Nanjing Extruder Manufacturers Tell You Not To Panic When The Extruder Has Vacuum Material (Part 1)

The Nanjing extruder manufacturer tells you not to panic when the extruder is in a vacuum. During the extrusion process, the gas needs to be discharged from the melt. If these gases cannot be discharged, defects such as pores, air bubbles and surface dullness may appear on the surface or inside of the product, which seriously affect the physical, mechanical, chemical and electrical properties of the product. 1~2 exhaust ports are set between the feeding port and the machine head, which can remove the moisture and other volatile substances in the melt extrusion material. However, there are often some problems with the opening of the barrel. The most common problem is the material from the exhaust port. A small amount of material will affect the discharge of volatiles and affect the quality of the product; a large amount of material will block the exhaust port and even cause shutdown.

Nanjing extruder manufacturers tell you that there are generally two reasons for the extruder to leak. One is that the screw design is unreasonable, which leads to the backflow of the material at the exhaust port; the other is that the design of the exhaust port is unreasonable, and the molten material hangs when passing through the exhaust port. Find out the reason First, check whether the material in the screw is backflowing from the exhaust port. In most vented extruders, you can see the melt rotating forward in the screw. In general, the screw groove is not more than 50% full of material. If it exceeds, it will not only affect the exhaust effect, but also cause material discharge from the exhaust port; when it is less than 50%, the screw can work normally. Bubbling may be caused by improper design of the exhaust port or diverter element.

Nanjing extruder manufacturers tell you the factors that affect the extruder and the solutions.

1. Screw factor

The extruder exhaust screw adopts multi-stage design. The advantage of this design is that there is normal pressure at the exhaust port, and the material will not flow out. A vent extruder requires 2 screws, and 2 vents require 3 three screws. Each stage has an atmospheric pressure section, a compression section and a metering section. The first stage is the atmospheric pressure feeding section, and the second stage is the atmospheric pressure exhaust section, that is, the location of the exhaust port.

There are two main problems in the design of the screw of the vent extruder: one is that when it reaches the vent section, the material must be completely melted to discharge volatile substances; The screw groove at the beginning of the second stage is not filled, and the exhaust port is kept at normal pressure. When the feeding amount of the first-stage screw is larger than that of the second-stage screw, the melt in the extruder will flow backwards. To solve this problem, we have to reduce the feed volume of the first stage or increase the feed volume of the second stage.

Today we will start here, and there are a few more reasons, please see the next article.