Wall thickness control of plastic blow molding products

The wall thickness of plastic blow molding products is one of the important factors affecting product quality. If we want to produce high quality plastic blow molding products, the wall thickness control of plastic blow molding products should not be ignored. Today, HUAN MACHINERY is going to share with you the solution to the wall thickness of different blow molding products.

Die mold

Refers to the mouth mold or mandrel position of the extrusion head of the blow molding machine to open grooves, expand the gap of the mouth mold at the corner, so as to change the thickness of the billet, obtain the deformed billet, make up for the uneven wall thickness of the blow molding products caused by the inconsistent blowing ratio, and then obtain the symmetrical wall thickness of the blow molding products.

Axial wall thickness control technology

The effect of the wall thickness control method of plastic products is to promote the extrusion of plastic embryos can form different thickness along the axis according to the different blowing ratio of different blow molding products, so as to ensure that the blow molding products have uniform and stable thickness.

The wall thickness control method is to change the opening volume of the engine by making the mandrel or die move in axial direction according to the preset position, so as to realize the purpose of changing the wall thickness of the billet.

Radial wall thickness control technology

Although the axial wall thickness control method can change the wall thickness distribution in the height direction of plastic blow molding products, but because the horizontal section of the billet extruded is still thick and circular, if the radial blowing ratio of plastic blow molding products is relatively high, the wall thickness control effect is not particularly ideal.

Therefore, radial wall thickness control technology was developed. The technology can make the extrusion billet show non-circular section change at the desired position. Since the development of radial wall thickness program control technology, two typical designs have been roughly formed, one is called flexible ring type, the other is called mouth edge repair form.

Radial wall thickness control technology is an effective method to improve the quality of large plastic hollow blow molding products, and can also reduce the quality of products. Take 200L plastic blow molding water tank as an example, at least 5 to 10 percent of the raw materials can be saved.

The combination of axial wall thickness control and radial wall thickness control can obtain the ideal plastic billet, so as to obtain the plastic blow molding products with more uniform and stable wall thickness.

Blank temperature difference method

Blank temperature difference method

If the proper wall thickness control method can not be taken in the process of blow molding, the deformation of the mold embryo will occur, resulting in uneven wall thickness of blow molding products.

The deformation resistance of billet can be expressed by viscosity, which is related to its temperature. Therefore, in the process of extrusion, it is necessary to cool the part of the billet with large blowing by the cooling equipment, so that the billet has a reasonable temperature gradient. The parts of billet with larger billet blowing have lower temperature, higher viscosity and higher deformation resistance.

In the free blowing stage, the parts with large blowing are difficult to deform, and the deformation amount decreases, while the deformation amount of the parts with small blowing increases. When the parts with a small amount of deformation complete deformation, enter the stage of constrained blowing, blowing more than most continue to deformation, until blowing forming parts, in order to improve the uniformity of wall thickness distribution of plastic blowing products.

As for wall thickness control, HUAN MACHINERY adopts MOOG wall thickness controller and corresponding wall thickness control technology from America, which solves the wall thickness problem of blow molding products more conveniently and simply.

The above is the wall thickness control method of plastic blow molding products brought to you today by HUAN MACHINERY. The wall thickness of blow molding products is only one of the common problems of many hollow blow molding products. As for the solutions to other problems,Common problems and solutions of hollow blow molding products for more detail information.