3D Blow Molding
3D blow molding technology provides new methods and ideas for the design and production of personalized three-dimensional products, which can produce three-dimensional products with complex shapes and diverse structures, while also having good dimensional stability and lightweight characteristics.
Blow Moulding Technologies
Modern blow moulding technologies are developing at a very fast pace and are one of the main plastic molding methods, providing high-precision production services for seamless containers. The main function of this technology is to produce lightweight hollow containers with uniform wall thickness and stable size. The process of hollow blow molding is very simple. The molten billet is placed into the mold, compressed air is used to blow and expand the billet, and maintained for a certain period to make it tightly adhere to the inner wall of the mold. Finally, it is cooled and formed into a seamless hollow product. Due to the various advantages of plastic blow molding technology, it is widely used in various fields of life, such as beverage bottles and other containers in the household field, as well as in various fields such as medical, chemical, and agriculture.
Classification of Blow Moulding Technologies
Blow moulding technologies are key methods for manufacturing plastic products, which are closely related to both ordinary bottles and containers with special purposes. But different products also need to choose different blow molding techniques for manufacturing. Common blow molding techniques include extrusion blow molding, injection blow molding, stretch blow molding, multi-layer blow molding, and 3D blow molding.
Extrusion Blow Molding:
Extrusion blow molding is currently the most widely used molding method, mainly producing barrels of various shapes and types. Extrusion blow molding mainly involves plasticizing plastic and extruding the blank, then placing it in the mold, compressing air to blow and expand the blank, and cooling it to obtain the formed part. One prominent advantage of extrusion blow molding is that it can achieve continuous production and high production efficiency; The selection of raw materials is also quite extensive, such as liquid silicone rubber, plastic, fibers, etc; And its equipment is simple, the utilization efficiency of the machine is high, and installation and debugging are also relatively convenient.
Injection Blow Molding:
Injection blow molding is a method of first injecting molten plastic into an injection mold to make a preform, then transferring it to the blow molding mold while it is hot, and then blowing and expanding it to produce a product. Injection-blown products generally do not require trimming, resulting in less waste and reducing manual operation steps. The molding speed of injection-blown molding is faster, and the material shrinkage rate is generally smaller, so the size of the product can be accurately controlled. However, if it is a small-scale production, the injection blow molding process is not suitable.
Stretch Blow Molding:
Stretch blow molding is a method of injecting or extruding a blank into a mold, then stretching it with a stretching rod, and then blowing it with air for expansion. Stretch blow molding can effectively improve the properties of plastics, resulting in a significant increase in transparency, impact resistance, and hardness. Stretch blow molding technology also simplifies the maintenance and upkeep of molds, greatly improving production efficiency.
Multi-Layer Blow Molding:
Multi-layer blow molding is a method of producing hollow products by extruding or injecting two or more layers of preforms, followed by blow molding. Multi-layer blow molding is mainly capable of producing products without burrs and cutting marks, producing products with better quality and higher strength based on the original single layer, and can effectively extend the service life of the product.
3D Blow Molding:
The main process of 3D blow molding is to pre-blow expand the extruded blank, tightly adhere to the mold wall, and then rotate the mold or extrusion head in 2 or 3 axes. When the three-dimensional blank fills the mold cavity, the other side of the mold closes, separates the subsequent blank, and then blow expands the entire blank to complete the molding. The main advantages of 3D blow molding are the absence of burrs, reduced workload, and flexible mold design.
The Advantages and Disadvantages of Blow Moulding Technologies
Blow moulding technologies are an essential component of the plastic product industry, and the quality of the technology can directly affect the quality of blow-molded products. With the development and growth of the blow molding industry, its manufacturing technology is constantly being updated and iterated, advancing towards high quality and environmental protection. The following are the main advantages and disadvantages of blow molding technology:
Advantage
- Simple Process: The blow molding process is relatively simple compared to other plastic molding processes, requiring fewer machines, and the raw materials in the production process are also relatively diverse.
- Low Risk: In the production process of blow molding molds, the product quality is more stable, and the risk of warping and deformation is relatively easy to control, making the product reliable.
- Long Product Life: When processing, there are many types of plastic materials available, which have certain chemical resistance and can be adapted to various processing methods.
- High Production Efficiency: The blow molding process can be highly automated, achieving continuous production, and the speed of putting blow molding molds into production is also fast, with low difficulty in mold testing.
- Multiple Types of Products, Relatively Flexible: Blow molding processing produces a wide variety of products, which are applied to various industries and can flexibly adapt to various needs.
- Environmental Protection: Blow molded products are clean, have high transparency, and generate low energy consumption during the production process. Compared to other technologies, blow moulding technologies are more environmentally friendly and easy to recycle and regenerate.
Defect
- Uneven Wall Thickness: During the blow molding production process, the flow and cooling speed of plastic in the mold may be inconsistent, which can easily lead to inconsistent wall thickness of plastic and affect the aesthetics of the formed parts.
- High Requirements for Raw Materials: In the blow molding process, suitable raw materials must be selected, and their fluidity must be consistent with the cooling rate in the production process to prevent defects in the formed parts.
- High Requirements for Molds: During the blow molding process, due to the variety of products and the high demand for molds, various types of cavities need to be designed.
- Low Precision: Compared to injection molding, blow-molded products have lower precision, so they are not suitable for products with higher dimensional accuracy requirements.
- Product Fflashes too Thick: During the blow molding process, there may be problems such as insufficient locking force or shallow clamping mouth, which can lead to excessive or thick flashes. After production, manual trimming is required.
- Blurred Product Surface Graphics and Text: If problems such as poor exhaust occur during the blow molding process, it can lead to poor plasticization of the product, making it unable to fully contact the mold surface, resulting in blurry graphics and text on the product surface.
Key Technical Points of Blow Moulding
Blow moulding technologies are not just about producing molds, the production parameters are also very important. Only by adjusting the appropriate production parameters can many technical problems be easily solved.
Shrinkage Rate
Due to the characteristics of thermal expansion and contraction, plastic parts may experience a certain degree of shrinkage during the molding process, reducing dimensional accuracy. The degree of shrinkage is determined by the shrinkage rate, reflecting the degree of cooling reduction of the plastic after removal. The factors that affect the shrinkage rate include the variety of plastic, the molding process and temperature, injection pressure and direction, etc.
Demolding Slope
The setting of the demolding slope is mainly to prevent difficulties in demolding plastic parts and the appearance of scratches on the surface of plastic parts during demolding. The setting of the demolding angle mainly depends on the shrinkage rate and wall thickness of the material. For example, when producing products with a high plastic shrinkage rate and thick plastic parts, a larger demolding angle can be selected; In addition, complex products also require a large demolding angle.
Arcs, Fillets, and Chamfers
The corners and other positions of the plastic parts should be designed as circular arcs as much as possible, otherwise designing them as sharp corners will cause the material to become thinner and the edges to be easily broken. The rounded edges are smooth without any sharp edges, which can reduce stress concentration and provide a certain degree of protection to the plastic parts. Chamfering has a certain slope, and the two sharp corners are obtuse angles, which can also effectively protect the plastic part. The combination of the two can bring good strength and aesthetics to plastic parts.
Inflation Ratio
The inflation ratio is one of the important parameters in thin film blow molding production. The expansion ratio refers to the degree of stretching of the film. Increasing the expansion ratio can improve the strength of the film, but if it continues to increase after reaching the optimal performance, it will lead to wrinkles in the film.
Blow Molding Pressure
The pressure of blow moulding technologies can be divided into two aspects, one is blowing expansion, and the other is cooling. Products with smaller volumes and thicker wall thickness are suitable for lower pressures; Products with larger volumes and thinner wall thickness are suitable for higher pressures.
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