The Rheocasting Revolution in LED Housings

Importing LED housings into the European Union is about to become significantly more complicated and costly due to the Carbon Border Adjustment Mechanism (CBAM). When the transition phase ends on 1 January 2026, importers will be required to purchase CBAM certificates at a price aligned with the EU Emissions Trading System (ETS) allowance, currently around €70–75 per t-CO₂. Although a draft May 2025 amendment would spare very small consignments and postpone full trading to 2027, more than 90 % of import emissions will still be captured.

Why today’s heat sinks fall short

For makers of LED fixtures, the aluminium heat sink is the single largest contributor to both product weight and embedded carbon. It must also dissipate increasingly severe thermal loads: high-power LEDs can push peak temperatures beyond 120 °C, shortening their lifetime if heat is not transported away. Yet, conventional high-pressure die-casting alloys conduct only approximately 100–130 W/m·K, which is barely half that of pure aluminium, and struggle to cast the very thin, tall fins designers now need.

Thin fins maximise surface area and create turbulent airflow, but the alloy must still carry heat rapidly from the LED board into those fins. With HPDC alloys, the usual trade-off is harsh: lower silicon (for better conductivity) means poor castability, while higher silicon (for fillability) means poor conductivity. Either way, cooling performance plateaus and fixture makers compensate with bigger, heavier housings, precisely the sort of material inefficiency that CBAM penalises.

Rheocasting: One Process, Three Wins

Enter Comptech Rheocasting, which utilises a high-solid-fraction (30 to 45%) slurry. Three things change at once:

1. Castability with low-Si alloys:

Rheocasting tolerates 1.8–3.5 % Si, which is close to wrought 6000-series chemistries, yet still fills high-aspect-ratio fins.

2. Thermal conductivity jump:

Those low-Si chemistries, combined with a globular α-Al microstructure, deliver a thermal conductivity of ≥180 W/m·K at 100 °C while still meeting the modest 80 MPa yield-strength requirement.

3. Near-net-shape freedom:

Fins can be thinner, taller, and even angled for forced-air turbulence without requiring secondary machining.

The Sustainability Dividend

Rheocasting’s preferred alloy for this application is marketed as Rheocool and is made entirely from post-consumer scrap. Because this secondary aluminium carries a 0 kg CO₂-eq/kg Al burden at the scrap gate, switching from primary metal (4 to 20 kg CO₂-eq/kg Al) to recycled feedstock reduces the embodied carbon upfront. Lower silicon content matters doubly: it lifts thermal conductivity and removes one of the most carbon-intensive alloying additions.

From a CBAM standpoint, every tonne of CO₂ you avoid in production is a tonne you do not have to cover with certificates. At current ETS prices, a 30% reduction in carbon footprint on a typical 4kg aluminium heat sink can trim €8–10 off the import tax, multiplied across thousands of fixtures per shipment.

For luminaire brands selling into Europe, the message is simple: switch now to low-carbon rheocasting heat sinks and stay ahead of both performance curves, thermal and regulatory.

Learn in the Rheocasting Workshop from Casting-Campus GmbH how to utilise Rheocasting for your product portfolio. Schedule your Free Consultation Call today. You find the booking tool right below this post.