All About Brass as a Manufacturing Material

What is Brass?

Brass is a workable, machinable, antibacterial, and anti-biofouling material. As briefly covered in our intro, brass is a metal alloy of copper and zinc that typically has a golden-yellow color but if the alloy has a lot of copper in it, it could sport a reddish hue. This type is called “red brass.” The exact quantities of copper and zinc (or other alloying elements) in the brass will determine its type and properties. Lead in brass will improve its corrosion resistance and machinability, and including iron will make it harder and easier to forge.

Types of Brass

There are many brass alloys and they differ in their elemental makeup. Here are some of the most commonly used ones.

1. Alloy 260 (Cartridge Brass): This has around 70% copper and 30% zinc with impurities. This alloy has excellent hot formability and is readily cold-worked.

2. Alloy 280 (Muntz Brass / Muntz Metal): This brass alloy contains approximately 60% copper and 40% zinc, as well as trace amounts of iron. A common application for Muntz metal was as a less expensive replacement for the copper sheeting formerly placed on boat hulls to prevent the growth of sea organisms such as barnacles on the hulls.

3. Alloy C360 (Free Machining Brass): This brass alloy contains approximately 60% copper, 35.5% zinc, up to 3.7% lead, and trace quantities of iron. This alloy is one of the easiest materials of all the brasses to machine and is classified as having a 100% machinability rating. It’s commonly used for parts like gears and bushings.

4. Alloy 385 (Architectural Bronze): Despite being called bronze, 385 brass has around 59% copper, 42% zinc, and up to 3.5% lead in it. This mixture makes it more machinabile and formabile, which is why it’s popular in architecture for aluminum extrusions. 

5. Brass 464 Marine Grade (Naval Brass): This brass alloy contains approximately 59% copper, 40% percent zinc, and 1% tin, with a small amount of lead. The combination produces a metal with exceptional corrosion resistance to seawater. Applications can include the various fittings found on the deck of a boat

Brass Applications

Brass is used in many industries because it’s so easy to work with, corrosion resistant, and has antibacterial properties. It can be made into many products, from bullet cartridges, gears, tools, valves, and pipes and fittings, to door handles and hinges, marine engines, and even musical instruments.

Brass Advantages

Brass has many advantages. In addition to being one of the easiest materials to machine (free-machining brass has an 100% machinability rating), it also has a low coefficient of friction (in layman’s terms, its surface is very smooth and slippery, which makes it great for parts that need to slide against each other without wearing down quickly). The copper content in brass can kill certain types of bacteria, making it the go-to for things for high-touch surfaces like door handles. It’s also used in marine industries thanks to its biofouling properties, meaning that algae and barnacles won’t grow on it. 

Brass Disadvantages

Brass’s main disadvantage is that it’s prone to tarnishing; if it’s not properly maintained, it can form unsightly blackish stains due to oxidation. To prevent this, many coat the material with a clear lacquer. It’s also non-hypoallergenic (you can thank the copper and zinc for that) and can cause some skin irritation to people with sensitive skin. Again, treating it with a lacquer coating could prevent this. Finally, its high copper content makes it more expensive than other metals (copper is notoriously pricey). 

Maximum Operating Temperature of Brass

Table 2 below lists the solidus temperature (melting onset) and the liquidus temperature (melting completion) for some common grades of brass:

How Strong is Brass?

Brass is quite strong and durable but the level of its strength depends on its composition and the type of heat treatment it has gone through. When naval brass is cold drawn and annealed, it gets a tensile strength of 580 MPa which is impressively as high as some steel grades. Brass that has been heat-treated is strong enough to be used for valve bodies that need to withstand high pressures.

Is Brass Safe to Use?

Yes, brass is safe to use for general engineering applications but is not recommended when coming into contact with acidic food (pH < 6). Brass is toxic to some microscopic organic life due to the negative effect of copper ions on various microscopic living organisms. Brass can also prompt an allergic reaction in persons with skin sensitivity. 

Copper vs. Brass vs. Bronze

All three of these are commonly referred to as “red metals.” Brass and bronze contain copper as their main element. Brass contains zinc as the main secondary element, while bronze typically has tin. Bronze is especially resistant to corrosion from seawater whereas brass has excellent low-friction capabilities. Copper is great for electrical applications like wiring or busbars due to its high conductivity.