Read on to find out more about the latest technologies available for this screen-printing specialty.
By Harald Gavin
Mechanical drives allow for the highest production speeds. They are rigid and durable enough to handle the demand. Machines with either one- or two-up operation allow for production speeds up to 100 items/min or 160 items/min, respectively (Figure 2). Mechanical drives resist wear and ensure a long machine life cycle, but machines equipped with these drives are designed for specific types of products and support a limited range of product shapes.
Improved productivity results not only from the faster operating speeds of these machines, but also from enhanced engineering that eliminated process steps, such as re-registering items in each printing station to achieve accurate color-to-color registration. In this situation, rotary indexing tables are used to hold an item in its fixture while the item is moved through the machine. To maintain tight control of the angular position of each fixture on the indexing table, the fixtures remain in positive contact with the main drive gear. As a result, the positions of the fixtures are known at all times, which makes it unnecessary to re-register items in the printing stations. The time saved in re-registering leads to shorter printing cycles and increased production speed. Only the orientation of the item is adjusted for correct image positioning, and this adjustment does not affect throughput, even if it is performed in a separate station (Figure 3).
Servo systems use a set of parameters to simulate gear boxes or make servomotors follow electronic CAM profiles. Servo systems can quickly accept new parameters that change positioning, speeds, CAM profiles, and other operating characteristics. Servo-based multicolor screen-printing machines have a rotary indexing table and individual servomotors for each printhead, each screen, and each fixture. A motion controller synchronizes and controls all print movements.
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