.
The above is a detailed introduction to the commonly used equipment and processes for metal surface spraying. From this, we can know that as a representative method in metal processing operations, spraying on metal surfaces Specific coatings can not only enhance their aesthetic effect, but also play a protective role to prevent losses and troubles caused by later metal rust. In addition, it can be further discovered that the effect of metal surface spraying depends on the material. The selection of equipment and the practice of process operation methods are both critical. You can refer to the above to learn in advance to prepare for emergencies.