Flexo printing machine

Source: CAN Newsletter March 2005

The flexo printing machine of the Italian manufacturer Flexotechnica prints up to twelve colors and is equipped with multi-axis controllers and stepping motors. In connection with the appropriate software, the machine concept reduces unproductive set-up times to a minimum, thus assuring the flexibility of the system in a cost-effective way.
The controller co-ordinates four, eight, ten or twelve ink zones and up to 72 positioning drives.

In flexo printing, raised areas of the printing forms receive the ink from the ink cylinder and transfer it to the surface to be printed. In flexo printing machines with a central cylinder, the material is guided around the impression cylinder. Up to ten printing units are arranged around this cylinder. Each of these printing units consists of an ink chamber, a screen cylinder and a plate cylinder. The image information to be printed is contained on the plate cylinder. The screen cylinder takes the ink from an ink chamber and transfers it to the plate cylinder. This assures that the amount of ink transferred to the plate cylinder is exactly defined. Depending on the print job, the controller of the new machine concept activates individual ink zones and deactivates the ink zones not required for the current job. While the current job is still running, the controller can prepare the deactivated ink zones for the next print job.

The machine concept uses standardized programming systems such as Codesys, standardized communication interfaces such as Ethernet TCP/IP, OPC Client/Server and CANopen. CANopen controls the communication between the motion controller and the drive controller, while the communication blocks according to the CiA 405 interface and device profile for IEC 61131-3 programmable controllers are responsible for IEC integration. The existing operating and diagnosis concept of the machine manufacturer with end user settings via an industrial PC was retained. From the central operating panel, the operator can see all processes and settings and change the settings. This way, the user has a proven, mature and user-friendly human machine interface, which enables the supervision of the printing process. In addition, the operator can prepare the next print job while the current job is still running. In the case of problems, Ethernet communication allows for remote diagnosis of the machine status so competent machine maintenance or at least the preparation of the maintenance can be performed in a time saving way.