Plastic Blow Molding
The production process of plastic blow molded products is simple and highly automated, generally using continuous production methods, which can achieve efficient mass production and are suitable for large-scale production of plastic products.
Advanced Blow Moulding Technologies
Blow moulding technologies are constantly developing, and more and more manufacturers are proposing improved methods to make blow molding technologies more widely used in high-precision fields such as medical, automotive, aerospace, etc. The products produced by plastic blow molding technologies have high flexibility, and physical and chemical properties, and have been found in every corner of daily life, which further illustrates the importance of this type of technology.
The Advantages and Limitations of Blow moulding Technologies
There are many advantages to blow moulding technologies, but there are also certain limitations, so when choosing a manufacturing method, comprehensive consideration should be given.
1.Advantages
- High Cost-effectiveness: The mold manufacturing of blow moulding technologies is relatively simple compared to injection molding technology, and the cost is relatively low. This advantage is particularly evident when producing large quantities of products.
- Flexibility: Blow moulding technologies produce a wide variety of products, such as bottles, barrels, oil drums, and other hollow containers. Customized services can also be provided according to customer requirements.
- Excellent Chemical Properties: The plastic raw materials used in plastic blow moulding technologies (such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), etc.) have strong corrosion resistance, and the products produced from them can adapt to various environmental conditions.
- High Production Efficiency: The advanced technologies of blow moulding have popularized highly automated production, achieving continuous production. Once the initial mold design and manufacturing are completed, it can be put into use in a very short period.
- Stable Quality: The products produced by blow moulding technologies have stable quality. The heating, forming, and cooling processes of blow molding are relatively simple, making it easy to control the size, wall thickness, and other parameters of the product to ensure consistency.
2.Limitations:
- Long Mold Design and Manufacturing Cycle: The requirements for blow moulding technologies are relatively precise, so molds need to be designed with great caution and undergo trial processing, which requires a considerable amount of time and effort. Especially for blow molding molds of complex-shaped products, multiple designs, and modifications are required.
- Uneven Product Wall Thickness: If the flow and cooling speed of plastic in the mold are not consistent, it is easy to cause uneven product wall thickness, especially in the curved or complex shapes of the product.
- High Requirements for Raw Materials: Blow moulding technologies require high viscosity of raw materials, so it is necessary to carefully choose the plastics used for processing. For certain products with special performance, such as those that require early drying, budget and time will be increased.
- Limited Product Size Range: Plastic blow moulding technologies are suitable for processing products with larger dimensions. For products with smaller diameters or thinner wall thicknesses, blow molding processing is difficult, and manufacturers may need to consider changing the processing technology.
Types of Advanced Blow moulding Technologies
Blow moulding technology is mainly divided into stretch blow molding, extrusion blow molding, injection blow molding, double-layer blow molding, and also includes 3D blow molding.
- Extrusion Blow Moulding
This blow molding technology mainly involves extruding a tubular billet and injecting compressed air to expand it, tightly adhering to the inner wall of the mold cavity. After cooling and solidification, various hollow products are obtained by molding. This process can be divided into two parts, namely the manufacturing of the mold and blow molding. This blow moulding technology has high manufacturing efficiency, uniform billet temperature, and a wide range of dimensions and wall thickness. The products produced by extrusion blow moulding technologies have high compressive strength and simple mechanical equipment.
- Injection Blow Moulding
The injection blow moulding technology mainly uses injection equipment to inject molten plastic into the injection mold, forming a tubular billet. Then, it is moved into the blow molding mold while it is hot, closed and compressed air is introduced to blow and expand the billet tightly against the inner wall of the mold. After pressure holding, cooling, and exhaust, the mold is opened and the formed plastic part is taken out. The handicrafts produced by this type of blow molding technology have no seams, do not require too much post-processing, have high accuracy, consume less raw materials, have a more uniform wall thickness, and have high manufacturing efficiency. However, mechanical equipment projects for this type of blow molding technology require significant investment, long production cycles, and high requirements for processing operators.
- Stretch Blow Moulding
Stretch blow moulding technology is a type of blow molding process that involves biaxial directional stretching, which is an improvement and development of ordinary blow moulding techniques. This process first uses extrusion or injection methods to form tubular billets, then heats the billets to a suitable temperature, and undergoes longitudinal stretching under internal or external mechanical forces. At the same time, or later, transverse stretching is carried out by compressed air blowing to obtain hollow products. The characteristics of this type of blow moulding technology are low scrap rate of products, high manufacturing efficiency, easy quality control, high toughness, rigidity, strength compatibility, and smoothness, as well as good barrier and air tightness. However, the temperature control regulations for this type of blow moulding technology are relatively high.
- Double Layer Blow Moulding
The emergence of double-layer blow moulding technology is to meet certain industries that require high packaging airtightness and chemical properties, such as pharmaceuticals, food, and cosmetics. The basic process principles of this type of blow moulding technology are the same as those of single-layer product blow moulding technology, mainly composed of co-extrusion blow moulding technology and injection moulding blow moulding technology. When using the co-extrusion method, different resins can be simultaneously squeezed into multiple layers of the machine head to form a billet and then blow molded. When using injection molding, first inject a layer onto the male mold, then immediately change the mold cavity, inject a second layer onto the first layer, repeat the operation to form a multi-layer blank, and then add blow molding. This type of blow moulding technology can greatly improve the physical and mechanical equipment performance of plastic containers and enhance container performance.
Improvement of Blow Moulding Technologies
If modern blow moulding technologies remain unchanged, they will be eliminated. Many manufacturers have urgently proposed some improvement methods.
- Improve the Flow Channel Structure
There are various forms of flow channels in the machine head of blow moulding hollow molding equipment. Some channels have dead corners due to their structure, which can easily cause two long stains on the clamping line position of light or low-transparency hollow blow moulding products. This is very unfavorable for the improvement of blow moulding technologies. When manufacturers produce light-colored, low-transparency products such as primary color, yellow, and milky white, they require that the hollow blow molded products produced are free of impurities, and the machine head must be thoroughly cleaned. The time required to remove stains is approximately two-thirds of the entire washing time. At this point, improving the flow channel structure becomes particularly important. Manufacturers need to minimize the design of turns or design rounded corners to reduce structural dead corners, which is beneficial for the improvement of blow moulding technologies.
- Debugging Sufficient Power
The power configuration of blow molding hollow forming equipment is also a crucial aspect of improving blow moulding technologies. Many equipment suppliers choose to reduce power configurations to reduce costs and energy consumption, especially for motors and oil pumps used in hydraulic systems, with power even reduced by 30% to 40% from the original level. Although an accumulator has been added to the oil circuit, when using the new machine, the pressure will be relieved by 20-30kg. After the action is completed, the pressure will gradually recover. Although it is not a big problem for temporary use, it is very unfavorable for the improvement of blow moulding technologies. Therefore, manufacturers cannot cut corners and each injection molding equipment must be equipped with sufficient power.
- Expand Water and Gas Pipelines
The inner diameter of the water and air pipelines of small and medium-sized blow molding hollow forming equipment is generally only 8mm, and the flow rate of cooling water and compressed air through the pipelines is not large enough, resulting in slow forming and cooling speed and long production cycle. At this point, to improve blow moulding technologies, manufacturers can appropriately expand water and gas pipelines, accelerate cooling and molding speed, and improve efficiency.
- Design a Reasonable Screen Cleaning Structure
When improving blow moulding technologies, to ensure the safety of the machine head, such as extrusion blow molding hollow molding equipment, a screen can be installed in front of the screw head of the extruder to isolate impurities other than plastic. After a long period of use of the equipment, when it is necessary to clean impurities on the screen, it is necessary to separate the connection between the machine head and the extruder, which takes a long time. At this time, the cleaning structure of the screen can be modified or redesigned to achieve the effect of improving blow moulding technologies.
The improvement of blow molding technologies is very urgent. To a large extent, the advanced level of blow molding technology determines the accuracy of products and the quality of blow molding services.
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