Technical Guide
8 min read
Types of Brass Used in Manufacturing: A Practical Guide
A technical guide to brass alloy grades used in precision component manufacturing. Covers CW614N free-cutting brass, lead-free brass, naval brass, DZR brass, and Indian and international standard references.
What Is Brass?
Brass is a copper-zinc alloy. The proportion of zinc — typically between 5% and 45% — and the addition of small amounts of other elements (lead, tin, aluminium, arsenic, silicon) determine the alloy's mechanical properties, machinability, corrosion resistance, and appropriate applications.
In precision component manufacturing, the choice of brass grade directly affects machining speed, surface finish quality, tool life, thread accuracy, and the component's suitability for its service environment. Not all brass is the same, and specifying the correct grade at the drawing stage avoids costly substitutions or performance failures.
The Most Common Brass Grades in Precision Manufacturing
| Common Name | Designation | Composition (approx.) | Key Characteristic |
|---|---|---|---|
| Free Cutting Brass | CZ121 / CW614N / IS 319 | 58% Cu, 39% Zn, 3% Pb | Best machinability — default for CNC turning |
| Corrosion-Resistant Brass | CZ131 / CW606N | 63% Cu, 36% Zn, 1% Pb | Better corrosion resistance; moderate machinability |
| DZR Brass | CZ132 / CW602N | 61% Cu, 37% Zn, 2% Pb, As-treated | Resists dezincification in hot water systems |
| Free Machining Brass (USA) | C36000 / ASTM B16 | 61.5% Cu, 35.5% Zn, 3% Pb | US-market equivalent of CW614N for screw machine parts |
| Forging Brass | C37700 / ASTM B124 | 60% Cu, 38% Zn, 2% Pb | Excellent hot forgeability; valve bodies, hydraulic fittings |
| Cartridge Brass | C28000 / CW508L | 70% Cu, 30% Zn | Excellent cold forming and deep drawing |
| Naval Brass | CW712R / IS 4170 | 59% Cu, 40% Zn, 0.75% Sn | Improved corrosion resistance in seawater |
| Lead-Free Brass | CW510L / IS 319 Pb-free | 63% Cu, 37% Zn, <0.1% Pb | RoHS compliant; for drinking water contact |
| High Tensile Brass | CW721R | 58% Cu, 39% Zn, 1% Mn, 1% Fe, 1% Al | Higher tensile strength for structural parts |
Free Cutting Brass (IS 319 / CW614N): The Machining Standard
Free cutting brass is the material of choice for over 90% of CNC-turned brass components globally. Its high lead content (approximately 3%) acts as an internal lubricant and chip-breaker during machining: it allows the metal to break into short, discrete chips rather than long stringy swarf, resulting in higher cutting speeds, better surface finish, longer tool life, and reduced risk of tool breakage.
In India, this alloy is standardised as IS 319 by the Bureau of Indian Standards (BIS). In Europe, it is designated CW614N under EN 12164 (rod for free machining purposes). The alloys are closely equivalent in composition and performance.
If your drawing says 'brass' without a grade specification, free cutting brass (IS 319) is what most Indian manufacturers will supply by default. If you need a different grade, specify it explicitly.
Lead-Free Brass: When to Specify It
The European RoHS Directive (2011/65/EU) restricts the use of lead in electronic and electrical equipment. Annex III of RoHS includes a temporary exemption for lead in copper alloys used in certain applications, but this has been subject to revision and may affect future procurement requirements.
Drinking water regulations in many jurisdictions — including NSF/ANSI 61 in North America and Regulation (EU) No 305/2011 for construction products — also restrict lead in materials in contact with potable water. For these applications, lead-free brass (CW510L or equivalent IS specification) should be specified.
Lead-free brass is harder to machine than IS 319 — it has lower machinability ratings, produces longer chips, and requires more conservative cutting parameters. This is reflected in higher machining costs and longer lead times.
Dezincification-Resistant (DZR) Brass
Dezincification is a form of corrosion in which zinc selectively leaches from the brass matrix, leaving behind a porous, weakened copper structure. It occurs most commonly in hot water systems, and certain chemistries (high chloride, low pH) accelerate it.
DZR brass (CW602N) contains a small arsenic addition (0.02–0.15%) that inhibits the dezincification mechanism. It is widely specified for plumbing fittings, valves, and compression fittings intended for hot water service. UK Water Regulations and BS EN 12165 commonly reference DZR compliance for plumbing components.
Indian Standards for Brass (BIS References)
- IS 319:2021 — Free Cutting Brass Rods and Sections; specifies chemical composition, mechanical properties, and tolerances for CW614N-equivalent rod
- IS 291:2019 — Wrought Copper and Copper Alloy Plates, Sheets, Strips, and Foils; covers cartridge brass and other wrought alloys
- IS 407:1981 — Specification for Copper and Copper Alloy Seamless Tubes
- IS 4170:1984 — Naval Brass rods and sections
Choosing the Right Brass Grade
The selection depends on the application environment, regulatory requirements, and manufacturing process:
| Requirement | Recommended Grade |
|---|---|
| CNC turning, high volume, cost-effective | Free cutting brass (IS 319 / CW614N) |
| RoHS compliance or drinking water contact | Lead-free brass (CW510L) |
| Marine or seawater-exposed components | Naval brass (CW712R) |
| Hot water plumbing in dezincification-risk areas | DZR brass (CW602N) |
| Deep drawing or cold forming (not machining) | Cartridge brass (CW505L) |
| High-strength structural brass components | High tensile brass (CW721R) |
Frequently Asked Questions
What is the most common brass grade used in CNC turning?
Free cutting brass, standardised as IS 319 in India and CW614N under EN 12164 in Europe. Its 3% lead content gives it the highest machinability of common brass alloys, making it the default for CNC-turned components.
What is IS 319 brass?
IS 319 is the Bureau of Indian Standards (BIS) specification for free cutting brass rods and sections. It covers the composition (nominally 58% Cu, 39% Zn, 3% Pb), mechanical properties (minimum tensile strength, hardness), and dimensional tolerances for rod stock used in precision machining.
What is lead-free brass and when should I specify it?
Lead-free brass is a brass alloy with lead content restricted to below 0.1% (versus 3% in standard free cutting brass). It should be specified when components will be in contact with drinking water, when the end product falls under RoHS restrictions, or when the buyer's procurement policy requires lead-free materials.
What is dezincification and which applications require DZR brass?
Dezincification is selective corrosion of zinc from brass, leaving a weak copper sponge. It occurs in hot water plumbing and aggressive water chemistry. DZR brass (CW602N) contains arsenic additions that prevent dezincification and is required by UK and Australian plumbing regulations for certain fittings and valves.