Fluent
Contact: Sales Manager
10 Cavendish Court
Centerra Park
Lebanon,, New Hampshire 03766
U.S.
Phone: 800-445-4454 (603)
Fax: (603) 643-3967
Screw Design Single Screw Extruder Twin Screw Extruder The Challenges Understanding the flow of material around rotating single screws, twin screws or moving impellers is critical. Many defects of the final product are due to a low mixing quality while the pellets are flowing around a single screw; the pressure built by a given screw rotating at a specified rpm can be too short considering the required pressured drop for a new die that just has been cut; while mixing color or foaming additives with a plastic melt through a twin screw extruder, a good quality mixing must reach an additive dispersion as uniform as possible in order to avoid regions of different color or lower foaming intensity. For batch mixers as well, the quality of the mixing created by the rotating impeller is critical to the quality of the final product. See animation In addition, the requested power to apply on the rotating impeller or screw will depend upon the force and torque applied by the flowing material. Getting an evaluation of the power requirement while designing the whole device allows you to acquire the appropriate material. Furthermore, both the cost and the mixing quality will depend upon the geometry of the barrel and the moving impellers or screws, the flowing material and the operating conditions. All these parameters can be modified on the computer in order to select the best operating window. See animation Single Screws Flow pattern, temperature field through the flowing material, pressure increase along the screw, residence time, local shear rate, and local stress are typical information that would be very useful to know while designing or acquiring a screw. Using POLYFLOW, you analyze how a new screw would perform in your own device before acquiring it, or you can demonstrate to your customers that the new screw you have designed will perform much better than the old one. Furthermore, you can vary the operating conditions, such as the rotational speed of the screw, and analyze the subsequent effects, such as pressure built or temperature increase due to viscous heating. This allows you to identify the optimal working window depending upon the device and the flowing material without deteriorating the resin. Twin - Multiscrew Devices Understanding and simulating the flow around the twin screw has always been challenging due to the complex geometry in the vicinity of the interscrew region and the large deformations induced by the two (or more) rotating screws. POLYFLOW has implemented a Mesh Superposition Technique that superimposes meshes (for the flowing materials and the screws itself). Also, non-isothermal flows around the twin screw detecting the high temperatures induced by viscous heating, quality of the mixing performed by particles tracking and statistical analysis together with other many other quantities (pressure, velocity, residence time, mixing index, local shear rate, stresses, viscosity) are calculated. They provide you with a wealth of extremely useful information about the flow of material around the screws.
