Matching Thermal Behavior of Aluminum & Polyamide in Thermal-Break Systems

Thermal-break systems rely on the precise integration of aluminum and polyamide components to achieve both structural strength and superior insulation. However, aluminum and polyamide have significantly different coefficients of thermal expansion (CTE), which can lead to thermal stress, deformation, or system failure if not properly managed. Understanding this mismatch and engineering solutions around it is essential for developing long-lasting, high-performance thermal-break profiles.

1. The Thermal Mismatch Challenge

Aluminum expands at approximately 23×10⁻⁶ 1/K, while PA66 GF25 typically expands between 8–12×10⁻⁶ 1/K. This difference means that under temperature fluctuations, aluminum elongates more than polyamide. If not compensated through design, this can cause bending, micro-gaps, or shear stress at the interface, leading to reduced insulation and structural performance.

2. Role of PA66 GF25 in Reducing Thermal Distortion

The high stiffness of PA66 GF25 helps stabilize the structure and reduce thermal distortion. Reinforcement with glass fiber provides greater dimensional stability, ensuring that the polyamide component remains structurally reliable even when the aluminum frame expands or contracts. This balanced behavior is crucial for maintaining integrity in façade systems.

3. Symmetrical Profile Design

One of the most effective engineering solutions is designing profiles with symmetrical geometry. Symmetry distributes stress evenly across both sides of the thermal-break assembly, preventing twisting or warpage. Balanced wall thicknesses and controlled material flow during extrusion further enhance the stability of the final product.

4. Mechanical Interlocking & Enhanced Bonding

Thermal-break bars often incorporate teeth, grooves, or mechanical interlocks that improve the connection between aluminum and polyamide. These features enhance load transfer, reduce shear stress, and prevent sliding or disengagement during thermal expansion. Combined with precise extrusion tolerances, these interlocking mechanisms significantly extend the lifespan of the system.

Conclusion

Managing the thermal expansion mismatch between aluminum and polyamide is essential for producing durable, efficient thermal-break systems. With high stiffness, proper geometric design, and mechanical interlocking, PA66 GF25 ensures long-term stability, structural integrity, and consistent insulation performance—even under severe temperature fluctuations.