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 that are configured in the housing , -- a first infeed opening and a second infeed opening which open into the at least two housing bores , -- at least two treatment element shafts that are disposed so as to be rotatingly drivable in the housing bores , - a first metering installation for feeding an undyed plastic material (M) through the first infeed opening into the at least two housing bores , and - a second metering installation for feeding at least one color granulate (G) through the second infeed opening into the at least two housing bores , characterized in that the second metering installation comprises a first metering unit for feeding the color granulate (G), and a second metering unit for feeding a cleaning granulate (R), said metering units 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 (R) by means of the second metering installation is capable of being fed through the second infeed opening into the at least two housing bores . - a multi-shaft screw extruder for providing a plastic melt (S 1 , S 2 ), having -- a housing , -- at least two mutually penetrating housing bores that are configured in the housing , -- a first infeed opening and a second infeed opening which open into the at least two housing bores , -- at least two treatment element shafts that are disposed so as to be rotatingly drivable in the housing bores , -- a housing , -- at least two mutually penetrating housing bores that are configured in the housing , -- a first infeed opening and a second infeed opening which open into the at least two housing bores , -- at least two treatment element shafts that are disposed so as to be rotatingly drivable in the housing bores , - a first metering installation for feeding an undyed plastic material (M) through the first infeed opening into the at least two housing bores , and - a second metering installation for feeding at least one color granulate (G) through the second infeed opening into the at least two housing bores , characterized in that the second metering installation comprises a first metering unit for feeding the color granulate (G), and a second metering unit for feeding a cleaning granulate (R), said metering units 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 (R) by means of the second metering installation is capable of being fed through the second infeed opening into the at least two housing bores . <EOS>