One has a historical period named after it, while the other is often associated with music. They have copper in common, but the difference between brass and bronze defines the best uses for these metal alloys.
Bronze Is Older and Harder
The ancient Sumerians are thought to have invented bronze around 3500 BC. A combination of copper and tin, and sometimes other additives like phosphorus, manganese, aluminum, or silicon, bronze melts at 950 degrees Celsius (1,742 degrees Fahrenheit). Its hardness made it useful for weaponry, and it resists corrosion, including corrosion from seawater. As a result, bronze enabled manufacture of weapons, armor, tools, and even parts for ships. Bronze conducts electricity and heat well. Bronze has a distinctive reddish color because of its high copper content. Although brass is more often associated with musical instruments, bronze’s hardness makes it suitable for bells and cymbals. Bronze is brittle, but not as brittle as iron. Bronze produces low friction against other metals and is sometimes used for bearings and springs.
Brass Is Younger and Shinier
Brass came along around 500 BC. Made from copper and zinc, brass melts at a lower temperature and is more easily bent and formed into a variety of shapes. Unlike tin and copper, zinc is almost never found in a pure state and must be derived from other materials, such as calamine, a mineral ore for zinc. Often brass melts at a lower temperature than bronze (900 Celsius, or 1,652 Fahrenheit) and flows when it melts. The addition of zinc gives brass a yellower color, closer to gold. Other additives vary the characteristics of brass; for example, adding manganese makes brass more corrosion resistant, while a higher zinc content makes it easier to stretch and bend. Brass is brighter and yellower, making it more attractive for some decorative applications like doorknobs. Corrosion-resistant brass is suitable for some plumbing fixtures. Brass is good for low-friction applications of metal to metal, like gears, doorknobs and locks, and some valves.
Manufacturing With Bronze and Brass
Both bronze and brass can be cast or molded; mass manufacturing processes such as cutting, stamping, heating, or molding can leave remnants of metal called “burrs” on manufactured pieces. These must be removed in a process called “deburring.” Manual deburring is a labor-intensive process, whereas automated deburring in a vibratory or tumbling deburring machine can yield more uniform finished parts. Care must be taken in selecting the correct type of machine and media—the additive pieces that create the friction to remove excess metal without damaging the part. Deburring also polishes metal.
The difference between brass and bronze can be subtle and depends on the amount and type of metal added to copper to produce the distinctive hardness and reddish color of bronze or the softer, more malleable, shiny golden color of brass.