Blow Molding Machines and Their Uses
Blow molding machines produce hollow-bodied plastic workpieces that serve a variety of purposes in many industries. This versatile manufacturing process is used to create bottles, jars, and other containers for various products that are essential in our daily lives.
Plastic resin is fed into the machine and heated to form a preform called a parison. This is then clamped in a mold and inflated with compressed air.
Extrusion Blow Molding
In the extrusion blow molding process (EBM), plastic pellets are fed into an extruder, which uses friction to heat the pellets to a liquified state. The molten material is then extruded into a hollow tube, known as a parison, which is captured between two mold halves as they close to form the shape of the finished product. Pressurized air is then blown into the parison to inflate it and conform it to the mold’s shape. After the inflated part is cooled, it’s trimmed to remove any excess plastic around the perimeter of the product, and then sent for secondary processes like post-mould decorating or welding.
EBM is a high-volume, low-cost manufacturing method that can produce hollow parts from polymers like HDPE and LDPE. These products include containers for liquids and detergents, as well as food packaging like bottles and jars.
The nozzles on an extrusion machine are designed to direct the plastic into a hot runner manifold, which is attached to a core pin. The core pin is rotated to a blow molding station, where the injected polymer is inflated into the desired shape. The blown plastic is then cooled, and the core pin is removed. Any molded plastic that extends beyond the mold’s pinch line is called flash and must Forming Machine be trimmed off to produce a finished product. The trimmed flash can be granulated and fed back into the raw materials stream feeding the extruder for reprocessing, but this is only possible with single material parts.
Injection Blow Molding
Injection blow molding is a three-step process that produces hollow plastic parts. It begins with the injection of plastic into a preform mold, which looks like a test tube with a metal core rod in the center. This preform is clamped into a cavity mold, where compressed air is blown into it to form the finished shape. The resulting product is then indexed to a removal station and ejected from the machine.
One unique advantage of this process is that the plastic can be biaxially oriented. This results in greater tensile and tear strength, improved barrier properties and better transparency. However, this can only happen if the plastic is oriented during the injection stage.
The injection process is also a very energy-efficient way to make PET bottles and containers. It’s important to work with a trusted source for the machinery used in this type of production. A good source will offer the best machines from well-known manufacturers, such as Jomar, and can provide expert customer service to ensure you purchase the correct machinery for your specific needs. They can even help you customize your equipment to fit with your specific application. For example, if you need to produce PET bottles and containers with both a barrier and a transparent layer, the right supplier can offer co-injection technology that allows two different resins to be combined in a single 3-layer melt stream, allowing for total control of barrier placement and thickness.
Vacuum Blow Molding
Blow molding is a manufacturing process that involves blowing air Forming Machine factory across heated plastic that’s placed on top of a mold cavity. This air forces the heated plastic to stretch across the interior walls of the mold cavity, resulting in a hollow plastic object. This process is often used to produce bottles and containers of various shapes and sizes. The majority of modern-day plastic containers store liquids and can be made using this method.
Like injection molding, vacuum forming is an alternative to blow molding and a common process in the production of plastic containers. This process utilizes a framework to hold the heated, pliable sheet of plastic while a vacuum source is turned on to suck the plastic into place around the mould shape. Once the plastic has cooled, the framework is removed and the excess plastic can be trimmed off to give the final product.
Vacuum forming uses low forming pressures, allowing for cheap tooling and fast fabrication times. This makes it ideal for prototype and low volume products and can be combined with 3D printing to speed up development and reduce costs. It can also be applied to more complex designs and parts with tight radii such as closures, workboxes, fruit and food boxes. However, this is not recommended for parts with very high draft angles.
3D Blow Molding
With the help of 3D printing, companies can prototype blow-molded products much faster. This allows for reduced flash, smooth component integration and accelerated production speed. Advances in PolyJet and FDM technology have improved the build quality, durability, surface finish and cost of 3D printed prototypes. This technology has become increasingly affordable and widely available, making it a valuable tool for companies that use the blow-molding process to produce plastic parts.
This technology can be used to manufacture plastic pipes that have a complex shape. It can eliminate failure-prone parting lines and minimize flash in hollow products. It can also improve wall thickness distribution and allow for greater material savings. In addition, it can be used to make products with a high degree of flexibility.
Kautex Maschinenbau, for example, offers a machine that uses three-dimensional blow molding to make ducts and tubes. Its 3D ducting machine, which is not closed on the upper half of the mold, is able to reduce scrap by depositing preforms at the start and end of the tube instead of throughout its entire length. It can also minimize the need to trim the bellow areas, resulting in reduced material waste.
Although the process has made inroads into Europe for applications like air ducts on turbo-charged diesel (TCD) cars, it has yet to gain traction in the U.S. But it has potential for a wide variety of applications including specialty coolant ducting, fuel filler pipes and seamless door handles.
