Wexmar provides custom heat sink machining for electronics, electrical and instrumentation builders that need thermal parts made to their drawings. Our Canastota, New York shop produces CNC machined heat sinks, cold plate bodies, heat spreaders and thermal mounting blocks from aluminum and copper, and we finish machine extruded heat sink profiles.
What heat sinks do and who buys them
A heat sink draws heat out of a power device, processor, LED array or sensor and releases it into air or liquid. Extruded heat sinks cover many needs, but machining is used when the design needs pin fins or cross-cut fins, a very flat contact surface, bosses and pockets that match a board, mounting features on multiple faces, or copper where extrusion is not practical. Machined cold plates route coolant through drilled or milled passages. Buyers include power electronics and drive makers, electrical and connector companies, LED and laser system builders, test and instrumentation OEMs, medical device hardware suppliers and defense electronics programs.
How we machine CNC heat sinks
Heat sinks are machined on our six Mazak horizontal machining centers: two FH4800s, a PFH4800, a Nexus 4000-II and two Nexus 5000-II machines with pallet changers and 4th-axis rotaries. The horizontal spindle clears chips out of deep fin slots, which reduces recutting and helps fin surfaces stay clean. Several parts can be fixtured on a tombstone and machined on multiple faces in one setup, so mounting holes on the base and side faces stay in position. We finish the device contact surface in a dedicated final pass for flatness and finish. See horizontal CNC milling.
Round heat sinks for LEDs and cylindrical components are turned on our Mazak and Doosan lathes, with radial fins and mounting holes cut using live tooling. When an extruded profile is supplied, we cut to length on our KASTO saws and machine pockets, holes and flats to your drawing. See CNC turning.
Heat sink materials
- Aluminum: 6061-T6 for general use, 6063 extrusions, and 1100 or 6101 where higher conductivity is wanted.
- Copper: C10100 and C11000 for high heat flux spreaders and cold plates.
- Others: brass, and aluminum or copper plate from customer-specified sources.
Critical heat sink features and how we hold them
- Contact surface flatness: finished in a final light pass after the fins are cut and clamping stress is released, so the device seats with thin, even thermal interface material.
- Surface finish: held to the specified Ra for thermal contact.
- Fin thickness and pitch: cut with controlled tool deflection to keep fins straight and evenly spaced.
- Mounting hole position: located to the device footprint and verified on CMM.
- Coolant passages: for cold plates, drilled or milled channels with plugs or covers per the drawing.
Typical tolerances and finishes
| Feature | Typical tolerance | Tighter on request |
|---|---|---|
| Contact surface flatness | 0.002 in | 0.0005 in |
| Contact surface finish | 63 Ra | 32 Ra or finer |
| Fin thickness | ±0.005 in | ±0.002 in |
| Mounting hole position | 0.005 in | 0.002 in |
| Overall dimensions | ±0.005 in | ±0.002 in |
| Threads | UN 2B / metric 6H | Helical inserts |
These are typical values. Very thin, tall fins and large thin bases move during machining, and we will review aspect ratios with you before quoting.
Secondary operations
Black and clear anodizing, chem film, nickel plating for copper, thermal interface pad application, brazing or bonding of cold plate covers, and friction stir welding are performed through qualified outside processors. We specify masking of the contact surface so anodize or plating does not add thickness where it would affect thermal contact. Helical insert and PEM-style press insert installation is done in-house.
Quantity patterns
Heat sink programs usually begin with 2 to 10 prototypes for thermal testing, then move into production lots of 50 to 1,000. Pallet changers and a second shift keep production heat sinks moving.
Inspection
Contact surface flatness is measured on a surface plate and on our Brown & Sharpe CMMs, which also verify hole positions. Fins are checked with calipers and gages. CMM reports, AS9102-format first articles and material certs are available. See inspection and quality.
Getting a quote
Send a drawing and STEP model with material, flatness, finish and quantity. You can upload a drawing for an instant estimate, and an estimator will confirm pricing. Or call (315) 400-2654. Related: machined enclosures.