C260 Brass for Connector Parts: What You Can Specify, and What the Machine Shop Must Supply

Rule out C260 as a drop-in for leaded brass before you write any parameter

The first decision is not a speed or a coating — it is whether C260 belongs on the drawing at all. C26000 is 70% copper and 30% zinc with no lead, and it carries a machinability rating of 30% against 100% for leaded C36000, which is the reference standard for that rating¹⁵.

That gap is the mechanism you are buying into: the same source ties C360's higher rating to faster cycle times, lower tool wear, shorter discontinuous chips and better surface finish at higher cutting speeds. And describes C260 as producing longer chips and higher tool wear and needing lower cutting speeds¹⁵.

Treat the rating as a direction of travel, not a multiplier — nothing in this evidence lets you convert 30% into a surface speed. One supplier's position is that C360 is better for CNC machining in almost every case.

And that the only reasons to choose C260 for a machined part are that RoHS compliance prohibits lead or that the part also needs cold forming such as drawing, bending or spinning¹⁵. If your connector is a high-volume turned part and lead is permitted, that position points away from C260.

If lead must be avoided, or the part is formed as well as machined, C260 becomes the material choice despite its rating¹⁵.

Call out a temper, and know what the callout does and does not control

Temper is a real specification variable for C260, because the mechanical properties move a long way across the temper range.

Copper.org lists C26000 flat products from H01 through H10, with typical tensile strength climbing from 54 ksi at H01 to 99 ksi at H10 and typical elongation falling from 43% to 3% over the same span²⁶.

AZoM gives the same picture as a range: roughly 303–896 MPa tensile and 76–448 MPa yield depending on temper¹³. A connector contact that must bend without cracking and a connector body that must hold its shape are therefore asking for different tempers from the same alloy.

What the sources do not give you is the machining consequence. Neither datasheet links temper or grain size to machinability, cutting behaviour or distortion during machining^13,26, so you cannot pick a temper on the grounds that it machines better.

Specify the temper the part's function needs, and put the machining question to the shop as a separate item.

Choose a coolant delivery method, and keep amines away from the fluid

Coolant selection for C260 splits into two separate questions: how the fluid is delivered, and what chemistry the fluid must not contain. On delivery, the general principle is to match the method to the dominant failure mode.

Flood coolant is the strongest option for cooling and chip evacuation, MQL gives the most lubrication per unit of fluid volume. And dry machining leans entirely on the tool material's heat resistance and chip-breaker geometry for chip control²¹.

Lubrication matters more than cooling at low cutting speeds, which is where MQL can be favoured²¹. C260's long-chip tendency¹⁵ makes chip evacuation a live concern, which is the argument for flood.

But the sources give no brass-specific coolant guidance, so confirm the choice with the shop against your actual operation. On chemistry, the constraint is harder.

Brasses with more than about 15% zinc may suffer dezincification, and alloys above that threshold are the most susceptible to stress-corrosion cracking, particularly from ammonia and amines²². C260 sits at 30% zinc, well past that line^15,22.

Write a fluid specification that excludes ammonia- and amine-bearing coolants unless the shop can show you why not, and note that annealed temper and stress relief after forming reduce SCC susceptibility²².

Parameters to request from the shop rather than assume

The sources in this set do not carry the process data a C260 connector spec needs, so each of these belongs in the RFQ as a question to the machine shop or the material supplier. Asking for them explicitly is how you avoid a quote built on leaded-brass assumptions.

• ✓Surface speed and feed for C260 in the actual operation (turning, milling), with the tool substrate and grade named — no source here gives a numeric value
• ✓Tool coating or substrate recommendation, and the shop's view on built-up-edge or adhesion risk with copper-zinc alloys — not addressed in this evidence
• ✓Achievable tolerance and surface roughness (Ra) for the specific features, quoted against your drawing rather than assumed from another alloy
• ✓Tool-life expectation and change interval, so the quote's cycle time reflects realistic tool consumption
• ✓Deburring method and edge condition for connector contacts and mating faces, including whether plating follows deburring
• ✓How the shop will control distortion from residual stress in the stock and dimensional drift from tool wear, since both bear directly on holding connector tolerances

Volume and lead time: ask, because the sources set no thresholds

The machinability gap changes the economics of volume, but the sources give you no lot-size threshold at which C260 stops making sense. What you can do is make the shop price the difference explicitly: ask for cycle time and tool consumption per part in C260.

And — if lead is permitted — the same part in C360 for comparison¹⁵. That comparison is the number that decides whether the lead-free requirement is worth its cost, and it comes from your shop, not from this evidence.

Lead time is the same story. No source here gives tooling lead times, finishing lead times or volume breakpoints for brass connectors.

So put the question to the shop as part of the RFQ and treat any figure you receive as that shop's estimate for 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.
• Ask the supplier for model-specific evidence and record the condition that would change your buying decision.
• Request the complete specification sheet with units, test conditions and configuration assumptions.
• 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.