Abstract : This paper introduces the development of an automatic control system for a masterbatch feeder. The system uses a programmable logic controller (PLC) and a frequency converter to achieve automatic control of adding masterbatch during the production of colored filaments in the synthetic fiber industry. Keywords : Programmable logic controller; Frequency converter; Control; Masterbatch; Spinning 1 Nylon Filament Spinning Equipment and Process Our company's nylon branch uses the following high-speed spinning equipment for producing POY nylon filaments: The screw extruder is a product of Sonia (Italy), model M90-FO; the winding equipment is a product of Toray Industries (Japan), model TW-603/6, with 12 positions, and is equipped with 12 spinning metering pumps. The process flow is shown in Figure 1. [align=center] 1. Rotary drum; 2. Storage tank; 3. Screw extruder; 4. Spinning metering pump; 5. Figure 1. Schematic diagram of nylon filament process flow. After the caprolactam chips are dried in a rotary drum, they are fed into a storage tank. The screw extruder rapidly melts the chips and sends the melt into a metering pump. The melt is then formed into fine streams by the spinneret assembly, cooled, and becomes solid fibers, which are then sent to the winding equipment to form POY nylon filaments. Previously, the method for producing colored nylon filaments involved drying masterbatch chips and caprolactam chips together in a rotary drum in a certain proportion, then sending them to a storage tank, and producing colored nylon filaments using the above process. The drawback of this method is that the masterbatch chips color the inner wall of the rotary drum during the drying process. When changing to a different product, workers must enter the drum to clean it, increasing the labor intensity and posing a safety hazard. [b][align=center]For more details, please click: Development of Automatic Control System for Masterbatch Feeder[/align][/b]