How does an injection blow moulding machine work?

Injection blow moulding is a popular manufacturing process used to produce hollow plastic products such as bottles and containers. This process combines injection moulding and blow moulding to create high-quality, seamless plastic parts. One of the key components in the injection blow moulding process is the injection blow moulding machine. In this article, we will take a closer look at how an injection blow moulding machine works, its components, and the overall process.

Injecting blow moulding machines come in various designs and configurations, but they generally follow the same core principles. These machines are equipped with multiple stations for each stage of the injection blow moulding process, including injection, blowing, and ejection. The machine's ability to automate these processes ensures consistent production of high-quality plastic parts at a fast rate, making it a popular choice for manufacturers in various industries.

Injection Unit

The injection unit of an injection blow moulding machine is responsible for melting and injecting the plastic material into the mould cavity. This unit typically consists of a hopper, barrel, screw, and nozzle. The plastic material is fed into the hopper, where it is then heated and melted in the barrel. The screw then pushes the molten plastic through the nozzle and into the mould cavity.

The injection process begins when the mould closes and the injection unit pushes the molten plastic into the mould cavity under high pressure. The plastic material takes the shape of the mould cavity and begins to cool and solidify. Once the plastic has solidified, the mould opens, and the injection unit retracts, leaving the plastic part inside the mould.

Blow Moulding Unit

After the injection process is completed, the next stage of the injection blow moulding process is the blow moulding unit. This unit is responsible for stretching and blowing the plastic part to its final shape. The blow moulding unit typically consists of a blow pin, core rod, and mould cavity.

The blow moulding process begins when the blow pin extends into the mould cavity and stretches the plastic part to its desired shape. Compressed air is then blown into the plastic part, forcing it to expand and take the shape of the mould cavity. The plastic part is then cooled and solidified, ensuring that it maintains its shape and dimensions.

Ejection Unit

Once the plastic part has cooled and solidified, the final stage of the injection blow moulding process is the ejection unit. This unit is responsible for removing the plastic part from the mould cavity without damaging it. The ejection unit typically consists of ejector pins, air blasts, and robotic arms.

The ejection process begins when the ejector pins push the plastic part out of the mould cavity. Air blasts may be used to help release the part from the mould. Robotic arms may also be used to assist in removing the part from the mould and transferring it to the next stage of the production process.

Control System

Injection blow moulding machines are equipped with advanced control systems that monitor and regulate the various stages of the moulding process. These control systems ensure that the machine operates efficiently and produces high-quality plastic parts consistently. The control system may include features such as temperature control, pressure monitoring, and cycle time optimization.

The control system allows operators to input specific parameters for each stage of the injection blow moulding process, such as injection speed, blow pressure, and cooling time. The system then automatically adjusts these parameters to ensure that the machine operates within the specified limits. This level of automation helps to reduce the likelihood of human error and ensures that the manufacturing process runs smoothly.

Mould Design

One of the key factors that influence the success of the injection blow moulding process is the design of the mould. The mould must be designed to accommodate the shape and dimensions of the desired plastic part, as well as the specific requirements of the injection and blow moulding units. Mould design considerations include wall thickness, draft angles, and parting lines.

The mould is typically made of steel or aluminum and is precision-machined to ensure accuracy and durability. The mould is also equipped with cooling channels that help to regulate the temperature of the plastic material during the moulding process. Proper mould design is essential to achieving high-quality plastic parts with consistent dimensions and surface finish.

In conclusion, injection blow moulding machines are an essential tool in the manufacturing industry for producing hollow plastic products. These machines combine injection moulding and blow moulding to create seamless plastic parts with high accuracy and efficiency. By understanding how injection blow moulding machines work and the importance of their components, manufacturers can optimize their production processes and deliver high-quality plastic parts to their customers.