On the one hand, there are many extruder products on the market with varying quality. On the other hand, users lack relevant professional knowledge and find it difficult to distinguish between them. They do not know how to choose the extruder equipment that suits them. As a professional manufacturer of puffing machines, we are happy to provide our customers with advice on puffing and related issues that everyone is concerned about.

How to distinguish screw extruders

Structurally: According to whether the working part is one shaft or two shafts, it is divided into single-screw extruder and twin-screw extruder; single-screw is divided into left-hand and right-hand, and twin-screw is divided into co-directional flat twin and opposite-direction flat twin. The left-hand single screw or the right-hand single screw basically have the same change in the properties of the material in the barrel, while the shear strength and cleaning ability of the co-directional flat double screw or the counter-rotating flat double screw are significantly different. The most common ones are right-hand single screw and co-rotating flat twin screws.

How it works

According to whether the material is conditioned by steam before entering the barrel (expanding chamber) of the extruder, it is divided into dry extruder and wet extruder. If it is tempered by steam, it is a wet working mode; otherwise, it is a dry method.

The purpose of steam conditioning is to increase the temperature of the material, soften and partially pre-cook the material, and add a certain amount of moisture. For most materials, wet puffing is more efficient than dry puffing. For a simple analysis, only the temperature factor is considered. If the expected maturation temperature of the material is 130°C, the dry puffing screw extrusion part is increased from room temperature (20°C). To reach this value, the temperature needs to be increased by 110°C. If the wet method is used for production, the temperature after conditioning is 80°C, and the material temperature that needs to be raised in the screw extrusion part is 50°C. Therefore, less mechanical energy and more energy are required than the dry method. Can be used to increase production. In addition, due to the softening of the material, the wear on the screw and barrel will also be reduced.

Detailed explanation of dry and wet methods

Many users, including some equipment manufacturers, take it literally and think that adding water is the wet method. From the above brief analysis, we can know that simply adding water cannot be called a wet method. It only supplements part of the water and does not have the effect of increasing the temperature of the material, softening and partially pre-cooking the material.

Due to the different properties of the materials entering the barrel during dry/wet production, the wet material entering the barrel is hot and humid soft material, while the dry method entering the barrel is raw and cold hard material. Therefore, the main shaft system and the extrusion screw are The configuration requirements are also different. Generally speaking, a dry process machine equipped with a steam conditioning system can be used for wet production, and the efficiency will be improved, but it is not as efficient as a dedicated wet process model; the impact of hard materials on the shaft system of a wet process model must be considered during dry production. Dry production can be used for some materials, but the efficiency will be reduced, and it is not applicable to some materials. In other words, dry process machines can produce wet processes, but wet process machines may not necessarily be used dry processes.