Brass 260 Sheet Fabrication

The deep-drawing reference

Brass 260 is a single-phase alpha brass — all of the zinc is held in solid solution, so there are no second-phase particles to start a crack as the material is stretched. That is what makes it the most formable brass there is, and it is formable enough that whole industries are built on it.

Property	Brass 260	What it means
Formability	Excellent — the reference grade	Severe cold reduction between anneals
Bend radius, annealed	~0.5–1× thickness	Comparable to mild steel, tighter than most non-ferrous sheet
Work hardening	Significant	Multi-operation forming may need an inter-anneal
Copper content	~69%	Better corrosion resistance and deeper colour than free-cutting brass
Lead	None	The lead-free brass
Conductivity	~28% IACS	Adequate for general electrical hardware
Weldability	None	Braze or solder instead

Cartridge cases, radiator cores, eyelets, lamp fittings, snap fasteners and instrument housings are all deep drawn from it. The grade takes very severe cold reduction between anneals without cracking, which is exactly what drawing a case from a flat disc requires.

Work hardening and the inter-anneal

Forming brass work-hardens it, and the effect is large.

On a part with one or two forming operations, that is an advantage — the finished part is stronger than the sheet it came from, and the temper you specify and the forming you do combine to set the final strength.

On a part with several forming operations, or one with a severe draw, the material may need an inter-anneal partway through the route to restore enough ductility to continue without cracking. That adds a process step and it also means the part is being formed in more than one condition.

So on a complex formed brass part, the sequence is a design decision:

1. Blank and form in the annealed or a light temper
2. Inter-anneal if the forming is severe enough to exhaust the ductility
3. Continue forming to the finished geometry
4. Stress relieve if the part will see ammonia or amines
5. Finish by polishing, brushing or plating

Raising a multi-operation draw at the enquiry is what allows that sequence to be planned rather than discovered when the first blanks crack.

Stress relief, and the ammonia question

Brasses are susceptible to stress-corrosion cracking in ammonia and amine environments. Cold forming leaves residual stress in a part, and where that part also meets ammonia, cracks can open and spread under what would otherwise be an unremarkable load.

The sources of ammonia are not only industrial:

• Ammonia-based cleaning agents, which are common in kitchens, laboratories and washrooms
• Refrigeration systems, where ammonia is a common refrigerant
• Certain process fluids and some agricultural chemicals
• Amine-containing products, including some epoxy hardeners and corrosion inhibitors

The standard prevention is to stress relieve cold-formed parts destined for that kind of service. The standard first step is simpler: say at the enquiry what the part will touch. A brass part in a benign indoor environment needs nothing; the same part in an ammonia environment needs a stress-relief step in the route.

Joining

Brass 260 is not a welding grade. Brasses are difficult to fusion weld because the zinc volatilises and the joint comes out porous — and cartridge brass is no exception.

The joining routes are brazing and soldering, and the grade takes both very well. Both are low-temperature processes that do not disturb the material’s condition, and both are well understood in brass work. Where an assembly has to be joined, designing for a braze or a solder joint rather than a weld is what makes the part straightforward — and a mechanical joint is often simpler still.

Formed-feature rules

The geometric rules around a bend are moderate on brass 260.

Holes and slots must clear the bend. A hole inside the bend zone distorts as the material stretches around the radius. The working rule is to keep a hole at least a distance of roughly two-and-a-half times the material thickness plus the bend radius away from the bend line — measured from the edge of the hole, not its centre.

Flanges have a minimum length. A flange shorter than roughly four times the material thickness cannot be formed reliably, because the tooling has nothing to grip and the bend does not develop properly.

Bend relief prevents tearing, and on a multi-operation part it is worth including rather than relying on the material’s ductility.

Springback is modest but present. Brass springs back less than stainless or aluminium, so it forms predictably — but the bend allowance in the flat pattern should still account for it.

Annealing softens; forming hardens. Where a part needs to be both heavily formed and strong, the answer is usually to form it in a soft temper and accept the work-hardened strength that results, rather than to specify a hard temper and then try to form it.

Where brass 260 sheet is the right choice

• Deep drawn parts — cartridge cases, eyelets, housings, shells
• Radiator cores and heat-transfer fins
• Snap fasteners, contacts and small formed electrical hardware
• Formed instrument trim and bezels
• Architectural and decorative formed brass work
• Any brass part that must be lead-free — the primary reason the grade appears on a modern drawing
• Potable-water fittings and components, where leaded brass is generally not acceptable

Where brass 260 sheet is the wrong choice

The part is turned or milled rather than formed. Brass 260 machines poorly because it has no lead. Where the part is cut and the free-cutting brass’s lead content is acceptable, brass 360 cuts several times faster.

The part meets ammonia or amines and cannot be stress relieved. Stress-corrosion cracking is a real risk in that environment. Name the chemical so it can be reviewed.

The assembly has to be welded. Brasses are not fusion-weldable in practice. Design for a braze or a solder joint, or reconsider the material.

High-conductivity electrical duty is required. At around 28% IACS, brass is about a quarter as conductive as pure copper. Copper 110 is the conductor sheet.

The part must stay bright without a coating. Bare brass tarnishes. A lacquer or a plating is needed, and it should be specified rather than expected.

The part sits in prolonged contact with aggressive water. Dezincification and stress cracking are both environment-driven risks worth reviewing before the grade is fixed.

What to put on the drawing

Instead of	Write
Brass sheet	Brass 260, and specify the temper — annealed through spring
Brass 260, multi-operation draw	Say so — an inter-anneal step may be needed in the route
Brass 260, ammonia or amine contact	Flag it — stress relief is required to prevent cracking
Brass 260, will be welded	Not a welding grade — braze or solder instead
Brass 260, must stay bright	State the finish — bare brass tarnishes
Brass 260, high-current conductor	Wrong material at ~28% IACS — copper 110 is the conductor sheet
Brass 260, turned part in volume	Brass 360 machines far faster if lead is acceptable
Brass 260, potable water	Correct — it is the lead-free brass

The three lines that decide most brass 260 sheet parts are how many forming operations are involved, whether the part meets ammonia, and how it is joined. The first decides whether an inter-anneal belongs in the route. The second decides whether a stress relief does. The third rules welding out and points at brazing or soldering.

Send the drawing through the request a quote form and the reply comes back within 24 hours with DFM feedback — including a note on the temper, the forming sequence, any inter-anneal or stress relief and the finishing where any of them need settling.