C260 Cartridge Brass vs C220 Commercial Bronze for Stamped Sheet: What the Evidence Settles and What the RFQ Must Ask

Why C220 cannot be selected on a like-for-like formability basis

The two alloys are not evidenced on the same axis. C260 is an alpha brass with a single-phase structure at room temperature, and the sources link that structure to its ductility and cold-working capability, which is why it appears in deep-drawing and bending work²⁶¹¹.

C220 is described only by its copper content and its corrosion resistance, with electrical and decorative components as typical uses³. Availability is not the gap.

A distributor stocks C220 commercial bronze sheet and plate alongside C260 cartridge brass, in soft and half-hard tempers, and lists stamping, drawing and spinning among the intended processes²⁷.

What is missing is the number that would let you compare: no elongation, no bend radius and no temper-specific property data for C220 appears in these sources³²⁷. That leaves you with a qualification problem rather than a datasheet comparison.

If C220 is attractive for another reason — corrosion service, for instance — the formability case has to be built from trial parts and the mill's own property sheet, not from published figures.

Fix the C260 temper first: it decides whether the part forms at all

Temper is the single largest lever on C260 formability, and it is set on the drawing before any tooling is cut. Elongation falls from 43% at H01 to 25% at H02, then to 8% at H04 and 5% at H06, while tensile strength climbs in the opposite direction¹⁸.

A part that draws cleanly in H01 may crack in H04 at the same bend radius. Harder tempers also need larger bend radii to avoid cracking, and bend orientation relative to the rolling direction further reduces formability⁹.

So the temper choice and the bend radius are one decision, not two: pick the softest temper the part's strength requirement allows, then set the radius from that temper. The values above are typical flat-product properties measured at a 0.04 in section, so confirm them for your actual gauge¹⁸.

Set the bend radius knowing the sources disagree

Two guidelines in this set point in different directions. A general stamping reference puts the internal bend radius for ductile sheet metals at about 1.0–1.5x material thickness as a practical starting point, with harder alloys and tempers needing larger radii⁹.

A separate fabrication table lists C260 cartridge brass at 0.5x thickness minimum³⁶. Both are vendor-tier guidelines rather than alloy-specific test data, and neither states the temper or thickness it applies to.

The disagreement matters because the die is cut once. A radius set at 0.5x on the strength of the C260-specific figure may be too tight for a harder temper.

And the general 1.0–1.5x figure may cost you forming severity you did not need in soft temper⁹ (supplier-reported figure). Treat the tighter figure as a target to verify, not a default to build to.

What settles it is your supplier's own bend data for the temper and gauge you are buying. Ask for their minimum inside bend radius by temper and thickness before releasing the die drawing, and treat any published figure — including the two above — as a starting point for that conversation.

Weigh C220's higher copper content against a price no source gives you

C220 runs at roughly 90% copper³ (supplier-reported figure); C260 is specified at 68.5–71.5% copper with zinc as the balance³¹⁸. Zinc is described as improving strength, hardness and cost efficiency compared with pure copper¹¹.

On composition alone, that points to C220 carrying the higher raw-material cost, because more of its mass is the more expensive element. Direction is all you get.

No source in this set publishes a price, a mill surcharge or a quantity break for either alloy at any gauge or temper, so the size of the gap is unknown³¹¹. Do not let a composition-based expectation stand in for a quote.

The corrosion side is similarly directional. C220 is characterised by high corrosion resistance and C260 by excellent ductility and formability, but no source quantifies either against a defined service environment³.

If corrosion resistance is what draws you to C220, that requirement needs its own test or specification — the formability trade is a separate question.

Compare finished-part cost, not metal price

For copper-alloy stamping, finished-part cost is described as material price plus strip utilization, scrap, tooling life, cycle rate and secondary operations³⁴. That structure means the cheaper alloy per pound is not automatically the cheaper part.

A material that forms without failures can reduce scrap and secondary processing enough to offset a higher metal price³⁴. Strip layout and material utilization carry real weight for relatively valuable copper alloys, so the nesting of your part in the coil affects unit cost as much as the alloy choice does³⁴.

When you compare C260 and C220 quotes, compare them on the same strip layout and the same assumed scrap rate, or the comparison measures the quotation rather than the material. This is also where an unproven alloy gets expensive.

If C220's forming behaviour is unknown, the trial runs, potential die adjustments and scrap from the learning curve belong in its cost case — not in a footnote.

Confirm both alloys are stocked in the form and temper you need

Supply is not the constraint on this decision. One distributor lists C220 commercial bronze, C260 cartridge brass and C280 Muntz metal sheet and plate as in stock for immediate shipment, in thicknesses from 0.20 in to 1 in, widths 36–48 in, tempers soft and half hard, with stamping among the listed processes²⁷.

C260 is also commonly supplied as sheet, strip, coil and plate, and is frequently specified under ASTM and SAE standards for flat products²⁶. Two caveats follow from that.

The distributor's stock tempers are soft and half hard, which map to the ductile end of the C260 temper range rather than the H04 and H06 grades²⁷¹⁸.

And the listed thickness range starts at 0.20 in, so if your part runs in thin strip, availability has to be confirmed for your gauge rather than assumed from the stock list²⁷.

What to put in the RFQ so the missing figures come back

The sources leave C220's properties, both alloys' prices and the process data unstated, so the RFQ is where those gaps get closed. Ask for each item in writing and require it per alloy, per temper and per gauge.

• ✓Ask the mill or distributor for C220 elongation, tensile and yield by temper at your gauge — no source in this set publishes them.
• ✓Ask for C260 and C220 price per pound or per square foot at your gauge, temper and quantity, including mill surcharge and quantity breaks.
• ✓Ask your stamper for minimum inside bend radius by alloy, temper and thickness, and for their K-factor table.
• ✓Ask whether the quoted temper is soft, half hard or harder, and confirm the elongation that temper delivers.
• ✓Ask for a trial run on C220 before committing tooling, and price the trial separately from production.
• ✓Ask for the mill test certificate or material certification for the specific heat and standard supplied.
• ✓Ask for strip utilization and expected scrap rate on the same layout for both alloys, so the cost comparison is like for like.

Where the sources disagree on C260's minimum bend radius

The two figures are not measuring the same thing: one is a C260-specific fabrication guideline, the other a general starting point for ductile sheet metals that explicitly widens for harder tempers³⁶⁹. Neither states the temper or thickness it applies to, so neither can be adopted as your drawing value without confirmation.

If your part runs in H01 or H02, the tighter figure is the one worth testing first; if it runs in H04 or H06, the general guideline's warning about harder tempers applies directly¹⁸⁹. Either way, the number that goes on the die drawing should come from the shop forming your part.

Before you request a quote

• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Request a written quote with price basis, MOQ, tooling, payment terms and production lead time.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.