The extrusion molding process is the molding processing method in the field of polymer processing with the largest variety, the most change, the high productivity, the adaptability, the wide application, and the largest proportion of the output. Extrusion molding is to melt the melt (or viscous fluid) of the polymer through a certain shape of the die under the extrusion of the extruder screw, and the product is a continuous profile having a constant cross-sectional shape. The extrusion process is suitable for all polymer materials. Almost all molded thermoplastics, thermoset plastics can also be used, but only a few phenolic thermosets and the like. Plastic extruded products include pipes, plates, bars, sheets, films, monofilaments, various profiles, and composites of plastics and other materials.
About 50% of thermoplastic products are currently extruded. In addition, the extrusion process is also commonly used in the coloring, mixing, plasticizing, granulating and blending modification of plastics, etc., based on extrusion molding, combined with inflation, stretching and other techniques, and developed into extrusion Blow molding and extrusion tenter forming to manufacture hollow blow molding and biaxially stretched films. It can be seen that extrusion molding is the most important method in polymer molding. Affecting the amount of plastic extrusion, it is the impact of making money! Jiuzhi Plastics Network summarizes 18 factors that affect the amount of plastic extrusion? Counting you a few:
(1) Influence of force—The amount of extrusion increases linearly with a decrease in the head pressure.
1 For an extruder with a deep groove and a short screw, the extrusion pressure drops sharply with an increase in the random head pressure.
2 Increase the temperature of the die, and the extrusion amount is slowed down by the pressure of the head.
When the 3 die resistance is high (the effective load area is small), the extrusion amount is more affected by the head pressure.
4 When the screw speed is high, the extrusion amount is high, but the increase in the head pressure is proportional to the decrease in the extrusion amount.
5 The larger the aspect ratio of the screw, the smaller the extrusion volume is affected by the pressure of the head.
6 Uncooled screw, the amount of extrusion is much more affected by the head pressure than the cooled screw.
7 The larger the gap between the screw and the barrel, the larger the proportion of the extrusion head random pressure increase and decrease.
(2) Effect of screw speed - The amount of extrusion increases with the increase of screw speed, but it is not linear.
1 With the increase of the screw speed, the increase of the extrusion amount is related to the material. HDPE>LDPE>PP.
2 The extrusion amount of the low-viscosity molten material is more affected by the screw rotation speed.
3 At high melting temperatures, the amount of extrusion increases as the screw speed increases. However, at low melting temperatures, the increase is minimal.
4 The amount of uncooled screw extrusion is slightly more affected by the screw speed than the cooled screw.
When the die resistance is low, the extrusion amount increases as the screw speed increases; on the contrary, the increase ratio is small.
(3) The amount of extrusion increases rapidly as the melt index of the material increases.
(4) The amount of extrusion increases as the length of the homogenization section increases.
(5) When the head pressure is low, the extrusion amount increases as the depth of the homogenization section becomes deeper; however, if the head pressure is high, the extrusion amount decreases as the depth of the homogenization section becomes deeper.
(6) The amount of extrusion decreases as the gap between the screw and the barrel increases. However, when the gap is larger than 1 mm, the amount of extrusion is remarkably reduced.
(7) The amount of extrusion decreases as the temperature of the feed section increases.
(8) As the melting temperature increases, there is no change in the amount of extrusion at the beginning. When the temperature continues to increase to a certain extent, the viscosity of the material decreases and the amount of extrusion decreases rapidly.
(9) When the temperature of the barrel is increased to a certain limit, the amount of extrusion is also drastically reduced due to the rapid decrease of the viscosity of the material.
(10) The amount of extrusion decreases as the amount of volatiles in the material increases.
(11) The screw temperature is increased and the amount of extrusion is drastically reduced.
(12) As the depth of the groove deepens, the amount of extrusion increases rapidly at the beginning, and when a certain limit is reached, the amount of extrusion decreases sharply. This is because the degree of plasticization of the material in the screw is deteriorated after the depth of the groove is increased.
(13) The amount of extrusion increases proportionally with an increase in the area of ​​the die-forming hole.
(14) The amount of extrusion decreases proportionally with the increase in the length of the advection portion of the die.
(15) For materials with different melt flow rates, the extrusion amount cannot be compared with the screw speed.
(16) The amount of extrusion is not proportional to the screw speed.
(17) Even the same type of extruder (same screw structure, the same temperature setting of each section), due to the adapter length, head area, filter resistance, screw cooling, material preheating temperature, and extrusion The slight difference between the gap between the screw and the barrel of the machine itself, and the amount of extrusion when the same material is extruded is not the same.
(18) For fixed extruders, the extrusion amount will vary depending on the melt pressure, screw temperature, and material stability at different times.
Inks Thickener,Organoclay Inks Thickener,Water Based Inks Thickener,Waterborne Inks Thickener
CHANGXING GUANGDA NEW MATERIALS CO.,LTD. , https://www.gdbentonite.com