Blow Molding Machine
Blow molding is the process that produces the plastic bottles we use every day for soda, water, cleaning products, and much more. It uses compressed air to inflate the molten plastic, called a parison, into the shape of the desired product.
The plastic resin is fed into the machine via a raw material silo or hopper. Vacuum pumps draw plastic pellets from big bags or bulk containers to transfer them to the extruder hopper.
Process
Blow molding is a process that creates hollow plastic products, such as bottles and other containers. The basic principles behind this process come from glass blowing. The process involves melting the polymer, extruding it, forming the product (blowing), cooling, and ejecting the finished part. The two main types of blow molding are injection and extrusion blow molding.
The process of blow molding begins with an extruder that melts the polymer and forms it into a long, thin tube-like segment called a parison. The parison is then clamped into a product blow mold and pressurized air is blown into it. The inflated plastic shapes to the mold and after it cools and hardens, the blow mold opens and the finished product is ejected.
While the mold is being prepared, blow molding machine it’s essential to review design issues and production goals with your supplier. This ensures your commercial goals are precisely aligned with the manufacturing process, from functionality to quantity and quality expectations.
Before the blow molding process begins, the mold must be preheated and cleaned, and each hydraulic device should be tested with scrap material to verify its integrity. After the test, the machine is ready to begin its trial operation. It’s also important to check the hydraulic oil level and temperature of each device. This will help prevent overheating and damage to the equipment.
Materials
Blow molding is an adaptable process that allows for hollow plastic products to be made with a wide variety of shapes. In addition to being used for bottles and containers, this type of manufacturing can also produce other items like milk cartons, shampoo tubes, storage tanks, and even plastic drums. The key to this process is that soft, molten plastic gets inflated by air pressure. This enables the creation of many different kinds of designs that would be impossible to mass-produce with other methods.
The material that is used in blow-molding machines is usually a thermoplastic, which means it can be melted and formed into almost any shape. Common examples include polyethylene, polypropylene, and polyvinyl chloride. These materials have high tensile and abrasion resistance, excellent transparency, and strong water barrier properties. They can withstand most acids and alkalis as well.
Other materials that are used in blow molding machines include polycarbonates and modified polyesters. Polycarbonates have high impact strength and good clarity, and they can be molded into many shapes. They also have very good heat resistance and are available in several grades.
Modified polyesters are a less expensive option than polycarbonates and are used to make a variety of products. They are not as clear as polycarbonate, but they can withstand higher temperatures. In addition, they are not as brittle and are more flexible than polyethylene.
Design
Blow molding is a versatile process that is used to create many types of plastic products. These include bottles, plastic containers, and other hollow shapes. It is also capable of performing a variety of secondary operations on the finished product. These operations may include drilling, sawing, cnc routing, punching, sonic or spin welding and surface treatment. There are a limitless number of possible combinations of secondary operations that can be performed on blow molded parts.
The first step in the blow molding process is plastic feeding or charging. The plastic pellets are conveyed into the extruder hopper by vacuum pumps. Compressed air is also used to blow the melted plastic through the parison and into the mold.
Once the plastic has been blown into the mold, it is cooled and then the mold opens. The part is then ejected from the machine and sent on to any applicable finishing. Alternatively, some ISBM and EBM machines can replace the parison with a preform. This reduces the amount of time needed to blow and cool the plastic.
The design of blow molding molds requires special attention. Specifically, the distance between the inner and outer walls must be less than the combined thickness of both walls. This is referred to as the weld distance. In addition, a draft of 10deg should be designed into the mold parting line steps to prevent shear during mold close. This is especially important for multi-cavity molds.
Applications
Blow molding is used to make hollow plastic products such as bottles and containers. The process uses air pressure to blow the molten plastic into a mold, which shapes it into its final shape. The product is then cooled and ejected from the mold. Blow molding is used for a wide range of applications, from shampoo bottles and soda cans to vehicle ducting and manufacturing tubs.
A variety of auxiliary equipment can be used in the blow molding process. For example, a system can blow molding machine factory be installed to convey the plastic resin from its storage silos or hoppers to the extruder. Vacuum pumps can also transport the plastic pellets into a grinder catch bin or directly back to the hopper for a coextrusion system, where the plastic can be mixed with other ingredients.
Other auxiliary systems include a dryer, which is particularly important in the case of PET blow molding. This type of blow molding produces thin wall sections, so the dryer helps to reduce energy consumption during the drying process. Drying is an especially costly operation when using low-density polyethylene (LDPE) and high-density polyethylene (HDPE) materials. It is therefore important to find ways to reduce energy consumption in these applications. One way to do this is by employing a two-station process that eliminates the reheating stage and uses latent heat instead.
