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How does a blowing machine work

A blowing machine, also known as a blow molding machine, is a mechanical device used in the manufacturing industry to produce hollow plastic parts and containers. This article aims to provide a comprehensive understanding of how a blowing machine works and the various processes involved.

The Basic Operation

At its core, a blowing machine operates by inflating a hot plastic preform, which is a small tube-like structure, with compressed air to form a desired shape. The machine consists of several key components that work in conjunction to achieve this process.

Heating and Melting

The first step in the blowing machine process is the heating and melting of the plastic material. Granules or pellets of plastic are fed into the machine’s hopper, which then transfers them into an extruder. The extruder consists of a heated barrel and a rotating screw. As the plastic material moves through the barrel, it is heated to a molten state, thanks to the friction generated by the rotating screw and electric heaters.

Once the plastic material reaches the desired melting temperature, it passes through a die head, which shapes it into a hollow tube known as a parison. The length and diameter of the parison can be adjusted to achieve different sizes and shapes of the final product.

Inflation and Cooling

After the parison is formed, it is transferred to the mold, where the actual blowing process takes place. The mold consists of two halves, typically made of metal, that have the desired shape carved into them. The mold halves are then clamped together, enclosing the parison within.

Compressed air is injected into the parison through a hollow rod known as a blow pin. The pressure of the air causes the parison to expand and reach the inner walls of the mold, taking its shape. The mold is designed with proper cooling channels to aid in the quick solidification of the plastic, ensuring that the desired shape is maintained.

Finished Product and Ejection

Once the plastic has solidified and cooled down, it is time to remove the final product from the mold. The blowing machine’s clamp is released, allowing the mold halves to separate. The newly formed plastic part, now cooled and solid, is ejected from the machine using an ejection system, such as air or mechanical pins.

The plastic parts created by the blowing machine can undergo additional processes like trimming, labeling, or packaging, depending on the specific requirements of the manufacturing process.


A blowing machine plays a crucial role in the production of various plastic products and containers. By understanding the basic operation of this machine, one can appreciate the intricate processes involved in creating hollow plastic parts. From heating and melting the plastic material to inflating and cooling it in a mold, each step contributes to the final product’s shape and quality.

As technology continues to advance, blowing machines are becoming more efficient, allowing manufacturers to produce plastic products at a faster rate while maintaining high standards of quality and precision.

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