Types of Heat Sinks and how to choose between them
Heat Sinks is a machined or extruded finned body that carries heat away from a component. It is used for power electronics, LED assemblies and any enclosure that generates heat. This entry explains what it is, what the numbers on a data sheet mean, and what to put on a drawing.
It is written from the point of view of the buyer and the drawing office: the values that are realistic in production, the ones that cost money, and the way the result is verified. Where an industry sets the requirement, rail is used as the example: documented welds, coatings and fire smoke toxicity compliance.
The main types
Heat Sinks is not one thing. The variants below differ in what they suit, and the choice is usually made on the part rather than on preference.
- Extruded fin with a machined base – suited to power supplies.
- Machined pin fin – suited to motor drives.
- Skived fin – suited to LED luminaires.
- A milled pocket in the enclosure itself – suited to telecom enclosures.
How to choose
Start from the feature that has to work, then from the quantity. A rail run suits one arrangement, a repeat run suits another, and the wrong choice shows up as cost rather than as failure.
The second question is what has to be measured. Where in-house approval with dimensional reports applies, the inspection requirement usually decides the route before the machine does.
Comparison at a glance
| Parameter | Value |
|---|---|
| Material | aluminium, or copper for a spreader |
| Fin thickness | 1 to 3 mm typical |
| Fin pitch | 3 to 10 mm |
| Flatness of the base | 0.05 mm over 100 mm |
| Surface finish | Ra 1.6 µm on the mounting face |
| Options | anodised black, or nickel plated |
Applications
Heat Sinks is used for power electronics, LED assemblies and any enclosure that generates heat, and in practice it appears most often in power supplies, motor drives, LED luminaires, telecom enclosures.
How it fits into a machining route
Heat Sinks is produced by whichever route reaches it most reliably, and it is usually the reason the rest of the part is dimensioned the way it is. Datums are chosen so that this feature is measured from what it actually has to be square or concentric with.The route is fixed before the first part is cut, and it is the route rather than the individual setting that holds the result: fin count and the machining time on the base. Where a drawing calls for something the route cannot hold economically, that is raised at quotation rather than after the parts are made.
Standards, documentation and what is issued
The documentation requirement is in-house approval with dimensional reports. Material is supplied against a certificate where the application calls for it, inspection results are recorded with the job, and the records are kept so that a repeat order can be compared with the first instead of being measured from scratch.
Flatness check on a plate, plus a visual check of the fins is the verification step. Where a customer format or a standard report is required, it is agreed before the batch starts, because a report written after the event is a report nobody can use.
Frequently asked questions
What tolerance should be specified for Heat Sinks?
±0.05 mm on the mounting face is realistic in production. Tightening it beyond the functional requirement increases cost without improving the part.
Which material is usually used?
6063-T5 aluminium is the usual choice, supplied against in-house approval with dimensional reports.
How is the result verified?
Flatness check on a plate, plus a visual check of the fins, with the results recorded so a repeat order can be compared with the first.
What is the most common mistake?
Fins so thin that the tool deflects and they vary in height.
How long does it take and what does it cost?
A realistic cycle is 20 to 90 minutes depending on the fin count, and the cost driver is fin count and the machining time on the base.
Related capability
If you are specifying Heat Sinks on a drawing and want a second opinion on the route, send the model and the quantity. The first response is a manufacturability review with the likely risk points and a quotation, so the decision can be made on facts rather than on a price alone.
Machining, inspection and documentation are handled in one place, which is why the dimensional report and the material certificate arrive with the parts rather than after them.
Related entries
These entries sit next to Heat Sinks in the encyclopedia: Bearing Housings, Hydraulic Manifolds, First Article Inspection. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.
