Choosing between extruded, die-cast and skived heat sinks is not a question of which technology is best — it is a question of which one matches your fin geometry, your volume and the flatness your interface can tolerate. Get that wrong in either direction: pay for tooling you cannot amortise, or accept thermal performance your design cannot spare.
How Each Process Works
Extrusion pushes a heated aluminium billet through a steel die, producing a profile with a constant cross-section. Fins, channels and mounting rails are formed in a single pass and run the full length of the bar, which is then cut to the length you specify. The alloy is normally 6063 or 6061.
Die casting injects molten alloy — typically ADC12 or A380 — into a steel mould. Because the shape is cast rather than pushed, it can carry bosses, stepped bases, integrated mounting holes and geometry that changes along the part.
Skiving takes a solid aluminium block and shaves fins out of it with a blade, lifting each fin out of the parent metal. Nothing is bonded or welded, so the fin-to-base joint has no thermal interface — and because the blade can take very fine cuts, skived parts reach fin densities the other two processes cannot.
Thermal Performance Compared
The alloy decides more than the process name suggests. Extruded 6063 conducts at roughly 200 W/m·K. Cast ADC12 sits near 96 W/m·K — less than half. For the same footprint an extruded heat sink therefore spreads heat into the fins faster, and a skived part does better again because there is no interface loss between fin and base.
For a given envelope, the usual thermal ranking is skived, then extruded, then die-cast — before accounting for the fin density each process can actually hold.
Tooling Cost and Minimum Order Quantity
Extrusion dies are comparatively inexpensive and quick to make, and one die can serve several lengths or several customers, so the minimum order is usually set by the die rather than by the part. Die-casting moulds cost substantially more and take longer to bring on stream, which only pays back once annual volume is high. Skiving needs no die at all — the cost sits in machining time, which is why skived heat sinks are common in small, high-value batches and rare in high-volume consumer products.
Where Each Process Wins
- Extruded — LED and power-electronics heat sinks, motor housings, enclosures, T-slot framing and every part with a constant cross-section. The best balance of cost, thermal performance and lead time.
- Die-cast — parts where the geometry is the problem: integrated bosses, mounting features, tapered sections or a shape you do not want to machine afterwards.
- Skived — compact, high-power-density cooling where fin count and fin thickness are the limit, such as IGBT and CPU cooling in smaller volumes.
Specifying an Extruded Heat Sink
If extrusion is the right answer, five numbers decide the outcome: fin height, fin thickness, fin pitch, base thickness and overall length. Thin, closely spaced fins cool better but are harder to fill, so the die has to be designed around the fin ratio rather than the other way round. Send the drawing together with the duty point — heat load, airflow and ambient — and the fin geometry can be checked for both thermal performance and extrudability before any tooling is cut.
Send us your drawing and target spec and we will reply with a quote and die feasibility within 24 hours.
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