What types of Blow Molding Machines are there?

In daily life, we will see all kinds of bottles. The emergence and development of blow molding machines have greatly improved the efficiency of daily work.

What is a blow molding machine?

Classification of blow molding machines

The advantages and disadvantages of the three processes

1、What is a blow molding machine?

It refers to a machine that blows bottles. The most direct explanation is a machine that can blow plastic particles or finished preforms into bottles through certain technological means. The blow molding machine has the advantages of convenience, quickness and large molding volume.

2、Classification of blow molding machines

Blow molding machines are mainly divided into three categories according to the process: injection molding blow molding machine, extrusion blow molding machine and stretch blow molding machine.

Injection molding

The principle of injection molding is to add granular or powdered raw materials into the hopper of the injection machine. The raw materials are heated and melted into a fluid state, enter the mold cavity, and are hardened and shaped in the mold cavity.

Extrusion molding

Extrusion molding, also known as extrusion molding, is mainly suitable for the molding of thermoplastics, but also for the molding of some thermosetting and reinforced plastics with better fluidity. The process is to use a rotating screw to extrude the thermoplastic raw material from the die, and then shape it by a sizing device, and then pass it through a cooler to make it hard and solidify to become a product with the required cross section.

Stretch blow molding 

The molten thermoplastic raw material extruded from the extruder is clamped into the mold, and then air is blown into the raw material. The molten raw material expands under the action of air pressure, adheres to the mold cavity and finally cools. The method of curing into the desired product shape.

3、The advantages and disadvantages of the three processes

Advantages of injection molding:

The molding cycle is short, the production efficiency is high, and it is easy to realize automation.

It can form plastic parts with complex shapes, precise dimensions, and metal or non-metal inserts.

Product quality is stable.

Adapt to a wide range.

Disadvantages of injection molding:

Injection molding equipment is more expensive.

The injection mold has a complicated structure.

The production cost is high, the production cycle is long, and it is not suitable for the production of single and small batches of plastic parts.

Advantages of extrusion molding：

The equipment cost is low.

The operation is simple, the process is easy to control, and it is convenient to realize continuous automatic generation.

High production efficiency, uniform and dense product quality.

By changing the die of the machine head, products or semi-finished products with various cross-sectional shapes can be formed.

Disadvantages of extrusion molding：

Limited to hollow parts.

Low intensity.

Wall pillows are usually made of mixed materials to increase their barrier properties, so they cannot be recycled.

Advantages of blow molding:

The product has uniform wall thickness and small weight tolerance.

Less post-processing and small waste corners.

It is suitable for the production of large batches of small precision products.

Disadvantage of blow molding.

Two sets of molds for injection and blow molding and a hollow core mold with a valve must be used. high cost.

The entire molding cycle is extended and production efficiency is reduced. The internal stress of the injection molding parison is relatively large. If there is uneven heat and cold, the blow molded container is prone to stress cracking.

According to the process division, it is mainly divided into these three categories, but there are many factors for its division. For example, according to the automatic division, it is divided into fully automatic and semi-automatic. The processing technology is mainly divided into one-step method and two-step method. It can be seen that there are still many types of blow molding machines, so for your needs, choose a suitable blow molding machine.