The screw of the twin-screw extruder is a modular combination. The combination of the entire screw should be selected according to the specific formulation, material characteristics, mixing requirements, and operating conditions.
The following example illustrates how to make a screw (barrel) component combination for different usage requirements.
First, make sure that the full length of the screw consists of several segments. Several sections can be divided by feeding port and exhaust port. If there is only one feed port and no second feed port or exhaust port, it can be regarded as a section. If there are two feed ports or one exhaust port and one feed port, it is regarded as two segments, and so on. How many paragraphs to use depends on the requirements of the mixing process.
Example 1: When a solid filler is added to a resin and subjected to filling modification without venting, a feed port is generally required.
In this case, the combination of the screw and the barrel can be regarded as a combination. However, there are exceptions. If the packing is seriously worn on the barrel, it is also conceivable to use two feeding ports. The first feeding port is added with resin, and the second feeding port is added with filler. That is, when the resin is melted, the filler is added, so that the melt is melted. The solid filler can be wet-coated so that it does not directly contact the screw and the barrel, thereby reducing the wear of the latter. If the amount of filler added is large and it is difficult to completely add it from one feed port, it is also possible to consider the use of a second feed port or even a side feed port.
Example 2: Two resins with different viscosities were blended to make a plastic alloy.
You need to know the two group allocation ratios. If the low-viscosity material accounts for a small percentage, a feed port can be used, that is, a section is used; if the percentage of the two components is nearly equal, two feed ports can be used to add a high-viscosity material to the first feed port, which is close to A second feed port is provided at the melt to add the low viscosity material at a higher rate. If the proportion of low-viscosity materials is high, even three feed ports can be used. This is considered. If a higher proportion of low-viscosity materials are added from the first feed port together with the high-viscosity material, the former is like a lubricant, which prevents the shearing element from inputting energy into the high-viscosity material so that it cannot be melted. The above method is a specific application of the principle of equal viscosity which is often followed in the production of blends.
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