What is C360 Brass Used For

1. What is C360 Brass Used For?

C360 brass (officially designated as UNS C36000, often called "free-cutting brass" or "leaded brass") is a versatile alpha-beta brass alloy composed of ~61.5% copper, ~35.5% zinc, and ~3% lead. Its defining trait-excellent machinability (due to lead, which acts as a lubricant during cutting)-makes it ideal for high-volume production of precision parts that require complex machining.

Key applications include:

Fasteners: Screws, nuts, bolts, washers, and rivets-especially small, precision fasteners for electronics, appliances, and automotive components, where tight tolerances and easy machining are critical.

Mechanical components: Gear teeth, valve stems, pump parts, and fitting bodies (e.g., for plumbing or pneumatic systems). Its balance of strength and machinability allows for intricate shapes (e.g., threaded holes, grooves) without excessive tool wear.

Electrical parts: Terminal blocks, connectors, and switch components. While not as conductive as pure copper, its machinability and moderate corrosion resistance suit non-critical electrical applications.

Hardware and consumer goods: Cabinet knobs, drawer pulls, clock parts, and toy components. It can be polished to a bright finish for decorative appeal, combining functionality with aesthetics.

Aerospace and automotive: Small precision parts like sensor housings, fuel system fittings, and instrument components-where reliability and consistent machining performance are essential.

2. What are the Advantages of C360 Brass?

C360 brass's popularity stems from a unique combination of properties that address the needs of high-volume manufacturing and precision engineering. Its key advantages include:

(1) Exceptional Machinability

The 3% lead content is the primary driver of its standout machinability. Lead particles act as internal lubricants, reducing friction between the cutting tool and the alloy during machining (e.g., turning, drilling, milling). This results in:

Faster production speeds (higher feed rates and cutting speeds).

Minimal tool wear (extending tool life and lowering tool replacement costs).

Clean, smooth cuts with tight tolerances (critical for precision parts like threaded fasteners).

It is often rated as having "excellent" or "superior" machinability compared to other brass grades (e.g., C260 cartridge brass) and even many non-ferrous metals.

(2) Good Strength and Hardness

As an alpha-beta brass, C360 balances machinability with sufficient mechanical performance. Its typical mechanical properties (annealed temper) include:

Tensile strength: ~485–550 MPa (70,000–80,000 psi).

Yield strength: ~240–275 MPa (35,000–40,000 psi).

Hardness: ~80–90 HRB (Rockwell B scale).

This strength is adequate for most fasteners, fittings, and small mechanical parts, where it resists deformation under typical operating loads.

(3) Moderate Corrosion Resistance

C360 brass offers decent corrosion resistance in mild environments, such as air, freshwater, and non-aggressive industrial fluids. It forms a thin, protective oxide layer that slows tarnishing and prevents significant degradation. While not as corrosion-resistant as high-copper brasses (e.g., C230 red brass) or stainless steel, it performs well in indoor, dry, or low-moisture applications (e.g., electronics, cabinet hardware).

(4) Easy Finishing

C360 brass accepts a wide range of surface finishes to enhance aesthetics or functionality:

Polishing: It can be buffed to a bright, reflective metallic finish for decorative use (e.g., hardware, consumer goods).

Plating: It readily takes electroplating with nickel, chrome, or gold to improve corrosion resistance or create a premium look.

Painting/coating: It adheres well to paints and clear coats, further protecting against tarnish.

(5) Cost-Effectiveness for High-Volume Production

Its fast machinability reduces labor and production time, while its relatively low raw material cost (compared to copper or high-nickel alloys) makes it economical for mass-produced parts. Tooling savings (due to minimal wear) further lower overall manufacturing costs.

3. What are the Drawbacks of C360 Brass?

Despite its strengths, C360 brass has notable limitations that restrict its use in certain applications:

(1) Lead Content: Health and Environmental Risks

The 3% lead content-while critical for machinability-is its most significant drawback. Lead is a toxic heavy metal that poses risks:

Health hazards: Inhalation of lead dust (from machining) or ingestion (e.g., via contaminated water in plumbing parts) can cause neurological damage, kidney issues, and developmental problems (especially in children). This prohibits C360 from use in applications involving potable water (e.g., drinking water pipes, faucets) or food contact (e.g., kitchen utensils), as regulated by standards like the U.S. Safe Drinking Water Act (SDWA) or EU REACH.

Environmental concerns: Lead leaching from discarded C360 parts can contaminate soil and water. Many regions have strict regulations on lead-containing materials, requiring special handling during manufacturing, use, and disposal.

(2) Poor High-Temperature Performance

Lead in C360 brass has a low melting point (~327°C/621°F). At temperatures above ~200°C (392°F), lead begins to soften and migrate, causing:

Reduced strength and hardness (the alloy may deform under load).

Increased brittleness (risk of cracking in high-temperature applications).

This makes C360 unsuitable for use in high-heat environments, such as engine components, industrial ovens, or exhaust systems.

(3) Limited Corrosion Resistance in Aggressive Environments

While it resists mild corrosion, C360 brass performs poorly in harsh conditions:

Saltwater/brackish water: It is prone to dezincification (a type of corrosion where zinc is leached from the alloy, leaving a porous, brittle copper structure) in marine or coastal environments. This rules out use in boat hardware, seawater pipes, or offshore components.

Acids/alkalis: It reacts with strong acids (e.g., sulfuric acid) and alkalis, leading to rapid degradation. It cannot be used in chemical processing equipment or applications involving corrosive fluids.

(4) Reduced Ductility and Weldability

Lead particles disrupt the brass's microstructure, making C360 less ductile than lead-free brass grades (e.g., C37700). It is difficult to cold-work (e.g., bending, drawing) without cracking, limiting its use in parts requiring significant forming.

Additionally, lead vaporizes during welding or brazing, creating toxic fumes and weakening the weld joint. Welding C360 brass is not recommended, and brazing requires specialized techniques (e.g., low-temperature fillers) to minimize lead release.

(5) Lower Electrical and Thermal Conductivity

Compared to pure copper or low-zinc brasses, C360 has lower electrical conductivity (~25–30% of pure copper) and thermal conductivity. This makes it unsuitable for high-performance electrical applications (e.g., power cables, bus bars) or heat exchangers, where efficient energy transfer is critical.