Design requirements for plastic extruder screw
Nowadays, in order to save production cost, improve product quality and give full play to the performance of plastic extrusion equipment, the key elements of extrusion process must be mastered.
Each plastic products production and processing enterprises, especially given priority to with color printing plastic extrusion composite packaging film production of custom plastic extrusion supplier, every senior technical management personnel, must want to know your business very well products to raw material properties, processing technology, the performance of the extrusion equipment, product quality control, productivity, lower production costs and some other related factors, however, in the many factors, one thing is most important. Namely; Nine important factors in extrusion process. This is every extrusion compound plastic manufacturers, all levels of technical management personnel must firmly grasp. For this, we through many years of exploration and research, finally in the extrusion process to master some shallow knowledge, cast a brick to attract jade, for your reference.
Fully understand the design requirements of extruder screw
Each extrusion composite film manufacturers, in the use of their own extruder, the first to fully understand the screw all the important correlation. We know that the extruder screw design is very important, even if you buy a new screw, also make sure that the extruder screw design, whether you want to shape, function, material and high-speed operation of the screw. Such as, need to buy a used for the extrusion of PE screw extrusion film, you should know that it's material, heat treatment, and screw the screw thread and must complete some functions, for example, continuous adding resin, uniform melt resin, stable injection liquid homogeneous mixed resin and working cycle, such as amount of material, material bolus geometry, back pressure and screw geometry. You must have a set of data and parameters that display the various functions of the screw used. Because, in today's computer world, simulation technology is easy and should simulate all the screws, unless you can get the relevant data of the same material applicable to the actual situation.
Because the wear of each screw is related to the problem of screw design, a worn screw is not necessarily a bad screw, sometimes the wear is even beneficial to the mixture in the cylinder, or when there is a pressure peak is conducive to increase production, which is beneficial to determine the location and cause of wear. What is needed, however, is proof that wear is causing trouble, which could mean higher melt temperatures for a given input interface.
At the same time, we must grasp the current development of screw design, because the most popular extrusion manufacturers are universal screw, which for each manufacturer in the production of several raw materials, can be universal. But must grasp, understands this kind of universal screw design is one kind of thread compression screw, has a feeding section, a compression section and a metering section, respectively accounts for the thread total length 50%, 25% and 25%. The thread spacing of the screw is equal to its diameter, and the tooth width of the screw is equal to 1/10 of its diameter. Taper processing of compression section is of gradual open type, and the compression ratio can be 2:1 to 3. 1. The calculation method is to divide the thread depth of feeding section by the thread depth of measuring section. Screw thread length, and screw diameter ratio L/D ratio of 16:1 ~ 24:1.
There are no feeding and metering depths in this narrative, without which the compression ratio is meaningless. It is easy to see that the screw is 60mm, 20:1, L/D, GP (universal screw) from the screw with feeding depth range between 6mm and 10mm provided by different extruder manufacturers. These depth values affect the filling and transportation of the material, the amount of plastic present in the screw cavity, the material flow, the shear ratio, and the overall melt quality. Regardless of the exact depth, length, and width of the thread teeth of the screw used, the screw still brings effective value to the industry. The key is the universal screw used in this extruder, and the two elastic characteristics set the direction for its future application. Feature 1 is the function of screw design, which can handle various resins according to various cycles and amount of materials without damaging the properties of polymers. Feature 2 is that the manufacture of universal screw design is the cheapest screw design.
The basic principle of extruding plastic - - the cylinder of each screw rotates and pushes the plastic forward. The screw is actually a ramp, or slope, wound around the central layer. The aim is to increase the pressure in order to overcome greater resistance, which is needed for each extruder. The friction between solid particles on the cylinder wall in the screw rotation before a few turns, their mutual friction, the screw does not move in the axial direction, although it may turn around in the circumference of the rapid rotation, but the axial force on the screw is balanced. The single screw extruder are right hand thread, it has reverse rotation, when seen from behind because they try to spin out the back cylinder, which can exert a feeding tube of plastic melt in the big thrust forward, at the same time, also for an object to a same direction thrust, this power is ultimately fell behind the inlet of the thrust bearing.
That's all for the sharing, thanks for your reading, and we also supply Custom Pvc Plastic Extrusion Profile for sale, if you have any demand for our products, just feel free to contact us.