A precision double act

: Injection molding and concurrently decorating plastic parts in multi-cavity molds has been possible for some time using the IMD (In-Mold Decoration) process, but was applicable only to the processing of continuous designs or the manufacture of small, flat components. Complex shaped or larger sized plastic parts requiring an entire IMD foil web width to decorate could only be provided with single image designs in a single cavity. The coating specialist Leonhard Kurz is releasing a patent-pending IMD foil feeding unit that can be used for single-image decoration of these kinds of components in a twin-cavity mold. The IMD SI DUO device, which is integrated into the injection molding machine, controls the feeding of two independently positionable foil webs in a double or multi-cavity mold. It allows two different IMD foil designs to be used, and single-image or continuous designs to be combined arbitrarily; furthermore, the cavities can have identical, mirrored or different geometries. High precision foil positioning is ensured in every case, even with different feed distances for the two foil tracks or with dissimilar plastic components.

Sensor detection of foil registration marks

The precise alignment of the single-image designs is achieved by means of sensors that read the registration marks on the IMD foils. Mounted on the outer sides of each of the two foil tracks are a pair of sensor blocks for the X and Y directions that enable a positioning accuracy of a few hundredths of a millimeter in both directions. For longer components, an additional sensor can be installed to ensure precise positioning in the Y direction.    

Demand for single images increasing

“The IMD SI DUO is our response to new market requirements,” explains Helmut Högl, Sales Engineer Special Application at Kurz. “Multi-cavity injection molding is an increasingly popular productivity booster. And the demand for positioned designs is growing rapidly. Not only single images, but also tactile surfaces, human machine interface and backlighting solutions require the designs to be transferred with a well-defined, very tight tolerance. The IMD SI DUO enables plastic components to be decorated with high efficiency and with extremely precise positioning of the design. With this foil feeding unit we are making the IMD process even more attractive and economical.”

Flexible integration into the production process

The IMD SI DUO is equipped with a programmable logic controller and servo control module, touch panel, and memory function for repeat jobs. The parameter sets of 50 jobs can be stored and then recalled in a flash. The compact device can be adapted to suit the structural and technical requirements of existing injection molding machines or constructed to precisely fit into new machines. If required, the device can be reconfigured from dual to single cavity decoration by centrally arranging one of the foil tracks. The movable control cabinet and the operating panel can be flexibly positioned to suit the production workflow.

The new foil feeding unit can be seen in action for the first time at the KraussMaffei Competence Forum in Munich from 6 – 7 June 2018. Ten-inch HMI displays will be injection molded and decorated with single images in a twin-cavity mold on a KraussMaffei PX 320-2000 injection molding machine.