The smoothing device for plastic films comprises plastic-melt-producing means (1, 5), an adjustable slit die (10) and a roller smoothing unit (16) having cooled smoothing rollers (11, 12), which form an adjustable smoothing gap (13) between each other. Optionally, further rollers (15) are arranged downstream. A thickness gauge (23) measures the thickness of the plastic-film web (22). A controller (30) for controlling the thickness of the plastic-film web (22) may set a setpoint thickness (SD) of the plastic-film web (22) and the volumetric flow rate (SS) of the plastic melt or the line speed (LS). The controller (30) captures the current torques and rotational speeds of the rollers (11, 12, 15) and the current thickness (FD, FD1-FDn) of the plastic-film web (22).

The controller (30) sends setpoint rotational speed signals (C0S, C2S-CnS, CAS) calculated from the captured torques of the rollers (11, 12, 15) to the drives of the rollers and a smoothing-gap setpoint distance signal (GW) for adjusting the smoothing gap (13), and furthermore—in the case of a specified line speed (LS)—setpoint plastic-melt volumetric flow rate signals (SS) to the plastic-melt-producing means, or—in the case of a specified plastic-melt volumetric flow rate (SS)—setpoint line speed signals (LS) to the drives of the rollers (12).

The invention relates to various aspects in the production of extrusion products. The properties of extruded articles are dependent significantly, in addition to their formulation, also on the setting variables and in particular on the thus resulting process variables. The setting variables and in particular the process variables thus represent a state of the extrusion process characterized as fingerprint. The thus claimed invention takes into account these facts and supports the operator of a production plant to detect earlier changes in quality and to systematically counteract a deterioration in the quality.

The invention relates to a method for the indirect determination of a specific formulation with an extrusion process in an extrusion device (10) comprising the following steps: determination of measurement data of at least one processing parameter of the extrusion process of the extrusion device (10), comparing the determined measurement data with saved data saved in relation to the specific formulation of the same processing parameter, determination of the deviation of the measurement data from the saved data of the same processing parameters and comparing of the deviation with a predefined deviation threshold.

A system and a method for controlling an extrusion line of mixed plastics, wherein a temperature of one or more heaters of the extrusion line is measured by one or more first sensors; a temperature and pressure of an extruder head is measured by one or more pairs of second sensors; a coolant temperature of a set of dies is measured by one or more third sensors; an amperage of an extruder motor is measured by an ammeter; a pulling speed of a pulling unit is measured by a tester; and wherein a computing device configured to receive the measurement data from the one or more first sensors, from the one or more pairs of the second sensors, from the one or more third sensors, from the ammeter, from the tester.