CNC Machined Heat Sinks
When an extruded heat sink can't hit the fin geometry or base flatness a design needs, it gets machined. We CNC machine aluminum and copper heat sinks with high fin density and a flat, smooth contact base for power electronics and high-heat applications.
What is a CNC machined heat sinks?
A heat sink dissipates heat from a component (a processor, power transistor, LED, or laser) into the air through an array of fins. CNC machining is used over extrusion when the fins must be taller, thinner, or denser than an extrusion die allows, when the base needs precise flatness for low thermal contact resistance, or for copper sinks (which can't be extruded into fins economically). Base flatness and surface finish at the contact area drive thermal performance.
Common materials
The standard — good thermal conductivity, light, and inexpensive to machine.
~60% higher conductivity than aluminum for the highest heat-flux applications, at higher weight and cost.
Typical tolerance
±0.05 mm (base flatness tighter)
Base flatness (often 0.05 mm or better, Ra 0.8 µm) at the component contact area is the performance-critical feature; fin dimensions are less critical.
How we machine them
Slots the fin array and machines the base in aluminum or copper.
Surface grinding / fly-cutting
Achieves the flat, smooth contact base needed for low thermal resistance.
Black anodize on aluminum slightly improves radiative cooling and corrosion resistance.
Design tips that lower cost
Don't over-specify fin thinness
Very thin, tall fins (high aspect ratio) chatter and bend during milling, driving cost up. Work with us on a fin thickness that the cutter can hold rigidly while still meeting the thermal target.
Prioritize base flatness over everything
Thermal contact resistance is dominated by base flatness and finish at the contact patch. Spec flatness and Ra on that face — it matters far more than fin tolerances.
Consider copper only where it's worth it
Copper conducts heat much better but is heavier, pricier, and harder to machine. Use it for concentrated high-flux sources; aluminum is the right call for most sinks.
Leave wall thickness under thin fins
Keep the base under the fins thick enough to spread heat — a base that's too thin creates hot spots regardless of fin area.
Industries we machine heat sinks for
Heat Sinks — frequently asked
Aluminum or copper for a CNC machined heat sink?
Aluminum 6061/6063 for most applications — light, cheap, good conductor. Copper only where heat flux is extreme and the added weight and cost are justified; copper conducts roughly 60% better than aluminum.
How flat can you machine the heat sink base?
We achieve base flatness of 0.05 mm and better with fly-cutting or grinding, plus a fine surface finish — both critical for low thermal contact resistance.
Can you machine high-fin-density heat sinks?
Yes — CNC machining reaches fin geometries an extrusion die can't. There's a practical limit set by fin rigidity during cutting; share your target and we'll confirm what's machinable.
Need heat sinks machined?
Upload your drawing — our engineers review it for DFM and send a real quote within 24 hours. No minimum order.
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