Die-cast heat sinks and structural enclosures

Aluminum fins are routinely 1.5–2.5 mm and can be pushed to about 1.2 mm, provided three things hold: height-to-thickness no worse than about 6:1, at least 1.5° draft per side, and real venting at the tip. Pitch should stay above twice the fin thickness — any closer and the die ribs become thin, fragile and hot, which causes more trouble than the extra surface area is worth. Beyond those limits, machined or extruded fins are the better route.

It comes down to geometry and volume. Extrusion gives thinner, denser fins and better conductivity, but the section is constant along its length, so mounting holes, cavities and shaped boundaries all need secondary machining. Die casting forms a complex three-dimensional part in one shot — shell, bosses, seal groove and fins together — removing most of that machining, and the economics improve with volume. Rule of thumb: a plain bank of fins goes to extrusion; fins integrated with a housing and mounting features go to die casting.

It depends what you are optimising. For structure and cost, ADC12 — best fluidity, best value, and it suits thin complex fins. For conductivity, AlSi12 flows extremely well and conducts slightly better than ADC12. For appearance, especially coloured anodizing, A360 is low in copper and finishes far more evenly. Bear in mind that die-cast aluminum sits around 90–120 W/(m·K), well below pure aluminum: if the thermal design has no margin, extrusion or a copper base is the honest answer.

It can be improved, but there is a material ceiling. Die-cast aluminum is high in silicon, and silicon does not convert during anodizing — it stays in the film and greys it, and that cannot be fully removed. Practical improvements: switch alloy (A360's low copper and AlSi12's uniformity both beat ADC12); blast uniformly to normalise the base tone; or move to powder coating instead, which gives far more colour control. If the customer expects an extrusion-grade anodized look, powder coating is usually the honest recommendation.

In-house we do anodizing, powder coating, sand and shot blasting, vibratory finishing and PVD. Heat-sink housings usually get blasting plus powder coat, or anodizing. Plating, where needed, goes through a partner shop.

Samples and pilot runs have no MOQ; production starts at 500 pcs, and anodized cosmetic parts are best ordered as one lot so they share a bath. Before tooling we can supply metal 3D-printed, CNC-machined or simplified-tool prototypes (about 7–15 days from a simplified tool); a production tool normally takes 30–45 days to build and T1 trials 3–5 days, and finned parts should have their fill validated in simulation first; in production each batch takes 25–35 days.

Yes — we have made aluminum housings and heat sinks for energy-storage and charging equipment. As they mostly live outdoors we focus on three things: seal grooves cast in with the housing and joint faces milled to 0.05 mm per 100 mm; leak testing to the protection requirement; and in-house powder coating.