Thermal Pour & Debridge
The main function of a thermal break system is to separate an aluminum profile into two parts to reduce thermal conductivity in a window. The two ways of doing this are by using poured polyurethane or polyamide insulating strips.
Aluminum is a highly thermal conductive material that will rapidly transfer exterior climatic temperature unless something is done to stop the thermal conduction. A thermal barrier system will improve thermal performance while maintaining the structural and long-term durability of the fenestration unit.
When considering structural longevity, wind loads in high rise buildings and in curtain wall applications, composite materials that perform both efficiently and structurally are demanded. Thermal barriers are true structural insulators that maintain an extremely high shear modulus for windloads.Polyurethane's pour and debridge systems are formulated for these exacting applications, and according to the manufacturer Azon, offer up to four times more shear strength than that of polyamide.
Prepare, Pour and Debridge
The three-step pour and debridge process, which includes a mechanical lock by either the Azo-Brader or Lancer method, results in an energy-saving window frame with the advantage of long-term durability that is warranted from structural deterioration.
An aluminum profile is designed and extruded with a strategically placed cavity to limit the bridge of metal that acts as a conductor of hot or cold temperatures on the exposed surface. The cavity surface is conditioned with a lanced, mechanical lock prior to the application of the liquid polyurethane polymer into the channel. The insulating two-part polyurethane solidifies into a very strong, low conductance structural polymer. And finally, the third and final step in the thermal barrier process—is the removal of the metal bridge from the bottom of the channel creating an aluminum-polymer composite with high shear strength capable of withstanding strains and forces in extreme weathering conditions.
Design. An aluminum window profile is designed and extruded with a strategically placed channel to encapsulate the Azon insulating polymer.The channel surface can be conditioned using the patented Azon Azo-Brader™ by abrading the profile to mechanically lock the polyurethane polymer with the finished surface of the aluminum profile.
Pour. Utilizing the Azon Fillameter™ equipment, two-component polyurethane is dispensed as a liquid into the thermal barrier channel.Within minutes, the thermal core, consisting of a reactive resin and a polymeric isocyanate, react and solidify quickly into a very strong, structural and insulating polymer.
Debridge. Extrusions are transported to the Azon Bridgemill™ for the third step in the process, removal of the metal bridge from the bottom of the channel to produce a true, non metal-to-metal structural thermal barrier.Linetec also has skip debridging and double debridging capabilities.
Skip debridge leaves a small aluminum bridge remaining across the thermal cavity. This enhances structural integrity but does sacrifice some thermal performance. Typically one inch of aluminum bridge remains every foot along the extrusion. Other ratios can be specified.
Double debridge is often required to minimize extrusion costs. It is also available for double fill cavities when increased structural strength and stability is required.
How Thermal Barrier Systems Can Improve Aluminum WindowsEnergy costs rank among the top concerns for building owners and managers, while comfort and indoor temperature control head occupants' top concerns.
Read Linetec's article on improving the thermal performance and influencing long-term savings on the life of your building.
Material Size & Cavity Guidelines
- Extrusions must be 6' or longer to be debridged
- Radius material can be poured by Linetec, but not easily debridged
- Thermal fill cavity must be symmetrical to be abraded
- The opening of the fill cavity must be obstruction-free for the profile to be abraded
- There must be at least 1/8" clearance beyond each of the lugs for the profile to be abraded