Circular Sunflower Heat Sink

A circular sunflower heat sink is a 6063 aluminum extrusion with a hollow center bore and dense radial fins that radiate outward like the rays of the sun — giving it the "sunflower" name in the trade.

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Product Introduction

A circular sunflower heat sink is a 6063 aluminum extrusion with a hollow center bore and dense radial fins that radiate outward like the rays of the sun - giving it the "sunflower" name in the trade. The round body wraps around cylindrical power devices (high-power LEDs, servo motors, power modules, tubes), and the 360° fin array carries heat away by natural or forced convection in any orientation. We build these radial fin heat sinks to your outer diameter, bore size, fin density, and cut length.

- Hollow center bore - the device drops straight through; no bracket, no offset, short thermal path from source to fins
- 360° radial fins - convective surface on every side, so orientation and cross-flow direction barely matter
- One-piece 6063 extrusion - no bonded fins, no weld, light and cost-effective with high repeatability
- Fully customizable - outer diameter, inner bore, fin pitch/density, and cut length all to your drawing

Extruded Circular Sunflower Heat Sinks

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Why a Round Sunflower Profile for Round Devices

A circular sunflower heat sink solves a geometry problem other coolers create: most power devices that fail thermally are cylindrical - high-power LED COB arrays, servo-motor ends, power transistors, IGBT tubes, and sealed modules. A flat parallel-fin cooler forces you to clamp a round source onto a flat plate with a bracket, adding interface resistance and assembly steps. The radial cooler puts the source in the center bore so heat spreads outward uniformly into fins on every side.

Because the fins radiate in all directions, convection is nearly independent of orientation and cross-flow direction. In a sealed drum, a rotating motor, or a round luminaire housing, the round aluminum heat sink keeps working whether the airflow comes from one side or swirls around. That makes it the natural choice for omnidirectional cooling where a directional flat cooler would overheat on its blind side.

Engineering note for buyers: Send the device outer diameter, total dissipation (W), ambient temperature, available envelope (outer diameter and length), and whether cooling is natural or forced-air. We size the bore, fin height, fin density, and cut length, then return a case- or surface-temperature estimate and margin before tooling.

Product Overview

Three angles of the same radial cooler - the top view showing the sunflower fin pattern, a side section of the hollow tube wall and fins, and a mounted view with a cylindrical device dropped into the bore.

Top view

Radial fins radiating from a hollow center bore - the "sunflower" pattern.

Side section

Hollow tube wall with radial fins attached on the outside; device sits inside the bore.

Mounted

Cylindrical device (LED, motor, tube) drops into the center; fins radiate around it.

Why Buyers Specify Our Water Cooled Heat Sinks

Fewer Parts, Lower Landed Cost

The hollow bore replaces the bracket and flat-plate interface other coolers need. One round extrusion instead of a cooler plus a mounting kit - fewer line items, simpler reordering.

For Procurement Teams

Sized to Your Device, Not a Guess

We match bore, fin height, fin density, and cut length to your cylindrical source and airflow, then return a surface-temperature estimate so you confirm margin before sign-off.

For Thermal & Mechanical Engineers

Drop-in Round Form Factor

LED modules, servo-motor ends, and power tubes seat straight into the bore. The 360° fins keep cooling even when the assembly rotates or airflow swirls.

For Luminaire / Motor OEMs

Stock & Private Label

Common outer-diameter / bore combinations kept in neutral or branded stock, with tiered pricing for recurring round-cooler programs across lighting and motion customers.

For Distributors

Technical Specifications

Reference radial fin heat sink build. Outer diameter, bore, fin density, and length are set to your device and envelope.

Parameter	Specification
Base Material	Aluminum 6063-T5 (default); 6061-T6 on request
Profile Type	Circular radial-fin extrusion with hollow center bore ("sunflower")
Outer Diameter (OD)	40-250mm typical; custom per envelope
Center Bore	Custom to device outer diameter (e.g., 10-120mm);tolerance ±0.1mm
Fin Height (radial)	8-60 mm; matched to OD and airflow
Fin Density / Pitch	Custom fin count and pitch; tighter for forced air, wider for dusty or passive
Cut Length	20-300 mm typical; saw cut to drawing
Wall / Base Thickness	Set so bore seats the device without flex; thicker for high power
Surface Finish	~0.4–3.0 °C/W depending on OD, fin density, and airflow
Cooling Method	Natural convection (omni-directional) or forced-air
Certifications	RoHS, REACH compliant; ISO 9001 manufacturing

Circular Sunflower Heat Sink Selection Guide

Match the round cooler to your cylindrical device, power, and cooling condition.

Device/Application	Typical Power	Recommended Round Build
High-power LED lamp/COB array	50-300 W	Hollow bore for LED module, natural-convection tall radial fins, black anodize
Servo/stepper motor end	50-500 W	Bore to motor shaft-end diameter, forced or natural, concentricity-critical
Power module/transistor in tube	30-400 W	Bore to device body, dense fins, forced-air for sealed cabinets
Inverter / converter round stage	100-600 W	Larger OD, dense radial fins, forced cross-flow fan
Industrial round power module	100-400 W	Mid OD, wider fin pitch for dusty shop air
Compact sealed enclosure device	Any	Black anodize for emissivity; fin density tuned to available height

Technical Differences: Radial Fin vs Other Cooler Forms

A circular sunflower heat sink is one of several fin geometries. Picking the wrong one either wastes the round advantage (a flat cooler clamped to a round device) or over-spends (a liquid cold plate for a passively-cooled LED). Here is how the common forms compare for cylindrical and omnidirectional loads.

Form	Best For	Limit	Relative Cost
Radial / sunflower fin (this page)	Cylindrical devices, omni-directional or rotating cooling	Needs round envelope; less directed airflow	Low-Med
Parallel / straight fin	Flat IGBT, power modules, directed forced air	Poor for round sources without a bracket	Low
Pin fin	Omni-directional but square footprint, high flux	Higher pressure drop; harder to extrude round	Medium
Skived fin	Highest flux density, compact, flat base	Not a round-form part; higher cost	Medium-High
Heat-pipe / liquid cold plate	Extreme density or sealed remote cooling	Far higher cost and complexity	High

Rule of thumb: If your heat source is round or the assembly rotates / sits in swirling air, a radial fin heat sink with a hollow bore is usually the lowest-cost, cleanest solution. Choose a parallel-fin cooler when the device is flat and airflow is directed; move to skived or liquid cooling only when flux density exceeds what fins can handle.

Material & Fluid Comparison: 6063 vs 6061 vs Copper vs Die-Cast

The body material trades weight, cost, and conductivity. For most round coolers, extruded 6063 aluminum is the right call; copper is rarely justified and die-cast trades conductivity for shape freedom.

Material	Thermal Conductivity	Density	Cost	When to Use
Aluminum 6063-T5	~209 W/m·K	2.70 g/cm³	Low	Default for radial extruded sunflower coolers
Aluminum 6061-T6	~167 W/m·K	2.70 g/cm³	Low-Med	When higher stiffness / strength is needed
Copper (C1100)	~398 W/m·K	8.96 g/cm³	High	Interface plates only; almost never the whole round body
Die-cast aluminum (ADC12)	~96 W/m·K	2.66 g/cm³	Medium	Complex non-extrudable shapes; lower conductivity

Recommendation: Specify 6063-T5 for the bulk of your circular sunflower heat sink program - it extrudes cleanly into the radial profile, is light, and carries the typical case-to-air load at the lowest landed cost. Use 6061-T6 only when mechanical stiffness at the bore matters. Reserve copper for a thin interface insert, and avoid die-cast unless the shape cannot be extruded (its lower conductivity hurts fin performance).

Application

High-Power LED Lighting

COB arrays, flood, stadium, and grow lamps where the LED module drops into the bore and 360° fins cool passively.

Servo & Stepper Motors

Motor end-bells and brake resistors; the bore matches the shaft end, cooling holds while the motor turns.

Power Modules & Tubes

Transistors, rectifiers, and sealed power modules in a cylindrical package.

Inverters & Converters

Round-stage power devices in solar, energy-storage, and frequency inverters needing omni-directional fins.

Industrial Equipment

Round power modules on machinery where airflow direction is unpredictable.

Sealed / Rotating Assemblies

Drum housings, rotating joints, and sealed luminaires where orientation-independent cooling matters.

Manufacturing Process

From aluminum bar to a finished, device-ready radial cooler.

Extruded

6063 bar, radial fins+bore

Cut to Length

Sawn to your spec

CNC (opt.)

Counterbore, thread, flat

Anodize(opt.)

Natural or black

Deburr & Clean

Assembly-ready

Inspect

Bore, OD, finish

Quality Inspection (Testing & QC)

Every circular sunflower heat sink ships against an inspection plan tied to your device's bore fit and cooling requirement. Round-form QC focuses on the points that actually affect fit and thermal contact.

Inspection Point	Method	Acceptance
Incoming material	Mill cert+spectrometer spot check	6063/6061 per order; no off-grade alloy
Bore diameter & concentricity	CMM / bore gauge, runout check	Bore ±0.1 mm; concentric to OD within 0.15 mm
Outer diameter & roundness	CMM/ ring gauge	Per drawing, roundness within 0.1 mm
Fin straightness & density	Visual + gauge	No bent fins; pitch per drawing
Anodizing thickness	Eddy-current coating guauge	8–15 µm typical; logged per batch
Thermal resistance (sample)	Bench test vs device simulation	Within quoted Rθ margin (report attached)
Visual & burr	100% visual, deburr check	No sharp edge, no finish defect
CoC/traceability	Batch record	Material cert, inspection report, RoHS/REACH

For buyers: Ask for the batch inspection report and material certificate with your first order - we issue a Certificate of Conformity (CoC) and can supply PPAP-level documentation for automotive or grid programs on request, including the bore concentricity record that matters most for round coolers.

Cost Factors

What drives the price of a radial fin heat sink - and how to specify one that meets the thermal budget without paying for unused capability.

Factor	Effect on Cost	Buyer Tip
Material	6063 < 6061 < die-cast < copper-insert	Stay 6063 unless bore stiffness forces 6061
Outer diameter & fin height	More aluminum = higher unit cost	Size to real envelope, not worst-case
Bore size & tolerance	Tight concentricity adds inspection	Specify the tolerance you truly need
Fin density	Denser fins=more extrusion mass	Match pitch to airflow; don't over-fin
CNC machining	Counterbores, threads, flats add setup	Reuse a standard bore where possible
Anodizing	Black anodize adds a step	Natural finish is fine unless emissivity matters
Tooling / NRE	One-time for new radial die	Amortize across volume; ask about shared dies
Order quantity	Volume pricing at 1,000+	Prototype MOQ is low; lock volume price early
Logistics	FOB vs DDP; carton vs crate	DDP simplifies import; consolidated shipments save freight

Budget guidance: For a typical round LED or motor cooler, a 6063 extruded radial profile with standard bore is the lowest landed cost. Keep die-cast off the table unless the shape cannot be extruded (its lower conductivity hurts fin performance), and specify natural (not black) anodizing unless emissivity is a real factor.

Customize Process

From your device drawing to a finished, drop-in radial cooler. A typical circular sunflower heat sink program runs in seven steps.

RFQ

Device OD, power, airflow, envelope

DFM Review

We check bore, OD, fin feasibility

Quote & Thermal Est.

Profile, R, temp margin, price

Sample

CNC-modified or new-die sample, 5-10 days

Mass Production

Extrud, cut, machine, finish, inspect

QC & Docs

Report, CoC, material cert, RoHS/REACH

For modified standard radial profiles we skip the new-die step, so samples can ship in 5–7 working days. Full custom extrusions add tooling lead time, which we confirm in the quote.

What Customers Say

"We replaced a flat-bar heat sink on a 200 W round LED flood with their circular sunflower heat sink. The hollow bore let the LED module drop straight in, and the radial fins dropped case temperature by 14°C with no fan. Exactly the round-form factor our luminaire needed."

R. Castillo

Lighting Engineer, Mexico

"Our servo motor ran hot in a sealed drum housing. Their radial-fin cooler with a custom bore seated the motor shaft end perfectly, and the 360° fins worked with our cross-flow fan. Concentricity report shipped with the first batch - clean."

K. Nowak

Mechanical Engineer, Poland

"For a round power module in a rotating assembly, the sunflower profile saved us a bracket and a flat-plate interface. One part instead of three, and the inspection report with every batch keeps our QA happy."

T. Abebe

Procurement, Ethiopia

FAQ

Q: What is a circular sunflower heat sink used for?

A: A circular sunflower heat sink cools cylindrical power devices - high-power LEDs, servo/stepper motors, power transistors, tubes, and round power modules. The hollow center bore lets the device sit inside the cooler, and the 360° radial fins carry heat away by natural or forced convection in any orientation. If your heat source is round or the assembly rotates, this form beats a flat cooler.

Q: Radial fin vs parallel fin - which should I pick?

A: Pick a radial fin heat sink (sunflower) when the device is cylindrical, the assembly rotates, or airflow swirls from any direction - the 360° fins cool regardless of orientation. Pick a parallel/straight-fin cooler when the device is flat (IGBT base, power module) and airflow is directed. See our technical-differences section above.

Q: Can you customize the bore and outer diameter?

A: Yes. The bore is cut to your device outer diameter with ±0.1 mm tolerance and held concentric to the OD within 0.15 mm; outer diameter, fin height, fin density, and cut length are all set to your drawing. We can also add counterbores, threads, or flats by CNC.

Q: How do you size the cooler to my device?

A: Send the device outer diameter, total dissipation in watts, ambient temperature, available envelope (OD and length), and whether cooling is natural or forced-air. We match bore, fin height, fin density, and length, then return a surface-temperature estimate and margin before tooling.

Q: What quality documents do you provide?

A: Every batch ships with a material certificate, inspection report (bore concentricity, OD/roundness, fin density, anodizing thickness, sample Rθ), and RoHS/REACH statement. We also issue a Certificate of Conformity, and can supply PPAP-level documentation for automotive or grid programs on request.

Q: What is the MOQ and lead time?

A: Modified-profile radial samples ship in 5–7 working days with a low prototype MOQ. New extrusions add tooling lead time, confirmed in the quote. Volume repeats run on a scheduled basis with tiered pricing for 1,000+ programs.

Q: Aluminum or copper for the round body?

A: For the whole round body, extruded 6063 aluminum is almost always right - it is light, low-cost, and carries the typical case-to-air load. Copper is ~3× the cost and weight for a small gain, so we reserve it for a thin interface insert at the hottest spot, not the entire sunflower cooler.