Plastic Blow Molding
The basic working principle of plastic blow molding is to inflate the softened thermoplastic billet, making it tightly adhere to the cooling surface of the closed mold. The inflated billet solidifies, forming a hollow plastic product.
Blow Mold Suppliers: Machines and Processes
Suppliers need to choose blow molding mold and equipment that can meet the quality and precision requirements of production and can complete the entire plastic blow molding process completely and quickly. The process of extruding or injecting thermoplastic into a tubular billet, then heating and softening it before placing it into a mold. Compressed air is then introduced to blow the billet tightly against the mold wall, and after cooling and demolding, the molded part is obtained.
How to Choose Additives for Blow Mold Suppliers?
Suppliers need to add appropriate additives during blow mold processing to prevent various problems. Common additives include lubricants, plasticizers, colorants, stabilizers, and coolants. Regardless of the type of additive, when selecting, attention should be paid to whether it is compatible with plastic raw materials, whether it can maintain long-term stability of plastic parts, whether there will be repulsion between different additives, whether there are indicators that meet product requirements, and whether the cost-effectiveness is appropriate.
- Selection of Plasticizers
Plasticizers are additives that make plastics easier to process, and their selection should consider factors such as volatility, high-temperature resistance, and light resistance. Plasticizers are mostly used in PVC injection molding, which can be divided into soft and hard materials. Therefore, when selecting plasticizers for blow molding, mold suppliers need to consider whether they are compatible with PVC materials and whether the growth efficiency is high.
- Selection of Lubricants
Lubricants are mainly used by suppliers to reduce the friction generated during the processing of blow molding mold and equipment, enhance the fluidity of plastic raw materials, and make the surface of the parts smoother. The lubricant of the blow molding machine should have good heat resistance to avoid decomposition and loss of effectiveness caused by the heating of plastic during use; At the same time, it should have compressive strength and be able to adhere to the surface of the mold under strong pressure, continuing to provide lubrication. Suppliers should ensure that lubricants are evenly distributed and do not affect the molding of plastic parts during the operation of blow mold.
- Selection of Coloring Agents
When producing products using blow molding molds, most raw materials require the addition of coloring agents to make the products more aesthetically pleasing. When adding colorants, the color power of the colorants should be considered. The stronger the coloring power, the fewer colorants will be used; Due to the direct contact between colorants and raw materials, suppliers need to consider the hygiene conditions of colorants used in blow mold and choose non-toxic colorants that meet hygiene standards; Colorants should have good heat resistance and be able to maintain the bright color of plastic parts even during high-temperature processing in blow molding machines.
- Selection of Stabilizers
Stabilizers are usually divided into light stabilizers and heat stabilizers. Heat stabilizers can protect materials from degradation at high temperatures, and blow mold suppliers should choose sanitary and preferably odorless materials. Light stabilizers can slow down the brittle aging of plastic parts under sunlight exposure, prolong the service life of plastic parts, and improve their value. The selected light stabilizer should have good heat and ultraviolet resistance, and should not react with other chemical agents during use, to have a stable and long-lasting effect.
- Selection of Coolant
The suitability of the coolant selected by the suppliers directly affects the cooling effect of the blow mold and blow molding machine, as well as the normal demolding of the mold. When choosing a coolant, it is necessary to consider the specific requirements of the mold and the production environment. Water cooling, oil cooling, air cooling, or gas cooling can be chosen. Efficient and stable water cooling; Oil cooling has strong thermal conductivity and is suitable for production processes with high temperature control; Air cooling is simple and convenient, but the effect is slow; Gas cooling is fast and uniform.
Selection of Blow Molding Machine
When choosing a blow molding machine, blow mold suppliers need to consider many aspects, including their own production needs, product and mold size, technical parameters, blow molding machine quality, price, brand, and machine flexibility. Only by considering them comprehensively can they obtain the most suitable equipment for themselves.
- Production Requirements: Firstly, suppliers will evaluate their production requirements for blow molding mold, including the shape of the mold, the size and accuracy of the product, etc. If the requirements are high, it is necessary to choose a relatively precise blow molding machine.
- Technical Parameters: Technical parameters are specified based on the production needs of the supplier, such as the speed, temperature, pressure, etc. of blow mold processing. These parameters should be compatible with the blow molding equipment to ensure smooth production of the blow molding machine.
- Quality of the Machine: Suppliers need to consider the quality of the blow molding machine when purchasing. If it is not a brand new blow molding machine, they need to understand the reasons to prevent serious defects in the equipment.
- Price: The price of blow molding machines is a key factor that suppliers value. On the premise of meeting the production needs of blow molding molds, equipment should be selected with high cost-effectiveness as much as possible.
- Brand: When suppliers purchase blow molding machines, they need to focus on the brand reputation and advantages of the injection molding machine, such as whether the user’s sharing or promised after-sales service is complete, and whether the seller can provide high-level maintenance services after purchasing the blow molding machine.
- Flexibility and Compatibility: When selecting a blow molding machine from a supplier, it is necessary to consider whether it can adapt to multiple blow molding molds and whether mold replacement can be carried out smoothly in the later stage.
What are the Classifications of Blow Molding Machines?
Suppliers should choose blow molding mold and equipment based on their purposes. According to the production method of the preform, it can be divided into extrusion blow molding machine, injection blow molding machine, stretch blow molding machine, and multi-layer blow molding machine.
- Extrusion Blow Molding Machine
Principle: Extrusion blow molding machine is a process of extruding molten plastic raw materials through a screw to form a tubular billet, placing it into a mold, closing the mold for inflation, and then cooling and solidifying to form a molded part.
Composition: The extrusion blow molding machine is mainly composed of an extrusion system, a transmission system, a heating and cooling system, and a control system.
Application: It can mainly process plastics such as polyethylene, polypropylene, and polyvinyl chloride, and is widely used in plastic packaging. however
Defects: Extrusion blow molding machines are prone to uneven wall thickness, warping and deformation, contamination of inner and outer walls, unclear graphics and text on the surface of plastic parts, excessive and thick burrs, cracking, and other defects during the processing.
- Injection Blow Molding Machine
Principle: Firstly, the plastic needs to be plasticized and injected into an injection mold to form a tubular billet. After molding, it is moved into a blown film, and then compressed air is introduced to blow and cool the billet to form.
Composition: The injection blow molding machine includes a plasticizing system, hydraulic system, electronic control system, and transmission system.
Application: Injection blow molding machines are widely used in various industries such as food, transportation, chemical, and public environmental facilities.
Defects: Products produced by injection blow molding machines are prone to defects such as material shortage, edge overflow, adhesive drawing, nonmolding, easy cracking or thinning, and neck cracking during production.
- Stretch Blow Molding Machine
Principle: The stretch blow molding machine first extrudes or injects the preform, then heats it to the appropriate temperature, performs longitudinal stretching, and finally introduces compressed air. After cooling, it is demolded to form the product.
Composition: The stretch blow molding machine mainly consists of a heating system, a power system, a stretching device, a feeding device, a cooling and shaping device, and a preheating device.
Application: Stretch blow molding machines are mainly used in the production of plastic bottles, barrels, plates, tableware, etc. They have high production efficiency and high material utilization.
Defects: During the production process of stretch blow molding machines, it is easy to encounter defects such as uneven billet wall thickness, offset gate position, spots on the surface of the product, and deformation and wrinkling of the product.
- Multi-Layer Blow Molding Machine
Principle: Multi-layer blow molding first heats the plastic to form a tube shape, and then expands it into a hollow container through air compression inside the mold. This manufacturing technique is suitable for producing multi-layer blow-molded products.
Composition: The multi-layer blow molding machine mainly consists of a plasticizing system, a die extrusion system, and a blow molding system.
Application: Multi-layer blow molding machines are widely used in food packaging, agriculture, industry, and other fields, producing products with high strength and transparency.
Defects: The multi-layer blow molding machine is prone to unstable discharge, surface bubbles, rough products, and uneven wall thickness during operation.
Blow mold suppliers need to thoroughly understand their own needs and product requirements when selecting corresponding blow molding molds and equipment, to obtain the fastest efficiency and highest quality products.
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