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A guide to blow molding process control: key factors and optimization tips

Views: 7     Author: Site Editor     Publish Time: 20-05-2024      Origin: Site

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A guide to blow molding process control: key factors and optimization tips

The blow molding process is an efficient method for manufacturing hollow plastic products and is widely used in packaging, automobiles, medical and other fields. However, to ensure product quality and production efficiency, precise control of key factors in the blow molding process is very important. This article will explore the main influencing factors and control methods in the blow molding process.


During the blow molding process, there are several key factors that affect parison formation and quality.The main factors are parison temperature control, optimization of blowing pressure and speed, adjustment of inflation ratio, mold temperature management, improvement of cooling time and efficiency and reasonable arrangement of molding cycle.


Parison temperature control


Parison is the initial tubular material in the blow molding process, and its temperature is critical to the entire blow molding process. The temperature of Parison directly affects the stability of its shape, the surface finish of the product, the strength of the seams, and the cooling time.


- Effect of temperature on product shape: When the temperature of Parison is too high, its strength will decrease, and the product will easily expand and deform, resulting in uneven wall thickness, especially the longitudinal wall thickness of Parison. At the same time, the cooling time of the material will also be extended, reducing the production efficiency of the blow molding machine.


- Effect of temperature on product performance: Lowering the temperature of Parison can ensure that it has sufficient strength, but too low a temperature will shrink the length of the tube blank and increase the wall thickness, which may lead to an increase in residual stress inside the product and affect the product strength. and appearance quality.


In order to ensure that the product has sufficient surface finish and seam strength without affecting the shape stability of the parison, the temperature of the parisson can be appropriately increased.


Optimization of blowing pressure and speed


Blow pressure and speed are two key parameters in the blow molding process. They jointly determine the degree of fit between Parison and the inner wall of the mold, thereby affecting the appearance and surface quality of the product.


- The role of blowing pressure: Compressed air plays three roles in the blow molding process: to expand the rubbery tubular preform and fit it to the inner wall of the expanded mold cavity; to apply pressure to the expanded Parison to obtain the shape Products with correct and clear surface patterns; promote product cooling.

- The influence of air blowing speed: increasing the amount of air filled into the cavity per unit time, that is, increasing the expansion speed, can shorten the expansion time of Parison, making it easier to obtain products with uniform wall thickness and excellent surface quality. However, if the expansion speed is too fast, the pressure in the air inlet area may be too low, forming a vacuum, causing dents and deformation.


Therefore, controlling the blowing speed to achieve uniform and rapid expansion is an important means to improve product quality.


Adjustment of inflation ratio


The blow up ratio refers to the ratio of the product size to the size of the Parison, that is, the expansion multiple of the Parison. The size of the blowing ratio directly affects the volume of the product and the efficiency of raw material use.


- The impact of the blow-up ratio on product volume: With the same raw material usage, increasing the blow-up ratio of Parison can produce a product with a larger volume. This means that using a larger expansion ratio can save raw materials to a certain extent.

- The impact of the inflation ratio on product performance: As the wall thickness of the product gradually becomes thinner, expansion molding becomes more difficult, the strength and rigidity of the product will also decrease, and the stability of the product shape will become worse.


Therefore, reasonably determining the inflation ratio is an important strategy to ensure product quality and economic benefits.


Mold temperature management


Mold temperature has an important influence on the cooling and solidification process of plastics. The temperature of the mold will directly affect the cooling rate of the plastic in the mold, thereby affecting the molding quality and production efficiency of the product.


- The impact of mold temperature on product molding: If the mold temperature is too low, the cooling rate of the plastic in the mold will be accelerated, resulting in insufficient molding time for the plastic in the mold, affecting the shape and dimensional accuracy of the product.

- The impact of mold temperature on product performance: If the mold temperature is too high, the cooling time of the product may be too long, the production cycle will be extended, and the production efficiency will be reduced.


Therefore, reasonable setting of mold temperature according to the type and physical properties of plastic is the key to ensuring product quality.


Improvement of cooling time and efficiency


Cooling time is an integral part of the blow molding process, which is directly related to the final appearance quality and physical and mechanical properties of the product.


- The importance of cooling time: Uneven or insufficient cooling of blow molded products in the mold will cause product deformation and affect the appearance quality and physical properties of the product.

- Optimization of cooling efficiency: By optimizing cooling methods, such as using cooling channels or internal cooling media, cooling time can be effectively shortened and production efficiency improved.Our jerry can blow molding machine uses secondary cooling to ensure that the bottle mouth and jerrycan body are not deformed, and the products produced are smooth, beautiful and error-free.


At the same time, ensuring sufficient cooling time is also an important measure to avoid product deformation and improve product quality.


Reasonable arrangement of molding cycle


The molding cycle includes a series of steps such as extruding Parison, cutting, mold closing, blow molding, cooling, deflating, mold opening and product removal. Properly arranging the molding cycle can not only ensure product quality but also improve production efficiency.


- Optimization of the molding cycle: By optimizing the operations of each step, the molding cycle can be shortened and production efficiency improved. For example, by increasing the opening and closing speed of the mold and reducing the residence time of the product in the mold, the molding cycle can be effectively shortened.

- The impact of the molding cycle on product quality: An unreasonable molding cycle may lead to product quality defects. Therefore, precise control of the molding cycle is the basis for achieving efficient production.



The control of the blow molding process is a complex process involving multiple interrelated factors. Through precise control of Parison temperature, blowing pressure and speed, blowing ratio, mold temperature, cooling time and molding cycle, the quality of blow molded products can be significantly improved while improving production efficiency. Manufacturers need to continuously optimize these parameters to adapt to changing market demands and improve competitiveness. With the continuous advancement of technology, the use of intelligent and automated control methods will become the future development trend of the blow molding industry.


With the advancement of Industry 4.0 and intelligent manufacturing, the blow molding process in the future will be more intelligent and automated. By integrating advanced sensors, control systems and data analysis technology, real-time monitoring and optimization of the blow molding process can be achieved. This will further improve product quality, reduce production costs and shorten product time to market.


In addition, with the increasing awareness of environmental protection and the demand for sustainable development, future blow molding processes will also pay more attention to environmental protection and efficient use of resources. This includes using recyclable or biodegradable plastic materials, reducing energy consumption and waste generation.


In short, the blow molding process, as an efficient and flexible plastic processing technology, will still have broad room for development in the future. Through continuous technological innovation and optimization, the blow molding process will provide more high-quality plastic products for all walks of life and meet people's growing material and cultural needs.


If you want to know more, HUAN MACHINERY is a good choice.

Mail: huanmachinery@vip.163.com



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