The main materials for making nameplates are aluminum, copper, stainless steel, and aluminum is used in the largest amount. There are also plastic, polyester, paper, etc.
Aluminum signs are one of the most widely used types of signs. They are beautiful, bright, hard, wear-resistant, widely applicable, and used in large quantities. Used in machinery, electronics, instruments, meters, household appliances, daily hardware, watches, daily cosmetic packaging, etc.
There are many methods for pre-treatment of aluminum substrates. Depending on the purpose, they mainly include degreasing, sandblasting, wire drawing, polishing, and oxygen grease.
1. Oil removal: In order to make the surface of the aluminum substrate have a certain degree of ink affinity, the oil layer and oil stains on the surface need to be removed. You can wipe it with cotton gauze dipped in gasoline. Alkaline solutions can also be used for chemical degreasing, such as sodium sulfate 30-50 g/L, sodium phosphate 40-60 g/L, sodium silicate 10-15 g/L, and soaked in a temperature of 60-70 degrees for 2-5 Removes oil in minutes.
2. Sandblasting: Sandblasting is to improve the adhesion between ink and metal materials. A special sandblasting machine is usually used for blasting. If the aluminum plate is 0.5-1 mm thick, the diameter of the sand particles used for sandblasting 0.05-0.15 mm, river sand can also be used, filtered through a screen before use.
Refer to the detailed information
3. Wire drawing: Also known as twist processing, it is a method of mechanical friction on the surface of the aluminum plate to produce fine straight lines. It is a newer surface decorative treatment process that can overcome defects such as scratches on the aluminum surface. Improve material usage. There are two types of wire drawing: thick wire and fine wire. Generally, a stainless steel wire brush with a diameter of 0.1 mm or a scouring pad belt brush is used. Nylon abrasive belts can also be used for processing.
4. Polishing: It is to overcome the surface defects of aluminum-based materials and improve the surface finish. Polishing is divided into mechanical polishing and chemical polishing. Mechanical polishing uses a cloth wheel polishing machine. Chemical polishing is mostly carried out in acidic solutions, such as 15% sulfuric acid and 10% nitric acid, at a temperature of 90-100 degrees and a time of 2-3 minutes.
5. Oxidation: There is residual polishing soap on the polished surface of the aluminum plate. Use a piece of yarn dipped in gasoline to wipe it off, then perform chemical degreasing, and then immerse it in a nitric acid solution (1:1 ratio of nitric acid to water) ), take it out after 10 minutes, and then put it into the oxidation tank for electrochemical oxidation. Oxidizing solution formula: nitric acid 160-200 g/ml, temperature 10-20 degrees, time 30 minutes.
The oxidized aluminum plate is fully washed and dried, and a uniform pore oxide layer, that is, an oxide film, is formed on the surface. Contamination by dirt should be avoided. It is best to print the oxidized aluminum plate immediately. If it cannot be printed immediately, it should be wrapped with a soft paper separator or placed directly on the air-drying rack. The storage time should not exceed one week.
The oxide layer on the surface of the aluminum plate can absorb dyes, moisture and other salts, so do not touch the surface with your hands or oily things when screen printing. When the ink is printed on the oxide layer, the ink penetrates into the pores. The heating in the next step accelerates the penetration of the ink into the pores until all the surface pores covered by the ink are filled.