The 70% Problem: LEDs Are Heat Machines
Only about 30% of the electricity entering an LED becomes light; the remaining 70% becomes heat. If that heat cannot escape, the junction temperature climbs — and for every 10°C rise, LED lumen output and rated lifetime (L70/L90) drop noticeably. Thermal management is therefore the single biggest factor in how long your luminaire actually lasts.
Why Extruded Aluminium Is the Default
Aluminium 6063-T5 combines a thermal conductivity of around 200 W/m·K, low weight and natural corrosion resistance. Extrusion produces dense fin arrays and thin walls in a single pass — maximising surface area for convection while keeping tooling cost low at production volume. That is why the vast majority of commercial LED heat sinks are extruded profiles rather than cast or stamped parts.
Common Heat Sink Geometries for LED Fixtures
Sunflower/radial fin profiles for high-power street and industrial lamps, plate-fin profiles for linear and panel luminaires, and integrated housing designs where the profile is the lamp body itself. An anodized finish improves surface emissivity — helping the sink radiate heat as well as convect it — and provides the corrosion protection outdoor fixtures need.
Specifying a Heat Sink for Your Luminaire
Share three numbers with your supplier: LED wattage, maximum allowable junction temperature, and ambient operating temperature. From these we size the profile, fin spacing and surface area. For OEM programmes, a custom die is amortised quickly across production volume — Siken Aluminum supplies extruded LED heat sink profiles to lighting manufacturers worldwide, from prototype to container scale.