Cast Aluminum Heat Sink RFQ Checklist: Thermal Target, Fin Fill, Flatness, and Surface Finish

# Cast Aluminum Heat Sink RFQ Checklist: Thermal Target, Fin Fill, Flatness, and Surface Finish

Cast aluminum heat sinks look simple until a buyer tries to compare quotes. One supplier may quote a raw casting. Another includes CNC base machining, flatness records, surface finish, and inspection. A third assumes the buyer owns thermal validation. Those quotes are not comparable.

This checklist helps sourcing, thermal, and quality teams prepare a quote-ready RFQ for cast aluminum heat sinks used in LED fixtures, power electronics, telecom modules, inverter covers, controller housings, and thermal-management assemblies.

Helpful Bohua routes:

• •Cast aluminum heat sink RFQ path
• •Heat sink application guide
• •Gravity casting process
• •A356 material guide
• •Casting process selection guide

1) Start with the thermal target, not only the drawing

The supplier needs more than shape and weight. Include:

• •heat source and estimated wattage
• •maximum allowed surface or junction temperature if known
• •cooling condition: natural convection, forced air, liquid-adjacent, or assembly-specific
• •orientation and airflow notes if they affect fin layout
• •whether the buyer owns thermal simulation or expects supplier DFM feedback only

If the final thermal model is confidential, share an anonymous target range and the part function. The quote can still separate casting, machining, and inspection assumptions.

2) Define fin geometry and fill-risk zones

Thin fins, tall fins, deep gaps, and abrupt wall changes can drive mold design and process choice. Mark:

• •minimum fin thickness
• •fin height and gap
• •root radius or transition areas
• •areas where incomplete fill is unacceptable
• •cosmetic vs functional surfaces

If the design is still flexible, ask the supplier to flag fin geometry that may need draft, radius, wall-thickness change, or a different process route.

3) Base flatness and contact surface requirements change the quote

For many heat sinks, the most important feature is the contact surface, not the largest visible fin field.

State:

• •flatness target for the base or mounting pad
• •whether the base is machined
• •required surface roughness if thermal interface material depends on it
• •datum scheme for inspection
• •whether flatness is checked before or after coating

If you only write "flat surface required," suppliers will assume different machining and inspection levels.

4) Material and process route: A356, ZL114, ADC12, or supplier recommendation

For gravity-cast or low-pressure-style heat sinks, A356 or ZL114 may be discussed when strength, thermal path, and post-cast machining matter. ADC12 or similar die-casting alloys may fit higher-volume thin-wall covers or housings, depending on the geometry and validation plan.

Use the RFQ to say one of:

• •required alloy from the drawing
• •approved alloy family with equivalents allowed
• •supplier recommendation requested with reason

Do not force an alloy only because it appears in another product unless engineering has approved it.

5) CNC, coating, and finish scope must be separated

Ask suppliers to separate:

• •raw casting
• •CNC base or mounting pad machining
• •tapped holes or inserts
• •deburring and cleaning
• •coating, anodizing, powder coating, or conversion coating
• •packaging protection for fins and machined faces

Surface finish choices can affect flatness, masking, thermal contact, and cost. The RFQ should state whether coating is cosmetic, corrosion-related, insulation-related, or only a buyer-side downstream step.

6) Inspection records for heat sink RFQs

Useful evidence may include:

• •base flatness report
• •CMM or fixture report for mounting holes and datums
• •fin-fill visual criteria or photo record
• •material certificate
• •surface finish or coating record if required
• •first article report when the part is new tooling

If the buyer will perform thermal validation, say whether supplier-side records only need to support dimensional release.

Copy-paste RFQ starter

> Cast aluminum heat sink RFQ

> Files: 2D PDF rev __, STEP __, NDA-first review yes/no __

> Application: LED / telecom / inverter / controller / power electronics / other __

> Heat source or wattage: __

> Cooling condition: natural / forced air / assembly-specific __

> Alloy target: A356 / ZL114 / ADC12 / supplier recommendation __

> Process target: gravity casting / low-pressure / die casting / supplier recommendation __

> Fin geometry: minimum fin thickness __, height __, gap __

> Base requirements: flatness __, roughness __, machined yes/no __

> Machining scope: base __, holes __, threads/inserts __

> Finish: bare / coating / anodize / powder coat / buyer-side __

> Inspection records: flatness __, CMM __, material certificate __, first article __

> Quantity: prototype __, annual volume __

> Destination and Incoterm: __

Start a structured heat sink RFQ

When drawings are ready, use the heat sink RFQ upload path so thermal, machining, and inspection context stays attached to the inquiry.

FAQ

Does every cast heat sink need CNC machining?

No. Many heat sinks only need selected contact faces or mounting features machined. The buyer should define which surfaces are functional and which are cosmetic or as-cast.

Should the buyer send thermal simulation files?

Only when company policy allows it. A buyer can start with anonymous thermal targets, wattage range, airflow context, and the drawing package.

Which quote page should this article route to?

Use the Cast aluminum heat sink RFQ path for drawing-ready heat sink projects, then attach the RFQ package through the structured upload path above.