LED Lighting: An Integrated Heat-Sink Housing, Extruded as One Part
A leading lighting brand was assembling every fixture from a housing plus a bolted-on heat sink. Two parts, a thermal interface and a second supplier — for a linear profile that could carry the fins itself.
- Industry
- LED lighting
- Process
- Extrusion + CNC + bead blast anodize
- Alloy
- 6063-T5
- Key spec
- Section ±0.05 mm, fins 3–6 mm pitch
What the customer needed
The customer needed a linear fixture housing that also acted as the heat sink. The existing design used a plain extruded body with a separate finned heat sink bolted to the back, with thermal paste between them.
The constraint was flatness across the LED board channel: the board had to sit on the housing with a consistent thermal path along the full length, which meant the section could not wander more than ±0.05 mm from nominal across the run. A bolted-on heat sink also introduced a second part to inventory and a second tolerance to stack.
The question was whether a single extrusion could carry a high fin-to-gap ratio and still hold the board channel flat over the length of the fixture.
Constraints that decided the part
- Section tolerance ±0.05 mm across the full length
- Fins integrated in the body, 3–6 mm pitch
- Board channel flat enough for a consistent thermal path
- Visible face free of die lines after anodizing
- Alloy 6063-T5 for thermal conductivity and anodizing
How the part was made
The same route we would propose today, in the order it actually runs.
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Section design
The fin array, the board channel and the visible face were laid out in one section, with the parting line placed on a hidden edge so die lines would not land on the customer-facing surface.
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Die manufacture — 4–5 days
The die was cut with a feeder design matched to the fin ratio. This is the stage that decides whether the fin tips fill completely or come out rounded.
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Extrusion
6063 billet run on one of two automated lines, cooled under control and aged to T5. Straightness is checked on the cut length, because a profile that measures well at the die can bow over a metre.
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CNC machining
End cuts to length, mounting holes, driver pocket and end-cap screw holes, all from the same datum as the board channel.
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Blast, anodize, inspect
180# bead blast without polishing, then anodizing in the approved colour, then dimensional and appearance check against the retained chip.
The numbers the part had to hold
These are the tolerances and process values that governed the job. They come from our capability, not from a customer specification we cannot publish.
| Parameter | Value | Why it mattered |
|---|---|---|
| Profile cross-section | ±0.05 mm | Keeps the board channel flat along the fixture |
| Wall thickness capability | ±0.02 mm | Controls how much heat reaches the fins |
| Fin pitch | 3–6 mm | Chosen for the fixture length and airflow |
| Board channel flatness | Agreed per part | Sets the thermal contact along the board |
| Alloy and temper | 6063-T5 | Extrudes thin fins well and anodizes evenly |
| Finish | 180# bead blast anodized | Uniform matte with no polishing marks on the visible face |
The part of this job that nearly went wrong
This is the section worth reading. Every program has one problem that decides whether the parts come out right, and it is usually not the one on the drawing.
High fin ratio would not fill
The first section put the fins close together relative to their height. In extrusion terms the metal has to flow into narrow slots and rejoin at the tip, and a die designed like a plain box section leaves the fin tips short and rounded.
The risk
Short fin tips mean less surface area than the thermal design assumes, and the loss is invisible on a dimensional drawing — the fins are there, just not full height.
What we changed
We redesigned the feeder and bearing length for the fin geometry, splitting the flow so each fin slot filled before the streams rejoined. The fin geometry the customer specified was kept; the die behind it changed.
Die lines landing on the visible face
A linear housing is mostly visible surface. In extrusion, the parting line and any die lines show up as faint longitudinal marks that anodizing makes more obvious, not less.
The risk
A part that passes dimensional inspection and gets rejected on appearance, after finishing, at the most expensive stage.
What we changed
The parting line was moved to a hidden edge of the section and the visible face was given a bead-blast texture that diffuses the surface. The texture is also the finish the customer wanted, so no extra process was added.
One part instead of two, with no thermal interface
The final part is a single 6063-T5 extrusion with the fins, the board channel and the end-cap interface formed together. Machining is limited to the ends, the mounting holes and the driver pocket.
Along the way the customer removed a separate heat sink, the thermal paste, a second supplier and a bolted joint that could loosen. The section holds ±0.05 mm and the finish is a bead-blast anodized matte with no polishing step.
The broader lesson is the one we repeat on every enclosure: if the shape can come out of a die, do not pay a machine to remove it.
Common questions about this program
The questions this case generates from engineers and sourcing teams.
Why not bolt a standard heat sink onto an extruded body?
Every bolted joint adds a thermal interface, a tolerance and a part to inventory. If the fin geometry can be extruded into the housing section, the interface disappears and so does the assembly step. The trade-off is that the section must be designed with the fins from the start.
What fin pitch can you run on a lighting housing?
Typically 3–6 mm, with finer arrays evaluated per section. The limit is not a number on a chart — it is whether the die can fill the fin slots at your wall thickness, which is why we check the section before quoting.
Does anodizing reduce the thermal performance of the housing?
The anodic layer is thin and is not the limiting factor in a natural-convection fixture; the fin area and the contact to the board matter far more. Where a masked, conductive surface is needed for grounding, we mask it at the machining stage.
Building a Fixture Where the Housing Is the Heat Sink?
Send the section and the board channel tolerance. We will tell you whether the fins will fill before a die is cut.
What to send
- 2D drawing or 3D model (STEP, IGES, DWG, DXF, PDF)
- Alloy and temper
- Surface finish and color
- Estimated annual quantity
Client names are withheld under confidentiality. Figures reflect our verified process capability.