Operation and Maintenance of Twin-screw Extruder

Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.

Today, we prepared some guidance on operation and maintenace of twin-screw extruder as follows for you reference:

1. Operation of counter rotating twin-screw extruder

1） Preparation and inspection before startup

A．Do not mistake the position of the two screws when loading the screws before starting up, otherwise there will be problems: after starting up and adding materials, the materials will accumulate in the feeding port; if the screw head is not conveyed forward, the screw head will be on the machine head and the current will increase. If this happens, stop the machine immediately, remove the machine head, and reinstall the screw in the correct position.

B.  Before starting up, check whether the wiring of each part of the machine is correct, whether the thermocouple is inserted in the correct position, and whether the temperature control instrument is sensitive. Whether the cooling system of the barrel and screw is normal and unblocked; whether the driving system is normal, whether the lubricating oil level is normal, and whether the oil circuit is unblocked. Whether the metering feeding system is normal and the exhaust system is normal. Whether the connecting bolts of the machine head are tightened, and whether the mechanical, electrical system and waterway of each auxiliary machine are normal.

C.  Before starting up, the part of the extruder that needs to be heated should be heated, and the bottom of the feeding hopper and the screw cooling part shall be cooled by cooling medium. When the set temperature is reached, it shall be kept warm for 10min to make the screw and barrel "hot through".

2）Precautions for startup and shutdown

A． If the material is added, it must be metered, otherwise it is easy to cause overload; When starting up, add a small amount of materials first, keep the feeding balance, and pay close attention to the pointer of ammeter (torque meter). The rotation speed of the main screw should also run at a low speed. After extruding the material in the die and introducing the traction equipment, slowly increase the screw belt, and then increase the feeding amount until it reaches the set value.

B．Stop feeding the feeding device before shutdown, run the main engine screw at low speed, discharge the materials in the screw, and pull out the screw when there is no more material discharged from the standby head. Clean the screw, head and barrel while hot, and then assemble and reset. If special cleaning material is used for the next startup, it is not necessary to pull out the screw for cleaning. The inner hole of the barrel and the head shall also be cleaned. If there is no hurry to reassemble the table, the screw elements shall be coated with e engine oil for protection and standby to prevent rust. When cleaning the head or screw elements, copper knife, copper brush, paraffin wax and gauze shall be used. Steel knife and steel file shall not be used to avoid damaging the working surface.

2.  Maintenance

The twin-screw extruder shall be maintained regularly according to the instructions attached to the factory.

Routine maintenance is also very important. For example, it is not allowed to run empty, so as to avoid the wear of screw and barrel; If the operation is abnormal, it shall be checked and repaired immediately; Strictly prevent metal or other sundries from falling into the hopper. If there is a metal detector, the materials shall be screened and then added into the hopper, which is safer and more reliable. If the machine head is equipped with a pressure sensor, pay more attention to its assembly, disassembly and protection. Do not use hard objects to beat or scrape the accumulated material on the diaphragm of the sensing part, and wear a special protective cover when not in use.

If you need more information, Ningbo Fangli Technology Co., Ltd. welcomes you to contact for a detailed inquiry, we will provide you with professional technical guidance or equipment procurement suggestions.

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