Attention Points Prior to Extruding Step
The twin-screw extruder machinery has more advantages for producing extruded small aquafeed pellets. Its adjusting range is wider than the single-screw extruder, and also has better material adaptability. However, the single-screw extruder can also produce good quality small pellets if under good control.
Selection and installation of the cutter
Whether the selection as well as installation of the extruder cutter are reasonable or not is decisive to the appearance of the extrudates. It is recommended to adopt 0.3 mm thick soft knives with good elasticity for cutting small pellets. When installing the knives, each of them should be tightly against the die plate and a little bit curved.
It is suggested to adopt a cutting device which the clearance between the cutting blade and die plate is adjustable during production operation. Since the blade will be worn after being used for a period of time, which will leave a small prick on the pellet edge, influencing the trimness as well as the appearance of the pellet. With an adjustable cutting device, the clearance can be adjusted during operation without stopping, ensuring the extruder to work stably for a long time.
Take the single-screw extruder (power of main motor: 160KW, screw diameter: 165mm) as an example, when producing small pellets with a Ø1.0 mm-hole die plate, a cutting device with ten or twelve knives is usually used, and its rotating speed is about 1200～1400 rpm. If there are impurities blocking the die holes, the rotating speed of the cutter must exceed 1500 rpm so as to ensure the uniformity of pellets. So, as for a Grade 4 motor, the upper limit of frequency of an inverter must be over 50HZ.
Extrusion system cleaning
If the feed machinery has been made a halt for more than 8 hours, it is necessary to clean the whole extrusion system thoroughly, including the anti-bridging feeding bin, the feeding auger, the conditioner and the principle machine of extruder.
When cleaning the anti-bridging feeding bin and the feeding auger, it is necessary to empty the material in them, after that, blow compressed air into them for completely cleaning. Do not use tools like besom or brush for cleaning, because the fibrous components of such tools are possible to fall down and bring in more impurities.
When cleaning the conditioner, if the residues on the inner wall of the barrel and on the paddles are dry, use a scraper to remove them, and then flush them with compressed air for complete cleaning. If the residues are relatively wet, only the dry residue on the surface of cylinder's inner wall needs to be scraped and removed out of the conditioner.
Selection and installation of the cutter
Whether the selection as well as installation of the extruder cutter are reasonable or not is decisive to the appearance of the extrudates. It is recommended to adopt 0.3 mm thick soft knives with good elasticity for cutting small pellets. When installing the knives, each of them should be tightly against the die plate and a little bit curved.
It is suggested to adopt a cutting device which the clearance between the cutting blade and die plate is adjustable during production operation. Since the blade will be worn after being used for a period of time, which will leave a small prick on the pellet edge, influencing the trimness as well as the appearance of the pellet. With an adjustable cutting device, the clearance can be adjusted during operation without stopping, ensuring the extruder to work stably for a long time.
Take the single-screw extruder (power of main motor: 160KW, screw diameter: 165mm) as an example, when producing small pellets with a Ø1.0 mm-hole die plate, a cutting device with ten or twelve knives is usually used, and its rotating speed is about 1200～1400 rpm. If there are impurities blocking the die holes, the rotating speed of the cutter must exceed 1500 rpm so as to ensure the uniformity of pellets. So, as for a Grade 4 motor, the upper limit of frequency of an inverter must be over 50HZ.
Extrusion system cleaning
If the feed machinery has been made a halt for more than 8 hours, it is necessary to clean the whole extrusion system thoroughly, including the anti-bridging feeding bin, the feeding auger, the conditioner and the principle machine of extruder.
When cleaning the anti-bridging feeding bin and the feeding auger, it is necessary to empty the material in them, after that, blow compressed air into them for completely cleaning. Do not use tools like besom or brush for cleaning, because the fibrous components of such tools are possible to fall down and bring in more impurities.
When cleaning the conditioner, if the residues on the inner wall of the barrel and on the paddles are dry, use a scraper to remove them, and then flush them with compressed air for complete cleaning. If the residues are relatively wet, only the dry residue on the surface of cylinder's inner wall needs to be scraped and removed out of the conditioner.
muyangsales - 13. Mär, 08:00
