How much pressure is the best blow molding machine

The optimal working pressure of the blow molding machine needs to be set according to the preform material, bottle design and process requirements, usually in 2.5 to 4.0 MPa (25 to 40 bar) between. The following are specific instructions and optimization suggestions:

1. core pressure range

1. conventional PET bottles
   • standard Range: The blowing pressure is usually 2.5 to 4.0 MPa (25 to 40 bar) between, 3.5 to 4.0 MPa (35 to 40 bar) for the most commonly used range, suitable for carbonated beverage bottles, mineral water bottles and other standard containers.
   • Process basis: PET material needs to be heated and inflated, and the pressure needs to match the temperature to ensure that the preform is fully attached to the mold to avoid over-pressure rupture or under-pressure molding incomplete.
2. glass bottle
   • pressure range: Low blowing pressure, approx. 0.2 to 0.5 MPa (2 to 5 bar), The molten glass is inflated by compressed air, which is suitable for beer bottles, daily glass containers, etc.
3. Special Bottle Type
   • thick wall or large industrial barrels: Higher pressure required (close 30 bar and above) To ensure that the thick-walled material is completely inflated, suitable for chemical barrels, liquid storage tanks, etc.
   • High performance engineering plastic bottle: Due to the high hardness of the material, it is necessary pressure above 30 bar, such as special containers for the aerospace or automotive industries.
   • High precision bottle type(such as pharmaceutical packaging): need to stabilize the high pressure ( 35 to 40 bar) to ensure dimensional accuracy, wall thickness uniformity and appearance quality.

2. pressure setting basis

1. preform characteristics
   • PET preforms need to be heated (usually above 200 ℃) after blowing, and the pressure needs to be adjusted in coordination with the heating temperature. Imported PET raw materials are easier to inflate than domestic materials, and the process parameters need to be fine-tuned when the production date of the same batch of bottle blanks is different.
2. Equipment Capability
   • high-capacity equipment requires higher pressure to maintain efficiency, but needs to balance energy consumption and stability. For example, equipment that produces 100 bottles per minute needs to match a compressor with sufficient displacement.
3. Industry Standard
   • GB/T 3853-2018: The energy efficiency rating of the air compressor is specified, which indirectly affects the choice of bottle blowing pressure, and the first level of energy efficiency equipment is preferred to reduce long-term costs.
   • JB/T 13963-2020: Clear the technical specification of reciprocating piston air compressor for bottle blowing, rated discharge pressure 3.0 to 6.0 MPa (30 to 60 bar) covering mechanical performance, safety protection and noise control indicators.
   • GB/T 44359-2024: For lightweight PET bottle molds, core indicators such as bottle blowing pressure are specified to optimize energy consumption and quality and promote the green transformation of the industry.

3. practice adjustment points

1. pre-blowing pressure control
   • adjust according to bottle specifications: large capacity bottles need lower pre-blowing pressure, high capacity equipment needs higher pressure. For example, when producing carbonated beverage bottles (pressurized bottles), the pre-blowing pressure is close to 4.0 MPa (40 bar); ordinary non-pressurized bottles can be appropriately reduced.
2. Adaptation of materials to environment
   • special materials (such as glass fiber reinforced PET) require a small pre-blowing pressure to be molded, while the storage of over-standard or secondary heating of the preform to reduce the heat input, the corresponding reduction in pressure.
   • The production environment should be constant (room temperature, low humidity) to avoid temperature fluctuations affecting pressure stability.
3. Balance between safety and efficiency
   • high risk of stress: It may cause the bottle to break and the mold to wear faster. The maximum pressure should be limited by the pressure regulating valve and the pressure sensor should be checked regularly.
   • Effect of insufficient pressure: Causing uneven thickness of the bottle wall and incomplete molding, it is necessary to ensure that the compressor displacement meets the production requirements (considering the margin and pipeline loss).
   • Energy consumption optimization: Adopt variable frequency motor or three-stage compression technology to reduce power consumption while meeting pressure requirements. For example, three-stage compression can improve volumetric efficiency and reduce heat generation.

4. Summary

the pressure of bottle blowing machine needs to be comprehensively set in combination with specific bottle type, materials and equipment capabilities. Industry specifications provide the basic framework (e.g. GB/T 3853-2018, JB/T 13963-2020). In actual production, the best balance needs to be achieved through process debugging (e.g. pre-blowing pressure adjustment), environmental control (constant temperature and low humidity) and equipment selection (e.g. oil-free compressor, frequency conversion technology) to ensure product quality and production efficiency.