What is the Difference Between Copper, Brass, and Bronze Parts
What is the Difference Between Copper, Brass, and Bronze Parts?
Copper, brass, and bronze are three different metals used for a wide variety of parts and applications. These three have a lot of similarities, so it can be difficult to tell the difference, and understand which one is better for your project.
To start, brass and bronze are alloys that include copper. So it makes sense why you might think the metals are essentially the same thing. Copper is an element, but pure copper isn’t typically used to make copper parts.
That means, in most cases, copper, brass, and bronze parts are all slightly different mixtures of pure copper and a few other metals like tin, lead, and zinc.
Keep reading to better understand the differences between the three materials and choose what’s best for your parts and components.
The most important differences
You probably know that pure metals are rarely used for anything. Different elements are mixed together to form a metal alloy. This is done with high precision to enhance certain properties of the metal parts.
For example, a tiny amount of lead can be added to a copper alloy to improve the machinability of the metal. The differences between copper, brass, and bronze are because of the different elements added to the alloys.
Copper
As mentioned, copper is a pure metal. Pure copper (99.95% copper) is used for wiring, or applications where conductivity is a high priority. Even a slight drop in the purity can have a significant impact on the electrical conductivity.
Pure copper is a softer, malleable metal, so it’s great for wiring and sheet metal, but not as good for parts that need more durability. Copper alloys usually have a small amount of beryllium, tellurium, or lead to improve machinability and durability.
Copper can be used in a CNC mill, CNC turning machine, or a Swiss screw machine to manufacture parts. Because it’s a softer metal, it has a lower machining cost.
Copper is used for:
- Fittings
- Bolts
- Electrical contacts
- Bushings
- Bearings
- Fasteners
- Pump and valve components
Brass
Brass is one of the easiest metals to machine. Machined brass parts are durable, cost-efficient, and create a tight seal for fittings. Brass parts also have great heat and corrosion resistance.
Brass alloys are a mixture of about 65% copper and 35% zinc. Other trace elements like lead, zinc, and iron are added to improve certain characteristics.
Because of the added zinc, brass parts are significantly stronger than copper. Brass is also less expensive compared to copper. Brass parts don’t have the same conductivity as copper, so they’re less common in electronics, or systems where conducting heat is needed.
Brass parts are commonly used in applications in the engineering, plumbing, and steam industries because brass fittings offer a low friction coefficient and high corrosion resistance. Because brass is a harder metal, it’s more subject to cracking compared to copper.
Brass is used for:
- Fittings
- Gears
- Bearings
- Valves
Bronze
Bronze is a copper-based alloy that consists of varying amounts of copper and tin. Trace amounts of other metals, like aluminum, manganese, phosphorus, and silicon, are also found in bronze alloys.
The primary difference is the strength of the alloy. Bronze is stronger and more durable than copper and brass. Bronze can withstand more weight, and has a higher yield and tensile strength. Higher strength means that bronze parts are used in applications where parts are more subject to denting or wearing down. Like copper and brass, bronze is also a “no-spark” metal. And because it’s stronger, bronze is used for hammers, mallets, and wrenches that won’t spark when they’re struck against another metal.
Bronze is used for:
- Automotive fittings
- Bearings and bushings
- Cylinders
- Gears and sprockets
- Impellers
- Plates
- Pump and valve components
- Washers
How can you tell the difference?
The easiest way to spot the difference between copper, brass, and bronze parts is the color. But, depending on the alloy and secondary operations, the metals can look similar.
Most copper alloys have a reddish-brown color. Brass has a brighter yellow-gold appearance. And bronze is usually a duller gold or sepia color.
Choose the right metal for your project
Choosing the right metal for your part is critical. And with three different options that can look very similar, you need to know what to pay attention to. Here’s what you should keep in mind when deciding between these materials.
Copper has the highest flexibility and conductivity. That makes it better for parts that need to flex under pressure without cracking. And copper is best for parts that need to conduct heat or electricity.
Brass is often considered the most suitable for general applications. It’s malleable, easy to cast, relatively inexpensive, and low-friction.
Bronze is the hardest metal alloy, and best suited for saltwater and sea environments. Parts used in marine environments need to have high corrosion resistance. Higher durability and hardness also make it better for high stress marine applications.
Spex is an ISO 9001:2015 certified precision machine shop in Rochester, NY. We machine thousands of unique metal and polycarbonate parts every month for different industries around the world. Reach out to our team to see if we can help with your next project.
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What is a Metal Alloy?
June 11, 2022
What is a Metal Alloy?
You’ve likely heard of the term alloy, but what exactly does that mean? Metal alloys are used everywhere. From the tiny screws that hold eyeglasses together, to the frame of a skyscraper. Parts of the phone or computer you’re reading this on are metal alloys.
Most of the metal parts and structures you see are metal alloys.
In simple terms, a metal alloy is a specific mixture of metallic and nonmetallic elements. The elements used to make the alloy are melted down into a liquid, mixed together, and then cooled to resolidify. This process is sometimes called alloyization.
Why are metal alloys used?
You’re probably familiar with most of the metallic elements in the periodic table. Metals like aluminum, iron, copper, gold, and titanium are naturally occurring elements. You might be surprised to learn that the majority of the elements are classified as metals.
Not every element is naturally occurring, but for the ones that are, you can dig them up from the ground, and process them into metal bars or plates.
Alloys are used because in most cases, a pure, single metallic element isn’t ideal for parts or building structures.
Adding other metal or nonmetal elements improves specific properties of the alloy. The strength, durability, color, flexibility, machinability, and corrosion resistance can all be significantly improved.
For example, adding a small amount of lead or sulfur to alloys improves the machinability of metals. And adding carbon increases hardness, but decreases machinability.
Because the percentages of the elements used in alloys can be easily adjustable, there are 100s of different alloys–each having specific pros and cons.
What are the most common metal alloys?
Metal alloys usually have a base metal that makes up the majority of the composition. In addition to the base element, there are common additions. You’ll see numbers that are used to identify the different alloys, like 303 stainless steel, or 2011 aluminum.
Here are a few of the common metal alloys used in precision machining.
Stainless steel alloys
Stainless steel is one of the most commonly used alloys. Stainless steel alloys have an iron base, usually around 25-35%. Another 20-30% of chromium and nickel are added to the iron to improve corrosion resistance and prevent the metal from rusting.
The remainder of stainless steel alloys are made up of 7-10 other elements. Stainless steel alloys can contain smaller amounts of sulfur, silicon, copper, carbon, nitrogen, and manganese. These elements can make the alloy harder or softer, improve machinability, and increase the corrosion resistance.
Steel alloys
Steel is another commonly used metal alloy that’s incredibly diverse. Steel alloys are made with 95-99% iron. Surprisingly, pure iron isn’t useful for parts or building materials because it’s soft and brittle. It’s easily bent and malleable, until other elements are added to create a steel alloy.
Adding a small amount of carbon to the iron makes it hard, and usable for durable parts and building materials. But, adding too much carbon makes the alloy more difficult to machine. To improve machinability, elements like sulfur and lead are added.
Aluminum alloys
Pure aluminum is a great material, but it lacks strength and durability needed to make usable parts. To increase the tensile strength, zinc and manganese are added to aluminum alloys. Chromium can also be added to increase the corrosion resistance of the aluminum parts.
Most aluminum alloys are 85-95% aluminum. This keeps the benefits that aluminum offers–mainly the excellent strength-to-weight ratio.
Copper alloys
Copper is one of the best conductors of electricity and heat. So, pure copper (99%+) is used for electrical wiring. But, copper is soft and flexible, so copper alloys are used for parts that need more strength and durability.
Copper has a wide variety of alloys that include different copper alloys, brass, and bronze. Free machining copper is 97-99% copper, and small amounts of lead, beryllium, cobalt, and/or tellurium.
Brass alloys are a combination of copper, zinc, and lead. The zinc adds hardness and durability to the parts.
Bronze alloys are a mixture of copper and tin. Bronze is even harder than brass alloys, so it’s used when more durability is needed.
Learn about the difference between copper, brass, and bronze.
Nickel alloys
Nickel is a metal that’s added in smaller amounts to stainless steel alloys. Nickel offers some of the best corrosion resistance. It’s also more expensive than most other metals. Nickel based alloys are often considered super alloys, because of the high corrosion resistance and strength.
Monel is a nickel-copper alloy that contains around 65% nickel and 30% copper.
Inconel is a nickel-chromium alloy that’s roughly 70% nickel, 15% chromium, and 8% iron.
Hastelloy is a nickel-chromium-molybdenum alloy. It contains 55-60% nickel, 15% chromium, and 15% molybdenum.
Those are some of the most common metal alloys used for precision machined parts. But, the properties of the alloy can be changed by adding 0.2% of a certain element. This makes the combinations and applications of different alloys limitless.
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How to Choose the Right Material for Your CNC Part
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