Aluminium is about one-third the weight of brass (~2.70 vs ~8.4–8.5 g/cm³), which decides most parts that move, fly or are hand-held. It also anodises, conducts heat well and is cheaper per part in larger sizes. Brass wins on threads and sealing (denser, less prone to galling), on wear surfaces and bushings, on fine-feature small turned parts, and on compact electrical contacts where density and solderability matter. Both machine well but on different rulers — free-machining 2011 aluminium cuts beautifully, while 6061 and 6082 are more ductile.
Brass and aluminium rarely compete on strength — they compete on weight versus everything brass is good at: threads that hold pressure, sealing faces, wear resistance and dense, solderable contacts. Get the weight question answered first, because it usually settles the argument, then check the properties below.
Brassland machines both brass and aluminium (as well as copper), so we build parts either way. This is a straight comparison of how the two behave.
Why there is no single "brass vs aluminium" machinability number
Aluminium machinability is usually quoted on an aluminium-specific scale, or as letter grades A to D, not on the copper-alloy scale that puts brass at 100. So "free-machining 2011 cuts superbly" and "brass = 100" are both true but live on different rulers. We describe machining behaviour here rather than assert a single cross-family ratio, because that ratio would be meaningless.
Brass vs aluminium: the numbers side by side
The table compares free-cutting brass with the three aluminium alloys most often machined: 2011 (free-machining, leaded), 6061 (general purpose) and 6082 (the European structural equivalent of 6061).
| Property | Free-cutting brass (C36000 / CW614N) | Al 2011 | Al 6061-T6 | Al 6082-T6 |
|---|---|---|---|---|
| Density (g/cm³) | ~8.4–8.5 | ~2.83 | ~2.70 | ~2.70 |
| Weight for equal volume | baseline | ~⅓ of brass | ~⅓ of brass | ~⅓ of brass |
| Machinability | Top of copper scale (100); clean chips, high speed | Excellent — free-machining (Pb+Bi), grade "A", small chips | Moderate; good but more ductile / stringy than 2011 (grade ~"C") | Moderate; slightly harder / less free-cutting than 6061 |
| Elastic modulus (GPa) | ~100 | ~70 | ~69 | ~70 |
| Ultimate tensile strength (MPa) | ~330–530 | ~380 (T3) | ~310 | ~290–340 |
| Thermal conductivity (W/m·K) | ~120 | ~150 | ~170 | ~170 |
| Electrical conductivity (% IACS) | ~26–29 | ~39 | ~43 | ~40 |
| Corrosion / finish | Corrosion-resistant bare; plated (Ni) for cosmetics/contact | Poor corrosion resistance (needs coating) | Good; anodises well | Good; anodises well |
| Typical finishing | Electroplating (nickel, etc.) | Anodise (limited) or plate | Anodising (adds ~no weight) | Anodising |
| Lead / compliance | Leaded grade (choose CW724R / C69300 if lead-free needed) | Contains Pb + Bi → often not RoHS-clean | Lead-free | Lead-free |
On conductivity, note the direction carefully. Per equal volume, 6061 (~43 % IACS) actually beats brass (~26 % IACS). But the numbers can flip on an equal-weight basis because aluminium is so light: for weight-critical bus or conductor work aluminium is strong, whereas for compact, dense contacts and connectors brass is usually preferred for its combination of conductivity, machinability, solderability and wear at small sizes.
On "gummy" machining: it is the 6000-series and soft or annealed tempers that tear and build up on the edge. Free-machining 2011 avoids this with lead and bismuth — which is exactly why it exists, at the cost of RoHS compliance.
When each wins (honest)
Aluminium wins when…
Weight matters — at roughly one-third of brass it is decisive for anything that moves, flies or is hand-held; raw material cost per part is lower for larger parts; you need high thermal conductivity (heat sinks); or you want a light, non-magnetic, anodisable finish. Free-machining 2011 cuts beautifully; 6061 and 6082 give strength-to-weight and anodise well.
Brass wins when…
The part has threads and sealing faces (denser, less prone to galling and thread pickup, better for fittings made and broken repeatedly); it is a wear surface or bushing; it is a fine-feature small turned part where chip control at high speed matters; it is a compact electrical contact where density and solderability count; or a machined thread must hold pressure without an insert. Brass also plates readily for cosmetic or contact finishes.
How Brassland fits in
We machine both families. For brass, that means free-machining CW614N for high-speed turned parts, or lead-free grades where compliance demands it. For aluminium and copper custom work, see aluminium & copper parts. If weight is the deciding factor we will steer you to aluminium; if the part lives or dies by its threads, sealing or wear, brass is usually the right call.
Frequently asked questions
How much lighter is aluminium than brass?
Which machines better, brass or aluminium?
Do I anodise the aluminium or plate the brass?
For an electrical connector, brass or aluminium?
Is aluminium 2011 RoHS compliant?
Sources & references
Figures on this page are drawn from published alloy datasheets, standards bodies and engineering references. Key sources:
Last reviewed: July 2026. Material and process figures are checked against datasheet and standards references at each review. Cross-material machinability numbers are indicative (see note in the article), not two points on one physical scale.
Need this part in the right alloy?
Brassland machines precision brass, copper and aluminium components to your drawing — Swiss turning to ±0.005 mm, CNC machining in-house, and hot forging through qualified partners. Send a drawing and we will get back to you.
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