Company Info
Jiangyin Tianyu Nickel Screen Co., LtdAdd:No.121 Yongan Road, Changshou, Jiangyin City, Jiangsu Province, P.R.China
Tel: 86-510-86360099
Fax: 86-510-86966716
Email:barry@tynickelscreen.com
www.tynickelscreen.com
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Screen Engraving---TIANYU Rotary Screen Printing Solutions
Edit time: 2009-11-02
Screen Engraving The process of putting designs to be printed on both rotary and flat screens is known as screen engraving. The most widely used process for screen engraving is known as the lacquer method.
The overall process begins with the print design. Once the design is agreed upon, a textile artist separates the design into its individual colors. Each design component of each color is then made into a positive in black opaque ink on clear plastic film; the design is then reproduced color by color.
The flat or rotary screen is evenly coated with a liquid water-soluble photosensitive resin. The screen is dried and stored in the dark. When ready for engraving, the coated screen is then covered in the exact required location with the opaque design positive. High intensity light is then directed onto the screen. Wherever the light hits the screen, it hardens the resin and forms a water insoluble barrier. Where light is prevented from hitting the screen due to the design positive, the resin remains water soluble. After the proper amount of light exposure time, determined by the choice of resin, the screen is washed and dried. The design areas of the screen are opened, and print paste is allowed to flow freely through, but the non-design areas are closed. This method is used for nearly all flat screens.
Laser Engraving
For rotary screens, the most modern method of screen making is known as laser engraving. Here, the original design is digitized on a CAD (computer-aided design) system. Once again, a skilled textile designer separates each color of the design. At the same time, rotary screens are coated with resin, and the resin is completely hardened. The coated screen is then loaded on a mandrel, which is attached to a laser engraver. The machine engraves the screen using the digitized CAD print design data. Again only one color per screen is possible. The laser vaporizes the resin without damaging the screen material, which is normally nickel mesh for modern rotary screens. Laser engraving has greatly expanded the design possibilities for rotary screen printing. There is also a technique for engraving screens using nickel electroplating technology to form the design on the screen. This technology is known as the galvano method, but is now seldom used.
In the case of screen printing, some general print defects should be mentioned. They are as follows:
• Out of registration – pattern out of fit.
• Glue streaks – from the rubber blanket.
• Color smear.
• Color out – from a lack of print paste.
• Creased fabric.
• Pinholes in any screen.
• Damage to the screen leading to misprints.
• Lint on the fabric causes pick-off.
Remember, with print designs, color application must be correct the first time, because printing defects cannot be repaired. There have been many new and exciting improvements in screen printing in recent years, especially in the case of rotary screen machines. The use of microprocessor control systems have allowed for printing that is more accurate, has reduced print defects, and allows for increased productivity. New techniques for recovery and reuse of unused print paste have reduced dye and chemical costs and the pollution load on waste treatment systems. Overall, these improvements have produced machines capable of better quality printing at higher productivity with few defects and reduced environmental impact.
