Choosing the Right Material for Structural Foam & Gas Assist Molding
Material choice influences nearly every aspect of a molded part, from structural strength to cosmetic finish. For structural foam and gas assist molding, selecting the right thermoplastic is essential to getting the most from the process. Each resin behaves differently under pressure, heat, and flow conditions, which means material decisions must be grounded in performance, cost, and end-use demands.
At DeKALB Molded Plastics, we support customers in making informed choices backed by decades of process knowledge and a wide inventory of proven material options. This guide walks through the most commonly used thermoplastics in our molding operations and how each one supports successful outcomes in structural foam and gas assist applications.
Why Material Selection Impacts Performance
Thermoplastics molded through structural foam and gas assist processes often need to handle mechanical loads, resist environmental exposure, or maintain tight tolerances across complex part geometries. The nature of low-pressure molding allows for larger parts, reduced internal stress, and thinner wall sections, but it also requires materials that flow and fill predictably.
Material properties such as impact resistance, flexural strength, thermal stability, and chemical resistance all come into play. Matching the material to the part’s intended function early in the development process leads to fewer revisions, shorter lead times, and a better-performing product.
Common Thermoplastics Used at DeKALB
DeKALB offers a wide range of both commodity and engineering-grade resins. These are the most frequently used materials in our structural foam and gas assist programs:
High Density Polyethylene (HDPE)
A reliable choice for industrial applications, HDPE offers strong impact resistance and excellent moisture and chemical tolerance. It is especially useful for outdoor or heavy-duty parts such as plastic pallets and safety enclosures.
Polypropylene (PP)
Lightweight and fatigue-resistant, polypropylene is a versatile resin well-suited for components that require repeat flexing or exposure to a wide range of conditions. It is commonly used in automotive, consumer, and specialty handling applications.
Noryl (PPO)
Known for its thermal stability and flame-retardant properties, Noryl is often selected for enclosures, electronic housings, and parts requiring low moisture absorption. It also maintains dimensional accuracy over time, even under challenging conditions.
Polycarbonate (PC)
With high impact strength and clarity, polycarbonate is suitable for applications where both toughness and visual appearance matter. It handles stress well and retains performance under a range of environmental conditions.
ABS and PC/ABS Blends
ABS offers a balanced combination of toughness, moldability, and affordability. When blended with polycarbonate, the material gains additional heat resistance and impact strength, making it a strong fit for housings, structural panels, and components requiring a clean finish.
Polystyrene Options (FRPS, GPPS, HIPS)
Flame retardant polystyrene (FRPS) is often used in electrical and low-heat environments where regulatory compliance is needed. General purpose polystyrene (GPPS) offers rigidity and clarity, while high impact polystyrene (HIPS) introduces greater toughness for more demanding use cases. These materials are often chosen for non-structural parts or those where appearance and cost are primary factors.
Boosting Performance with Fillers and Reinforcements
Thermoplastics can be customized further with additives. At DeKALB, we incorporate the following reinforcements to modify material behavior for specific applications:
- Glass Fiber: Improves stiffness, tensile strength, and dimensional stability, especially in structural parts.
- Carbon Fiber: Offers similar benefits to glass fiber but at a lighter weight, useful in performance-driven designs.
- Glass Bead: Enhances surface finish and flow characteristics, supporting tighter tolerances and better appearance.
- Rubber: Adds elasticity and impact absorption, often used to improve flexibility in parts exposed to vibration or dynamic loads.
- Impact Modifiers: Improve toughness and resistance to cracking, helping parts withstand sudden loads or harsh handling conditions.
These additives allow us to fine-tune material performance to better match your part’s functional and environmental requirements.
Material Matching Through Engineering Collaboration
Choosing a resin based solely on datasheets can lead to surprises on the production floor. That’s why we collaborate closely with customers to evaluate the full picture, including end-use conditions, appearance goals, processing constraints, and budget.
Our engineering support includes:
- Part design review
- CAD and mold flow analysis
- Finite element analysis (FEA)
- Tooling and project optimization
We explore trade-offs across different material options and recommend resins that align with your performance expectations and production realities. The result is a molded part that performs reliably without adding unnecessary cost.
Why Material Flexibility Matters for Structural Foam and Gas Assist Molding
Both structural foam and gas assist molding benefit from resins that support lightweight, rigid, and dimensionally stable parts. Structural foam molding creates parts with a solid outer skin and a foamed cellular core, improving rigidity while cutting weight by up to 20% compared to solid molded parts. Gas assist molding uses nitrogen to form hollow channels within thick sections, which reduces cooling time, improves aesthetics, and supports variable wall thicknesses within a single part.
These molding techniques excel when paired with materials that support partial fill methods, form tight skins, and manage internal pressure without warping or shrinking. Having access to a wide variety of thermoplastics – each with different performance characteristics – gives us the flexibility to mold complex geometries without compromising the function or integrity of the final part.
Partnering with DeKALB for Material Confidence
Selecting the right material isn’t always straightforward. When timelines are tight and specifications are complex, it helps to work with a team that knows how to ask the right questions and has the tools to find the right answers.
For more than four decades, DeKALB Molded Plastics has helped manufacturers across industries select and mold the right thermoplastic materials for the job. We combine process knowledge, deep material expertise, and custom molding capabilities to support product launches with fewer delays and better results.
Let us help you explore what’s possible with structural foam and gas assist molding, starting with the right material – contact us today!