Device for producing a dyed and an undyed plastic melt, comprising - a multi-shaft screw extruder for providing a plastic melt (S 1, S 2), having -- a housing, -- at least two mutually penetrating housing bores (7, 8) that are configured in the housing, -- a first infeed opening and a second infeed opening which open into the at least two housing bores (7, 8), -- at least two treatment element shafts (9, 10) that are disposed so as to be rotatingly drivable in the housing bores (7, 8), - a first metering installation for feeding an undyed plastic material through the first infeed opening into the at least two housing bores (7, 8), and - a second metering installation for feeding at least one color granulate through the second infeed opening into the at least two housing bores (7, 8), characterized in that the second metering installation comprises a first metering unit for feeding the color granulate, and a second metering unit for feeding a cleaning granulate, said metering units (19, 20) opening into the second infeed opening, that the second infeed opening in a conveying direction is disposed upstream of the first infeed opening, that the device comprises a control installation for selecting between a first operating mode (B 1) for producing the dyed plastic melt (S 1) and a second operating mode (B 2) for producing the undyed plastic melt (S 2), that the control installation is configured in such a manner that in a cleaning mode (B 3) the cleaning granulate by means of the second metering installation is capable of being fed through the second infeed opening into the at least two housing bores (7, 8). - a multi-shaft screw extruder for providing a plastic melt (S 1, S 2), having -- a housing, -- at least two mutually penetrating housing bores (7, 8) that are configured in the housing, -- a first infeed opening and a second infeed opening which open into the at least two housing bores (7, 8), -- at least two treatment element shafts (9, 10) that are disposed so as to be rotatingly drivable in the housing bores (7, 8), -- a housing, -- at least two mutually penetrating housing bores (7, 8) that are configured in the housing, -- a first infeed opening and a second infeed opening which open into the at least two housing bores (7, 8), -- at least two treatment element shafts (9, 10) that are disposed so as to be rotatingly drivable in the housing bores (7, 8), - a first metering installation for feeding an undyed plastic material through the first infeed opening into the at least two housing bores (7, 8), and - a second metering installation for feeding at least one color granulate through the second infeed opening into the at least two housing bores (7, 8), characterized in that the second metering installation comprises a first metering unit for feeding the color granulate, and a second metering unit for feeding a cleaning granulate, said metering units (19, 20) opening into the second infeed opening, that the second infeed opening in a conveying direction is disposed upstream of the first infeed opening, that the device comprises a control installation for selecting between a first operating mode (B 1) for producing the dyed plastic melt (S 1) and a second operating mode (B 2) for producing the undyed plastic melt (S 2), that the control installation is configured in such a manner that in a cleaning mode (B 3) the cleaning granulate by means of the second metering installation is capable of being fed through the second infeed opening into the at least two housing bores (7, 8).