What are the main factors affecting extrusion blow molding? Hollow blow molding production raw materials, mold size and quality, blowing pressure, blowing mold temperature, blowing speed, blowing ratio, etc.
1. Selection of raw materials
One of the main factors affecting blow molding is the choice of raw materials for production. In blow molding, the production of raw materials is important. To meet the requirements of the products used, the processing properties of the raw materials must meet the requirements of the blow molding process. HDPE resin is generally used, which is beneficial to prevent the parison from sagging, and it is easy to obtain a parison with a uniform wall thickness.
2. The size and quality of the mold
The mold is the main part that determines the shape of the parison size, so the inner wall of the mold is required to be uniform and smooth, and the surface roughness is low, which is conducive to obtaining a parison with a smooth surface.
3. Inflation pressure
In the blow molding process, compressed air usually serves two functions. One is to use the pressure of compressed air to inflate the semi-melted tube blank to the inner wall of the close-fitting aluminum film to form the required shape, and the other is to cool the blow-molded product.
The role of inflation pressure is in the second stage of extrusion blow molding. Parison inflation, inflation pressure is an important factor affecting the wall thickness. The parameters of the inflation pressure include three factors: the size of the inflation pressure, the time of the inflation pressure, and the position of the inflation pressure. These three factors will directly affect the wall thickness and appearance quality of extruded hollow blow molding products.
4. Blow mold temperature
The temperature of the blow mold has a great influence on the quality of the blow-molded products of the blow molding machine, especially the performance quality.
If the temperature of the blow molding mold is too low, the temperature of the parison at the jaw will drop too fast, which will affect the inflation molding of the parison, and will also cause the surface of the blow molding product to appear mottled, rough surface, and poor brightness;
If the temperature of the blow mold is too high, the cooling time will be prolonged and the production efficiency will be reduced. Case.
The temperature of the blow mold has a great influence on the quality of the blow-molded products of the blow molding machine, especially the performance quality. When designing, the temperature of the blow mold should be well controlled, and the temperature distribution should be as uniform as possible, so that the extrusion blow molding product can be cooled evenly during the molding process.
Therefore, the temperature of the blow mold should be well controlled during the design, and the temperature distribution should be as uniform as possible, so that the extrusion blow molding product can be cooled evenly during the molding process.
5. Air blowing speed
In order to shorten the blowing time and obtain a uniform thickness and a good appearance for the blow-molded products, a low airflow speed will be used to inject a large flow of air to ensure that the parison expands evenly and rapidly in the mold cavity and shortens the mold. During the cooling time of the cavity, it is beneficial to improve the performance of the product. The low airflow speed can avoid partial vacuum in the parison, causing the product to sink in.
6. Inflation ratio
The inflation ratio refers to the ratio of the large diameter of the blow molded product to the diameter of the parison. When the size and quality of the parison are constant, the larger the size of the product, the larger the inflation ratio and the thinner the thickness. The inflation ratio should be determined according to the type and nature of the raw materials, and the shape and size of the blow-molded product.
The above are six common main factors that affect extrusion blow molding.
September 12, 2022
July 25, 2022
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