Generally, it refers to the secondary processing of plastics, which refers to the process of secondary processing of the surface of plastics after molding to make its appearance meet the expected requirements, and its surface and internal surface meet a specific performance.The process includes such processes as machining, mechanical connection, surface physical and chemical treatment, welding, bonding, surface modification, printing, surface metallization, etc.Only through these processes can complete plastic molding and production of plastic products be formed[1]。
Processing technology
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The secondary processing technology of plastics includes: oil spray screen printing, pad printing, bronzing, electroplating, ultrasonic, and radium carving.
1. Oil spraying: it is to spray paint on the plastic surface or internal surface.
2. Silk screen printing/pad printing: printing the required text on a specific location on the surface of plastic products. The difference between silk screen printing/pad printing of patterns is that pad printing is mostly used for irregular uneven or large arc surfaces. Usually, it is difficult to complete the silk screen printing process. The pad printing is a process method that has the characteristics of stability and high efficiency.
3. Stamping: The metal part on the stamping paper is covered on the surface of the product under high temperature and pressure through the stamping machine, so that the surface has metal characteristics.
4. Electroplating: ultra wave, radium carving.
Common quality defects in plastic secondary processing
2. Common quality defects of gilding: dust spots, wrinkles, dents, pits, gilding edges, gilding not to the edge, scorching, and dropping gilding.
3. Common quality defects of screen printing/pad printing: ghosting, fuzzy font, broken lines, uneven font thickness, color difference, and screen printing loss.
4. Flying oil: refers to paint adhesion on non fuel injection parts, which is generally caused by the inconsistent size of the fuel injection fixture with the product, improper fixture design, or loose fixtures that are not clamped in place.
5. Oil accumulation/oil accumulation: it refers to the excessive accumulation of paint caused by too thick oil injection, which is generally caused by repeated spraying of products. At the same time, oil accumulation/oil accumulation causes surface wrinkling, orange peel, or even bright surface.
6 Less oil/thin oil: incomplete spraying results in incomplete surface coverage, even exposed background color (plastic natural color), inconsistent surface spraying thickness, which can be tested with a film thickness gauge. At the same time, it is the same as improper operation gesture or manipulator program setting, which results in less oil or no oil in a certain area of the product. Generally, at the corners of the product, there are structural blocking parts, such as hole locations, slot locations, and around round feet. At the same time,Low/thin oil causes injection color difference.
7. Dust wire/dust spot: refers to that after the product is sprayed, there are fine particles and linear sundries on the surface.The reason is that the on-site working environment is poor, and the product surface is not clean. The improvement method is to strengthen 5S management, improve the on-site working environment, and clean the plastic surface.
8. Scorching: refers to the phenomenon that the surface of the product becomes white and shiny after spraying, which mostly occurs in silver oil and silver flashing products. It is usually easy to see through the black box inspection. The causes of the defects are various, including obvious air lines, light prints, materials, paint coverage, and even the spraying action may cause scorching.
9. Color difference: it refers to the deviation between the spray color and the sample plate, which is mostly due to the poor quality of the stain paint itself, improper paint preparation, and non-standard spray action (one more shot, one less shot, or the deviation of the background color of the plastic parts).
10. Oil residue: it is similar to dust filaments and dust spots, but the difference is that oil residue is accumulated after the paint flute is hardened, for example, the fixture is not cleaned for a long time, and the paint on the fixture is adhered to the product after curing.
11. Oil loss: the paint is separated from the product adhesive layer.Oil loss includes test oil loss, collision oil loss, etc. The reason is that the paint itself is not dry, the furnace temperature is short, the temperature is low, and the products are stacked disorderly.
12. Grinding mark: the product surface is painted after repair, and there are grinding marks on the surface. The defective scene image that cannot be covered by spraying again is white during black box inspection.
13. Ghosting: It refers to the obvious double shadow phenomenon that is not printed in the original position (deviation) when printing again due to unclean cleaning during the rework of silk screen/pad printing defects.
14. Font mold: the ink is opened thinly, the screen board is not cleaned frequently, and the surface texture of the product is coarse, resulting in blurring after screen printing/pad printing.
15. Broken line (incomplete font): it is because the screen board is not cleaned, the silk screen is not strong enough, or the scraper is not completely scraped when the staff is working, which causes the font not to be printed[1]。
