Blow moulding is a widely used manufacturing process primarily for producing hollow plastic parts. It involves inflating plastic inside a mould cavity to form a desired shape. The process has revolutionised industries by enabling the creation of complex, lightweight, and durable plastic products, including bottles, containers, and other items commonly found in everyday life.
The Blow Moulding Process
Blow moulding can be broken down into three main stages: extrusion, inflation, and cooling. The process begins with the creation of the preform or parison. In the case of extrusion blow moulding, a plastic resin is fed into an extruder, where it is heated and formed into a tube-like shape. This tube is then clamped inside a mould, and air is blown into it, causing the plastic to inflate and take the shape of the mould cavity.
The mould is then cooled, solidifying the plastic. After cooling, the mould is opened, and the final product is ejected. The blow-moulded piece may undergo additional finishing processes, such as trimming or surface treatment, to meet specific quality standards.
Types of Blow Moulding
There are three primary types of blow moulding: extrusion blow moulding, injection blow moulding, and stretch blow moulding. Each type has its unique applications, advantages, and limitations.
1. Extrusion Blow Moulding (EBM):
This is the most common type of blow moulding and is used to produce large, hollow items such as containers, bottles, and tanks. In EBM, the plastic material is extruded into a tube, which is then inflated inside a mould. This method is highly efficient for producing high-volume products at a relatively low cost, making it ideal for mass production.
2. Injection Blow Moulding (IBM):
In IBM, the process starts with injecting molten plastic into a mould to create a preform, which is a small, hollow object. The preform is then transferred to a blow mould, where it is inflated into its final shape. This process is ideal for making small, high-precision items, such as pharmaceutical bottles and cosmetics containers. IBM offers greater control over product consistency and can produce complex shapes with thinner walls compared to extrusion blow moulding.
3. Stretch Blow Moulding (SBM):
This process is used to create bottles and containers, typically for beverages and other consumer goods. In SBM, a preform is first injection moulded, then heated and stretched both axially and radially before being blown into a mould. This method allows for the production of containers with higher strength and clarity, particularly suited for applications requiring transparency, such as water and cold drink bottles.
Materials Used in Blow Moulding
Blow moulding utilizes a variety of thermoplastic materials, with polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) being the most common. Other materials such as polyethylene terephthalate (PET) are often used for applications requiring high durability and clarity. The choice of material depends on factors such as the intended use of the product, environmental conditions, and required strength.
Advantages and Applications
Blow moulding offers several advantages, including the ability to create complex shapes, high production speeds, and cost efficiency for high-volume manufacturing. It also allows for the creation of thin-walled structures, reducing material waste and lowering costs. Additionally, blow moulding can be used to produce both large and small objects, making it highly versatile.
Blow-moulded products are used across a wide range of industries. Many of Pneutech’s customers specialise in the production of plastic bottles for beverages, detergents, and personal care products, other applications include automotive parts, industrial containers, and medical devices.
The MAC & PHD Advantage
Blow moulding is generally a high cycle, high speed, repetitive motion that requires valves and actuators capable of hundreds of millions of operations.
MAC Valves and PHD actuators are the market leaders in the Blow moulding industry due to the ability of the products to withstand the consistent cycle rate demands and provide the repeatability in that response that is required in these demanding often 24/7 operations.
Furthermore, installing MAC valves and PHD actuators onto a customers equipment allows the opportunity for greater throughput and less unscheduled downtime. This is largely due to the fast response characteristics of these products, the very high flow of the valve for its port size whilst in a small package and the customised vast product array developed specifically for the blow moulding industry over the last 50 yrs.
MAC Valves are exceptional at dealing with ingress from air contamination. This allows them to provide longer service life in challenging environments and improve efficiency on the whole blowing process, often reducing cycle times.
We regularly hear from customers how they are amazed at the consistent performance of the product for so many years compared to what they used to have on their equipment.
If you'd like to discuss how we can help find effeciencies in your business, get in touch with Mike, our Blow Moulding specialist, on 0418 995 337 or email, mike@pneutech.com.au