Blow Molding Machine
Blow molding is a versatile manufacturing process that creates hollow plastic products used in various industries. The process begins with creating a shaped tube called a parison from raw thermoplastic resins like polyethylene.
The inventors of blow molding took inspiration from glassblowing. Their process allowed for mass production of a variety blow molding machine of hollow glass and plastic products.
Extrusion
Extrusion is a manufacturing process that makes tubes, rods, profiles, and sheet plastic products. It is also used to make a variety of other products such as containers, bags, and bottles for soda, oil, and cleaning products. The process begins with a melt of plastic that is forced through an extruder using either a continuous or intermittent screw mechanism. Once the plastic has been shaped into the desired profile, it is cooled by an air ring and blower. This helps the product retain its shape and ensures that it is not too thin. The cooled plastic then passes through a tractor which coils it into a continuous filament. It may then be subjected to heat treatment to help it harden.
The preforms are then blown into the final form using compressed air. This forms the parison, which is sealed at both ends and contains a hole at the neck end to accommodate the opening where the bottle will be filled.
Blow molding machines can use various materials and produce a wide range of shapes, sizes, and colors. They are widely available through multiple dealers and offer many advantages, including high production and small startup costs. They can also create a larger volume of plastic per cycle than injection molding machines and are capable of handling a variety of polymer types. However, they are not as efficient and do not have as much control over wall thickness as injection mold machines.
Blowing
A blow molding machine produces hollow plastic parts, such as bottles and containers. It uses air pressure to blow the soft molten plastic into a mold, where it is inflated and formed into the desired shape. The process is similar to glassblowing and has been used since the 1800s.
The melted plastic is first extruded into a tube called a parison, which is then captured by the machine’s clamping unit and blown with compressed air. This forces the parison into the mould cavity and expands it like a balloon. Once the plastic has cooled, it is ejected from the mould and sent on for finishing.
Various types of blow molding machines are available, each suited for different applications and production requirements. These include extrusion, injection, and stretch blow machines. The latter is designed to produce products with a biaxially oriented plastic, which improves the mechanical properties of the finished product by reducing warping and tearing, and creating a more transparent appearance.
A newer technology known as coextrusion is also used to improve the barrier properties of blow molded products by adding layers that regulate hydrocarbon emissions. This is especially important in food packaging, where barriers can keep oxygen out and preserve product quality. The process is also more cost-effective than the older four-station method of injection, reheating, stretching, and blowing.
Cooling
Blow molding is a type of plastic forming process that uses compressed air to inflate a heated plastic tube (called a parison) into the shape of a mold, creating blow molding machine factory a hollow product. It is a form of extrusion and is similar to glass blowing, with its roots dating back as far as the 1800s.
Once the hot parison has been formed it is clamped between two mold halves and blown by air pressure into the desired shape of the final product, conforming to its exact dimensions. It is then allowed to cool and harden. After the cooling process, the mold opens and the molded product is ejected.
The quality of the finished blow molded product is largely determined by the quality of its internal structure and the rate of crystallization. For these reasons, a proper cooling method is important. The Wittmann Blow Molding Booster replaces the regular blown air with chilled compressed air during the cooling process, thus reducing both the material stress in the molded product and the crystallization rate.
The BMB is an ideal cooling solution for blow molding because it is compact, easy to install and operate and offers quick return on investment, delivering 15% to 35% production increases. It also works with any quality of compressed air, requires no maintenance and is CFC free and ozone friendly.
Ejection
Injection blow molding (IBM) is used to produce hollow plastic and glass objects in large quantities. During this process, the polymer is injection molded onto a core pin, which is then rotated to a blow molding station to be inflated and cooled. After the plastic has been inflated, it is ejected from the mold.
This process uses low-pressure air to inflate a preform, known as a parison, into the shape of the finished product. After the parison has been inflated, it is cooled and then ejected from the mold. This process is commonly used to make bottles for soda, water, and cleaning products.
Injection blow molding is heavily reliant on petroleum, which has contributed to the depletion of global oil supplies and poses significant environmental risks. In contrast, stretch blow molding is a less-reliant technique that offers the potential to reduce production costs and waste. It is also more flexible than injection blow molding and can be used to create multiple shapes, including bottles, toys, bellows, blade case, tea pot, car parts, and other reusable containers. It can also be used to produce a variety of personal care products, such as shampoo, conditioner, body wash, hair gel, soap, and other cleaning products. These products can be sold in both PET and PP plastic containers. The PET container is lighter and more durable than the PP version.
