Vertical Form, Fill, and Seal
Description
Vertical Form, Fill and Seal (VFFS) machines are used in the consumer products industry for a wide variety of packaging applications ranging from high speed candy packaging to low speed coffee packaging. The machine takes raw material, typically dry goods such as cereals or snack foods, and places the product into formed pouches.
The machine starts with film from a roll, which then is formed into a tube. Some machines use a servo axis on the roll of film to maintain tension in the process, such that the exact amount of film material can be used in the process with minimal waste. The feed servo axis will feed the formed film tube the correct length based on the required recipe provided by the operator. If the film is pre-printed, a registration sensor is added to the system to correct the film position in order to maintain the correct print position relative to the end of the pouch. As the feed servo axis pulls down the film, the goods to be packaged are gravity fed into the tube, often by a precision scale, which ensures that the proper amount of goods is placed in the pouch in a consistent manner. Many high-speed applications use multiple servo axes on the feed system simply to ensure that the material is being fed equally on both sides of the forming tube. The crimp servo axis seals the bottom of the tube; the tube is filled and indexed. The crimp servo axis, then seals and cuts the tube, with the product placed between the crimps, to form a pouch.
Solution
ControlLogix with embedded Motion is the control of choice for the VFFS. A typical configuration would include using a 1756-M08SE SERCOS InterfaceTM Motion Module that
links with fiber optic cable to the Kinetix 6000 Servo Drive, one axis on the film roll, one axis (or two, depending on design) on the feed servo axis and one on the crimp servo axis. MP-Series Low Inertia Motors have been chosen for all axes because of the high acceleration and deceleration of machine mechanics, as well as their compact size. Machine operators can use PanelView connected to the ControlLogix platform using EtherNet in order to change recipe information and monitor actual machine characteristics. RSLogix 5000 Programming Software provides flexibility in setup of the control hardware, as well as programming and diagnostics. Through the use of RSLogix 5000 all motor and drive parameters are defined as part of the motion axis configuration and require no secondary software package for machine or drive setup. The ControlLogix controller automatically configures the drives over the SERCOS interface at power-up. This allows for drives to be powered-up right out of the box with little configuration by the user. Programming is simplified as well with the use of virtual axes that provide master coordination for the physical feed servos and crimp servo, as well as fast outputs. Complex motion profiles are simplified with the use of dynamic Position Cam capabilities provided through the use of Motion Cam Calculate Profile (MCCP) and Motion Axis Position Cam (MAPC) ladder instructions, which allow for on-the-fly profile changes.
