Gas Assist Injection Molding: Engineering Complexity Into Large, Lightweight Parts

When your design calls for large plastic parts with varying wall thicknesses or complex internal geometries, conventional injection molding often hits its limits. Sink marks appear on thick sections. Warpage compromises dimensional accuracy. Tooling costs skyrocket as you increase tonnage to fill massive cavities. This is precisely where gas assist injection molding technology changes the equation.

How Gas Assist Technology Works

Gas assist injection molding introduces pressurized nitrogen gas into the mold cavity during the injection cycle. As molten plastic fills the tool, the gas creates hollow channels within thicker sections, pushing the material outward against the mold walls. This process eliminates the heavy core that would otherwise exist in solid parts, while maintaining structural integrity and surface quality.

The result? Parts that weigh significantly less, require lower clamping pressures, and exhibit superior aesthetics, all while using the same thermoplastic resins you’d specify for conventional molding.

Engineering Advantages for Complex Geometries

Gas assist technology excels at solving problems that plague large, complex parts. Consider a structural component with ribs, bosses, and varying wall sections. Conventional injection molding would likely produce visible sink marks in the thick sections of the part. Gas Assist Injection Molding eliminates this issue because the gas channel removes resin in the center of the thick sections so that the wall thickness in the thick sections are similar to the wall sections in the thin sections.

We've produced everything from heavy-duty industrial equipment housings to ergonomic medical device enclosures using this process. The technology particularly shines in applications requiring:

• Tubular or hollow cross-sections without the need for slides or complex tooling actions
• Components combining structural rigidity with weight reduction, critical in transportation and material handling applications
• Class A surface finishes on large visible components where aesthetics matter
  
  

Cost Benefits Beyond the Part

The economic advantages of gas assist extend well beyond material savings. Because the gas core reduces the volume of plastic required and lowers the clamping force needed, you can often mold larger parts on smaller, less expensive presses. A part that might require a 1,000-ton machine with conventional molding could potentially run on a 500-ton press with gas assist.

Cycle times frequently improve, as well. The gas channels facilitate more efficient cooling in thick sections, reducing the time parts spend in the tool. For low to mid-volume production runs, where tooling amortization significantly impacts piece price, these efficiencies compound into substantial cost reductions.

Tool construction costs may decrease, too. Complex parts that would require multiple slides, lifters, or loose cores can sometimes be simplified when gas channels replace solid features. This streamlined approach to tooling means faster builds and fewer potential failure points over the tool’s lifespan.

Design Considerations for Success

Gas assist molding isn’t a universal solution, but it’s remarkably versatile when applied thoughtfully. Successful implementation requires close collaboration between part designers and molding engineers from the earliest stages.

Wall thickness ratios matter significantly. The technology works best when gas channels can form in sections at least 1.5 to 2 times thicker than adjacent walls. Gas penetration length, channel diameter, and injection timing all require precise engineering to achieve optimal results.

Resin selection plays a crucial role, as well. While most thermoplastics are compatible with gas assist, engineered resins like glass-filled nylons, polycarbonates, and ABS deliver exceptional performance in structural applications. Material flow characteristics influence how uniformly the gas penetrates and how consistently hollow channels form.

Making the Technology Work for Your Application

At EnTech Plastics, we approach gas assist projects with the same engineering rigor we apply across all our advanced molding processes. Our team evaluates each design for gas assist feasibility during the quoting phase, identifying opportunities to optimize part geometry, reduce weight, and improve manufacturability.

Whether you're developing a next-generation industrial component or refining an existing design for better performance and lower cost, gas assist injection molding might be the solution that transforms complexity from a constraint into a competitive advantage.

Ready to explore whether gas assist technology fits your application? Contact our engineering team to discuss your specific requirements and discover how advanced injection molding processes can bring your most challenging designs to life.