Black and dark-colored windows continue to be a major design trend in residential and commercial construction. For window and door manufacturers, however, achieving that look involves more than selecting a darker color.
The color of an exterior profile affects how it responds to solar exposure. Dark surfaces absorb more solar energy than lighter surfaces, which can result in significantly higher profile temperatures. As those temperatures rise, the thermal properties and dimensional stability of the material become increasingly important.
This creates a practical engineering question: How do you maintain the appearance customers want without compromising the long-term performance of the profile?
It is one of the challenges Engineered Profiles is addressing with mcX® multi-core extrusion technology.
Why heat matters in an extruded profile
Every thermoplastic responds to changes in temperature. As a material heats and cools, it expands and contracts. The amount of movement and the temperature at which the material begins to lose stiffness depend on the properties of that material.
In a window or door system, excessive thermal movement can contribute to problems such as bowing, distortion and dimensional instability. In demanding applications, those changes can ultimately affect how components fit and function.
Dark exterior colors make this issue particularly important because direct sunlight can substantially increase the temperature of the profile.
This doesn't mean dark profiles cannot perform well. It means material selection becomes more important as the thermal demands of the application increase.
The limitation of asking one material to do everything
Traditionally, an extruded profile is often designed around the properties of a primary material. That material may need to provide weatherability, structural performance, impact resistance, dimensional stability, appearance and manufacturability.
Those requirements do not always point to the same material.
A resin that performs particularly well in one area may provide more performance, or more cost, than is necessary in another part of the profile.
mcX takes a different approach.
mcX is a patented multi-core extrusion process that allows different materials to be placed within specific areas of a single profile. Instead of relying on one material to provide every required property, the profile can be engineered so that each material performs a particular function.
What does that look like in practice?
The layered profile shown in our mcX materials is a useful way to understand the concept.
The surface layer can be selected for properties such as UV protection and aesthetics.
The structural or impact layer can provide impact resistance and strength while helping manage material efficiency.
The core can be engineered to improve thermal stability.
These layers are produced together as a single extruded profile. The objective isn't simply to add more materials. It is to use material strategically, based on what each area of the profile actually needs to accomplish.
Why this matters for thermal performance
One of the clearest ways to understand the potential of this approach is to look at material performance under heat.
In testing presented in Engineered Profiles' current mcX technical materials, the tested mcX configuration demonstrated a heat deflection temperature of 260°F, compared with 219°F for CPVC and 167°F for PVC.
The same comparison showed 0.05% shrinkage after thermal cycling for the mcX configuration, versus 2.63% for CPVC and 3.08% for PVC. The mcX configuration also showed a CLTE of 2.35 × 10⁻⁵ in/in/°F.
Those figures require some context.
Heat deflection temperature (HDT) helps indicate how a material behaves when exposed to elevated temperatures while under load.
Coefficient of linear thermal expansion (CLTE) describes how much a material changes dimension as its temperature changes. A lower CLTE indicates less dimensional change for a given temperature change.
Thermal cycling helps evaluate how a material or profile responds to repeated temperature changes rather than a single exposure to heat.
For window and door manufacturers, these aren't simply laboratory numbers. They relate directly to a larger design goal: keeping an extruded component dimensionally stable as environmental conditions change.
Actual performance will, of course, depend on the materials, profile design and application.
mcX is not simply a “high-temperature material”
That's an important distinction.
mcX is an extrusion technology, not a single resin formulation.
Its value comes from the ability to combine materials and locate them where their properties are most useful. Depending on the application, that can allow engineers to address thermal performance alongside other requirements such as impact resistance, weatherability, complex geometry and cost.
mcX can also accommodate complex multi-channel profiles, integrated reinforcement or wire pathways, and a range of thermoplastics and engineered resins. The process is designed to scale from initial prototyping through high-volume production.
That flexibility gives product designers another option when the requirements of an application begin to exceed what a conventional single-material approach can comfortably provide.
The better question is: What does the application require?
There isn't one material solution that is right for every window or door component.
Temperature exposure, profile geometry, structural requirements, color, environmental exposure, production volume and cost all influence the right material strategy.
That's why we believe the conversation should begin with the application.
What temperatures will the profile experience? How much dimensional movement can the assembly tolerate? Where is structural strength required? Which surfaces need UV and weather resistance? And where could a different material improve performance without unnecessarily increasing material cost throughout the entire profile?
Those are the kinds of questions that determine whether a multi-core approach makes sense.
Learn More About mcX at GlassBuild America
We'll be discussing these challenges, and the engineering behind mcX, at GlassBuild America, September 23–25 in Las Vegas.
If you're attending the show, visit Engineered Profiles at Booth #3401. Bring us a profile, an application or a material challenge you're working through. Our team can talk with you about the performance requirements and whether a multi-core extrusion approach could provide an alternative to a traditional profile design.
Because the goal isn't simply to make a different extrusion.
It's to understand what the profile needs to do and engineer the materials accordingly.
Booth #3401 and let's build what's next.