How to choose the screw of film blowing machine?
1. Different raw materials require the use of barrel screws with different structures.
2. The production of different products requires the use of different barrel screws.
3. The same raw material, but the quality of the raw material changes, the requirements for the barrel screw will also be different.
The following are references:
A. Output The so-called output refers to the output or extrusion volume of a given head under the premise of ensuring the quality of plasticization. As mentioned earlier, output is generally expressed in kg / hour or kg / rev. A good screw should have a high plasticizing ability. (Production capacity) It should be noted that low-temperature extrusion is a current development trend, which can improve the quality of extruded products (such as reducing internal stress, etc.), prevent overheating decomposition of heat-sensitive materials, reduce energy consumption, and reduce the cooling system of the main and auxiliary machines. Burden and increase productivity.
B.Plasticizing quality A screw must first be able to produce products that meet the quality requirements.
The so-called compliance with quality requirements means that the products produced should meet the requirements of the following aspects:
1. Various performances that meet the requirements. Have physical, chemical, mechanical, and electrical properties in accordance with regulations;
2. It has an apparent quality that meets the requirements. If it can meet the user's requirements for bubbles, crystal points, uniformity of dyeing and dispersion, etc.
3. The plasticizing quality of the screw is in accordance with the requirements: 1) Whether the melt temperature extruded by the screw is uniform, and the axial fluctuation and radial temperature difference are large. 2) Is there a minimum melt temperature that can be formed. 3) Whether there is pressure fluctuation in the extruded melt. Whether the dispersion of dyeing and other additives is uniform.
C. Unit consumption Unit consumption refers to the energy consumed for each kilogram of plastic (rubber) extruded, generally expressed as N. Where N is the power (kW) and Q is the output (kg / h). The larger the value, the more energy is needed to plasticize the same weight of plastic (rubber), which means that the more heating power is consumed, the more the mechanical work done by the motor enters the material through shear and friction heat many. vice versa. On the premise of ensuring the quality of plasticization, the unit consumption of a good screw should be as low as possible.
D. Adaptability The so-called screw adaptability refers to the adaptability of the screw to processing different plastics, matching different heads and different products. Generally speaking, the stronger the adaptability, the lower the plasticizing efficiency. Therefore, we always hope that a good screw should have both adaptability and high plasticizing efficiency.
E.Difficulty in manufacturing A good screw must also be easy to process and manufacture with low cost.