Nitrogen generation system used in injection molding processes

Nitrogen generation in injection molding primarily provides an inert, dry environment to prevent plastic oxidation and degradation. It is widely utilized for Gas-Assist Injection Molding (GAIM), mold blanketing, core pulling, and internal cooling. This ensures flawless surface finishes, prevents shrinkage, and reduces production cycle times.

1. Gas-Assist Injection Molding (GAIM)

In GAIM, pressurized nitrogen is injected into the mold cavity after it is partially filled with molten polymer.

• Hollow Channels: The nitrogen gas pushes the molten plastic against the cavity walls, creating hollow sections. This reduces material usage and part weight without sacrificing structural integrity.
• Shrinkage Control: As the plastic cools and shrinks, the continuous nitrogen pressure compensates for the volume loss, eliminating sink marks and warping.
• Improved Strength: Produces highly rigid parts with excellent dimensional stability, ideal for automotive components (e.g., handles, intake manifolds).

2. Mold Blanketing

• Oxygen Displacement: Nitrogen displaces the ambient air inside the mold cavity prior to the molten plastic injection.
• Preventing Degradation: Because nitrogen is inert and extremely dry, it prevents the moisture and oxygen in the air from oxidizing the polymer at high temperatures. This eliminates surface blemishes, discoloration, and material degradation.

3. Accelerated Cooling & Core Pulling

• Internal Cooling: Nitrogen gas can be circulated inside the molded part (hollow sections) to cool the plastic from the inside out. This significantly reduces cycle times and increases overall manufacturing throughput. [1, 2]
• Core Mechanisms: Nitrogen is sometimes used to actuate internal moving mold parts and core pins, offering a clean, oil-free alternative to hydraulic cylinders.

4. Raw Material Protection

• Hopper and Tank Blanketing: Molten plastic is highly susceptible to oxidation and moisture absorption before it even reaches the injection nozzle. Using nitrogen to continuously blanket the storage tanks and hopper loaders ensures the polymer retains its mechanical properties.

packaging industry, particularly the plastic packaging sector, is one of the important application areas for nitrogen generators. During the packaging of food, pharmaceuticals, and other easily oxidizable materials, nitrogen generators are used to remove oxygen from packaging containers or bags. By filling with nitrogen, the shelf life of food and pharmaceuticals can be extended, oxidation and bacterial growth can be prevented, and the freshness and quality of products can be ensured. In addition to the above applications, nitrogen generators have other important uses in the plastic manufacturing industry. For example, they can be used in the foam plastic manufacturing process to control bubble structure, providing lightweight and insulating properties. Furthermore, nitrogen generators can serve as protective gas in plastic welding processes to improve the quality and strength of weld joints.

In summary, nitrogen generators play significant roles and offer advantages in the plastic manufacturing industry. They can act as protective gas to prevent oxidation and discoloration of plastic products; provide cooling and pressure stability during extrusion; extend freshness periods during packaging; and offer control and protection in foam manufacturing and welding processes. The application of nitrogen generators helps improve the quality, appearance, and performance of plastic products, thereby driving the development of the plastic manufacturing industry.