Gas-Assisted Plastic Injection: Optimise Your Thick and Complex Parts

Gas-assisted injection is an innovative process that allows for the manufacture of plastic parts that are hollow, lightweight, and have no surface defects. For hardware product designers, this technology resolves the major challenge of thick-walled parts: eliminate shrinkage while reducing weight.

What is Gas-Assisted Injection Moulding (GAIM)?

The principle relies on the introduction of an inert gas (generally’nitrogenunder high pressure inside the still-molten plastic material in the mould.

The gas follows the path of least resistance, creating a hollow channel at the centre of the part. It presses the material against the mould walls until complete solidification, acting as a dynamic «internal core».

Advantages and Disadvantages of Gas Injection

✅ The Advantages

1. Removal of shrinkage The gas exerts a constant pressure from the inside, preventing matter from collapsing towards the centre, even in very thick regions.

2. Structural relief Reduction in material usage (up to 30–40% weight saving) without compromising rigidity.

3. Reducing internal tensions Less warping (distortion) after demoulding, which ensures better dimensional stability.

4. Design freedom: Allows combining thin walls with very thick sections (ribs, handles) on the same part.

❌ Disadvantages

1. Hollow parts only: The process inevitably creates an internal void; it is unsuitable for parts that need to be solid for specific mechanical reasons.

2. Complex technical mastery The positioning of the gas injectors and the injection timing are critical to prevent gas from «piercing» the workpiece surface.

3. Equipment costs: Requires a gas control unit and a high-pressure nitrogen source in addition to the standard press.

Typical applications of Gas-Assisted Injection

AI is the preferred solution as soon as you move beyond the standard «fine» element.

• Furniture and Design Chair legs, armrests, furniture handles (solid appearance but feather-light).

• Car Grab handles, mirror supports, air ducts, and seat structures.

• Domestic appliances Oven handles, washing machine porthole frames, rigid vacuum cleaner structures.

• Sport and Leisure: Exercise bike frames, hockey sticks, gardening equipment.

Usage for Hardware Products

For a hardware engineer, gas injection is a valuable ally for optimising the chassis and the’Outer casing.

Structural reinforcement without superfluous weight

If your product requires a rigid frame to support heavy internal components (batteries, motors), gas injection allows for the creation of rigid internal tubing that acts as an exoskeleton for the product, while remaining lightweight for the end-user.

2. Premium Aesthetics on Large Parts

On «high-end» hardware products (speakers, interactive kiosks), sink marks (surface indentations) are unacceptable. Gas injection allows for perfectly flat outer walls, even when massive fixing ribs are located directly behind them.

3. Integration of transition functions

The hollow channel created by the gas can sometimes be used (after study) to facilitate the passage of cables or to lighten complex hinge areas on industrial enclosures.

Comparison Table: Standard vs Gas-Assisted Injection

Expert tip: During CAD design for gas injection, it is crucial to plan the gas path. A poorly optimised design can lead to an uneven distribution of the vacuum. Always have your design validated by rheological simulation specific to gas.

Would you like to explore a specific use case for one of your hardware components to see if gas is the ideal solution?