Anyone who has ever had a metal logo knows that the metal logo usually needs a concave-convex effect. On the one hand, it makes the logo have a certain three-dimensional and hierarchical sense. What is more important is to avoid blurring and even fading of the graphic content caused by frequent wiping. This concave-convex effect is generally achieved by etching (chemical etching, electrolytic etching, laser etching, etc.). Among various etching methods, chemical etching is the mainstream, so it is called "etching" regardless of whether it is in such literature or at the beginning of the line. If there is no other explanation, it means chemical etching. The manufacturing process of metal signs includes the following three main links: 1. graphic formation (also known as graphic transfer); 2. Pattern etching; 3. Graphic shading.
1. Graphic formation
There is no doubt about etching images and text content on blank metal plates. First, the image and text content should be formed (or transferred to the metal plate) with certain materials and methods. Generally, images and text can be formed in the following ways:
Computer engraving is to design the required graphics or text on the computer, and then use the computer engraving machine to carve the graphics and text on the adhesive, paste the engraving on the blank metal plate, remove the self-adhesion of the parts to be etched, expose the metal texture, and then etch. This method is still widely used, with the advantages of simple process, low cost, and convenient operation. TLimited accuracy: generally, the minimum text engraved by the engraving machine is about 1 cm, and the smaller text will be deformed and cannot be used. Therefore, this method is mainly used to make metal signs with large pictures and texts.
1. Photosensitive method (divided into direct method and indirect method)
① Direct method: first convert the graphic content into black and white film (film), then apply a layer of photosensitive anti-corrosive ink on the blank metal plate, and then dry it. After drying, the film is covered on the metal plate, And put it into a special exposure machine (exposure on the printing machine, and then develop it in a special developer. After development, the photoresist ink of the unexposed part is dissolved and washed away to expose the real surface of the metal. Due to photochemical reaction, the photosensitive photoresist ink of the exposed part forms a layer of adhesive film, which is firmly attached to the t. He uses metal plates to protect the metal surface from corrosion.
② Indirect method: indirect method is also called silk screen method. First, the graphic content is made into a screen printing plate, and then a anti-corrosion ink is printed on the metal plate. In this way, an anticorrosive coating with patterns is formed on the metal plate, and then dried, etched and polished... The selection principle of direct method and indirect method: the direct method has high graphic accuracy and good quality, and is easy to operate, but in the case of large quantities, the efficiency is low, and the cost is higher than the indirect method. The indirect method has poor graphic accuracy, but low cost and high efficiency. It is suitable for mass use.
2. Pattern etching
The purpose of etching is to make the place with pictures and words on the metal plate concave (and vice versa, to make the mark appear concave and convex effect, first for the sake of beauty, and second for the purpose of making the pigment filled in the picture and text lower than the mark plane, so as to avoid frequent erasing of color. There are three main etching methods: electrolytic etching, chemical etching and laser etching.
3. Graphic shading (color fill and paint fill)
The purpose of color is to make the graphic and text of the logo form a sharp contrast with the layout, and enhance the eye-catching and aesthetic sense. The main methods of coloring are as follows:
1. Manual coloring (Commonly known as painting, brushing teeth or painting: fill the etched pits with needles, brushes, brushes and other tools. This method used to be used in the badge and enamel process. Its characteristics are primitive process, low efficiency, large workload, and need skilled work experience. However, at present, this method still occupies a place in the identification process of thod, especially those with trademarks and there are many colors near the trademarks, and they each other Very close. In this case, manual coloring is a good choice.
2. Paint: self-adhesive adhesive is used as anti-corrosion protective film for labels. After etching, the label can be cleaned and dried, and then painted on the sunken pictures and words. The equipment used for painting is air machine and spray gun, but self-painting can also be used. After the paint is dry, you can tear off the adhesive protective film, so that the excess paint sprayed on the adhesive will be removed naturally. For the mark with photosensitive anti-corrosive ink or silk screen anti-corrosive ink as the protective layer, the protective ink must be removed before painting, because the ink protective layer cannot be torn off like the self-adhesive protective layer, so the ink must be removed first. The specific method is as follows: after the mark is etched, remove the anticorrosive ink with liquid medicine first → wash → dry, and then evenly spray the place that needs to be colored (that is, the place with pictures and words) with a spray gun. Of course, paint will also be sprayed where it is not necessary, which requires the next process: paint scraping and polishing.
Paint scraping is to use metal blades, hard plastic and other sharp things to stick to the surface of the sign to scrape off the excess paint on the surface of the sign. Grinding paint is to use abrasive paper to grind off the excess paint. Generally, paint scraping and polishing are often used together. The efficiency of painting method is much higher than that of manual painting, so it is still widely used, and is the most widely used method in the signage industry at present. However, because the general paint is diluted with organic solvent, the air pollution is serious when painting, and the staff are suffering from it. What is more annoying is that the later paint scraping and polishing are very troublesome, which will scratch the paint film carelessly, and then have to be repaired manually. And after the paint scraping, the metal surface needs to be polished, polished and baked, so the industry is quite headache and helpless.
3、 Electrophoresis coloring: its working principle is that the charged coating particles swim to the electrode with opposite charge under the action of current (It is quite like swimming, so it is called electrophoresis. The metal workpiece is immersed in the electrophoretic paint solution. After being electrified, the cationic paint particles move to the cathode workpiece, and the anionic paint particles move to the anode, and then deposit on the workpiece to form a uniform and continuous coating film on the surface of the workpiece. Electrophoretic coating is a special method of coating film formation. It uses environment-friendly electrophoretic paint, which is non-toxic and harmless, and uses water as the diluent, without painting, spotting, and brushing, which saves the headache of scratching The painting, grinding and polishing processes are fully automatic and very easy. Fast coloring speed, high efficiency, One batch can be sent every 1~3 minutes (A few to dozens of signs have been painted with electrophoretic paint. After cleaning and baking, the paint film is uniform and bright, and it is very firm and not easy to fade. The paint cost is low, about 0.07 yuan per 100CM2. What's more gratifying is that the problem of coloring mirror metal signs after etching, which has troubled the sign industry for decades, has been easily solved by it! As mentioned earlier, metal signs generally need to be painted, then scraped and polished, but mirror metal materials (For example, mirror stainless steel plate, mirror titanium plate, etc. are as bright as a mirror, which cannot be scraped or polished when painting, which sets a huge obstacle for people to make mirror metal signs! This is also the main reason why high-grade and bright mirror metal signs (small pictures and texts have been rare).