Three Ways to Make a Heat Sink
Almost every aluminium heat sink on the market is made one of three ways: extrusion, die-casting or stamping. Extrusion pushes a heated billet through a steel die to form long profiles with dense fins – the backbone of LED, power electronics and telecom cooling. Die-casting injects molten aluminium into a mould, producing complex three-dimensional shapes in one piece – ideal for integrated housings. Stamping blanks and bends thin aluminium sheet, the cheapest route for simple flat plates. The right choice depends on four things: heat load, geometry, volume and budget – and getting it wrong costs money twice, once in tooling and once in thermal performance.
Extrusion Wins on Fin Density and Cost per Watt
For pure thermal performance per dollar, extrusion has no rival. Fins as thin as 0.8 mm with high aspect ratios – exactly what thermal engineers want – are routine for extrusion dies, while die-casting struggles below 1.5-2 mm walls and stamping cannot make fins at all. Extruded profiles also scale in length: the same die can run a 100 mm part today and a 3,000 mm part tomorrow, which is why long heat sinks for busbars, railway traction and solar frames only make sense as extrusions. Tooling is dramatically cheaper too: an extrusion die can cost a fraction of a comparable die-cast mould, and thermal conductivity stays uniform because the material is wrought, not cast.
When Die-Casting and Stamping Make Sense
Die-casting earns its higher tooling cost when the heat sink must also be a structural part: motor housings, LED streetlight bodies, inverter enclosures with integrated fin arrays, or automotive parts needing brackets and bosses in one casting. At high volumes the per-part cost falls below extruded-plus-machined alternatives, and the mould can reproduce complex mounting features no extrusion can. Stamping is the budget option for simple flat or corrugated plates – think LED panel backplates or low-power aluminium covers – where a 2-3 mm sheet with a stamped pattern removes enough heat for the application, and volumes justify the modest tooling. Neither can match extruded fin density; they win on integration and unit cost, not on thermal efficiency.
A Simple Decision Framework
Start with the thermal requirement. If you need tall thin fins or long profile lengths, extrusion is the answer and the decision ends there. If the part is compact, three-dimensional and needed at high volume – an integrated housing, a motor frame – evaluate die-casting despite the tooling. If the heat load is low and the shape is a flat plate, stamping may be the cheapest acceptable solution. Many real products use combinations: an extruded heat sink CNC-machined into a cold plate, or an extruded core bonded into a die-cast frame. At Siken Aluminum we extrude, machine and anodise under one roof, and our engineers can compare all three routes against your drawings – with realistic tooling and unit cost numbers – before you commit.