Overview of Bronze
Bronze is a popular copper and tin-based alloy but includes other elements such as aluminum, zinc, silicon, manganese, and phosphorous. As such, the results often vary based on the preferred elements and their percentage.
The copper content in bronze makes it a more valuable alloy than brass. Bronze Age can be traced back to 3500 BC. It exhibits low metal-to-metal friction and offers excellent ductility. Bronze resists corrosion and has a high melting point, making it highly applicable.
Grades of Bronze
There are different alloys of bronze suitable for various applications depending on their composition. Here are the most common bronze alloys:
- Alloy 932: The bronze alloy 392 is a high-leaded bronze perfect for manufacturing bushings, washers, and other non-pressure components.
- Alloy 954: This aluminum bronze alloy is suitable for any working environment. Manufacturers use aluminum bronze alloys in applications, including industrial and mounting equipment.
Applications
Bronze metal sheets have a broad range of industrial applications due to their unique properties. Its typical applications include:
- Petrochemical equipment
- Cast bronze sculpture
- Automobile transmission pilot bearings
- Submerged bearings
- Boat and ship fittings
- Electrical connectors
Overview of Brass
Brass is a popular metal alloy consisting primarily of copper and zinc, which dates back to 500 BC. This copper-based material is the cheapest option compared to other alternatives and contains the highest zinc amount. Brass material has a low melting point, allowing excellent formability. The copper vs. zinc amount determines the strength and appearance of brass material. Higher copper content gives it a dull gold appearance, while higher zinc content gives it a bright gold look.
Grades of Brass
Brass is available in different grades due to its element composition. Below are some of the alloys of brass used in CNC prototype machining and part production:
- Alloy 260 (Cartridge Brass): It has remarkable cold working characteristics and is commonly used in producing parts used in fasteners, automobiles, hardware, ammunition, etc.
- Alloy 272 (Yellow Brass): The alloy 272 possesses a higher zinc percentage of about 33%, enhancing its weldability property making it ideal for industrial applications.
- Alloy 330: It is a highly machinable alloy with low lead element. Also, it is well-suited for cold-working because it has a low percentage of lead content. The brass alloy 330 is widely used in piping applications.
- Alloy 360 (Free-cutting Brass): The alloy 360 is the most used alloy of brass. It exhibits outstanding malleability and machinability properties, making it ideal for soldering and brazing applications. Manufacturers commonly use the alloy 360 for making fittings, fasteners, valves, etc.
- Alloy 385 (Architectural Brass): Its high structural integrity makes it perfect for parts used in architectural systems and construction.
- Alloy 464 (Naval Brass): This brass corrosion-resistant alloy is typically used in marine environments. It has high corrosion resistance and can withstand temperature changes. It also supports different processes like welding, soldering, bending, etc., making it suitable for various applications.
Common Application of Brass
Brass is a popular metal alloy with aesthetic and decorative benefits suitable for custom machining projects. Besides, its excellent workability and machinability characteristics make it an ideal material for different applications such as:
- Musical instruments
- Jewelry
- Plumbing fittings
- Electronics and electrical terminals
- Door trim
Overview of Copper
Copper dates back to around 3000 BC when it was first used. It is a naturally occurring metallic element commonly found in the earth. This non-ferrous metal is labeled Cu on the periodic table.
Copper in its pure state is more valuable and recyclable without compromising its quality. Its high electrical conductivity, thermal conductivity, machinability, microbial, and good corrosion resistance characteristics make it applicable in different manufacturing industries.
Grades of Copper
There are different grades of copper usually compatible with machining different parts and prototypes. Here are some of the common alloys of copper:
- Alloy 101: This alloy of copper lacks oxygen, making it an ideal metal for projects that demand outstanding conductivity and ductility.
- Alloy 110 (Electrolytic Copper): It has the highest electrical and thermal conductivity level. It also exhibits excellent formability and ductility.
- Alloy 122: It is quite similar to copper alloy 110. Its mechanical characteristics include superior machinability, weldability, and malleability.
- Alloy 145 (Tellurium Copper): It contains about 0.7% tellurium content. It exhibits superior machinability, high thermal and electrical conductivity,
Applications
Copper’s remarkable mechanical properties make it a suitable material for several applications in various industries. Here are some of them:
- Heat sinks and heat exchangers
- Architectural components
- Electric motors
- Telecommunication components
- Anti-biofuel components in submarines
Brass vs. Bronze vs. Copper: Material Comparison
| Property | Brass | Bronze | Copper |
|---|---|---|---|
| Element Composition | Copper (55-95%) + Zinc | Copper (80-90%) + Tin + Other Metals | Pure Copper (99%+) |
| Appearance | Pale yellow color, metallic luster | Reddish brown color, metallic luster | Orange-red color, metallic luster |
| Corrosion Resistance | Intermediate | Very Good | Very Good |
| Yield Strength | 95 to 124 MPa | 125-800 MPa | 33.3MPa |
| Tensile Strength | 338 to 469 MPa | 350 to 635 MPa | 210MPa |
| Thermal Conductivity | 109-121 W/mK | 24-108 W/mK | 210-400 W/mK |
| Electrical Conductivity | High (but less than copper) | Moderate (lesser than brass and copper) | Very High |
| Hardness | 65-95 BHN | 60-290 BHN | 60-95 BHN |
| Machinability | Good to Excellent | Fair to Good | Fair |
| Weldability | Good | Poor | Excellent |
| Melting Point | 900-940°C | 1085-1130°C | 1085°C |
Although these metals are similar in ways that make it easy to muddle them up, they differ in specific aspects. This section discusses the key differences between brass, bronze, and copper:
Element Composition
Copper differs from brass and bronze since it is the only natural metal among the three. It is a naturally occurring metal (non-ferrous) that is directly usable for several compatible machining processes. Meanwhile, brass and bronze are typical alloys made by combining elements.
Brass is an alloy primarily composed of copper and zinc. Its composition of elements may include aluminum, silicon, iron, and manganese. In comparison, copper and tin are the main Bronze content. Moreover, bronze can also contain elements like zinc, phosphorous, nickel, and aluminum.
Physical Properties/Appearance
The color of brass is quite different from that of others because it has a yellowish-gold or gold-like appearance. On the other hand, bronze and copper have similar reddish-brown color. However, copper has a distinctive pinkish-orange color compared to the dull gold shade of bronze.
Corrosion Resistance
Corrosion resistance property is another difference between brass vs bronze vs copper. Bronze develops a protective coat (mottled patina) that offers excellent corrosion resistance, especially seawater corrosion. Bronze can resist corrosion in salt-water environments better than the other two; hence, it is a perfect material for marine applications due to a higher degree of resistance to salt-water corrosion.
In comparison, copper forms protective coatings that allow it to exhibit impressive resistance to corrosion. Summarily, bronze provides the highest level of corrosion resistance, followed by copper, while brass comes last in the arrangement.
Strength (Yield and Tensile Strength)
Bronze is the perfect choice when your project requires superior metal strength. Bronze exhibits superior yield strength compared to copper and brass, with a 125-800 MPa range. The yield strength of brass ranges from 95 to 124 MPa, while copper has the lowest yield strength of 33.3 MPa.
In terms of tensile strength, alloys of bronze have tensile strength ranging from 350 to 635 MPa, allowing it to withstand metal fatigue. Then, brass is next in line with an ultimate tensile strength between 338 to 469 MPa, while copper offers a 210 MPa tensile strength.
Thermal and Electrical Conductivity
The difference in these metals’ thermal and electrical conductivity helps you decide the best one for your application. In terms of thermal conductivity, brass has the lowest thermal conductivity of 64 BTU/hr-ft²-ºf, followed by copper with 223 BTU/hr-ft²-ºf. On the other hand, bronze exhibits the highest thermal conductivity between 229 and 1440 BTU/hr-ft²-ºf.
Copper exhibits 100 percent electrical conductivity; hence, manufacturers calculate the conductivity of other metals relative to copper. Brass is 28 percent as conducive as copper, while bronze has about 15 percent. However, the low ratings of bronze could result from its alloying element composition.
Weight
The weight of brass vs. bronze vs copper is another significant difference. The weights of brass and bronze are very close, considering their densities. However, brass is better if your project requires a lightweight metal, and you must pick between bronze vs brass.
Brass has a density of 8720 kg/cu.m, making it the lightest of the three metals. In contrast, the density of bronze is about 7,400 to 8900 kg/ cu.m, while copper has 8930 kg/cu.m, making it the heaviest of the three metals.
Hardness
Following the values on the Brignell hardness scale, the score for bronze ranges from 40 to 420, while the score for brass is between 55 and 73. On the other hand, copper has a score of 35, being the metal with the least hardness among the three. However, bronze is susceptible to fracturing because it is more brittle.
Machinability
In terms of machinability, copper exhibits superior machinability than bronze and brass. Besides, copper machining is more flexible than both bronze and brass. It makes typical manufacturing processes easier to work with.
Bronze is less suitable for machining processes because of its rigidity. Manufacturers encounter several challenges in machining brass because it is the least machinable of them all. It is inflexible and not bendable.
Weldability
Copper, bronze, and brass are weldable metals—however, deoxidized and oxygen-free copper exhibits superior weldability. TIG and MIG methods are the standard methods for welding copper alloys.
TIG, MIG, and silver soldering methods are also compatible with alloys of brass. More so, metals with lower zinc content are more weldable than alloys containing lead. Although bronze grades without lead exhibit fair weldability, they crack easily under stress. Therefore, SWAM may be the perfect welding technique in such a situation.
Durability
The sturdiest and strongest material among these three is bronze. It doesn’t bend easily and exhibits high corrosion resistance, making it the most durable material. Although copper is a strong material, it is more flexible compared to bronze but hardly cracks or scratches.
However, brass is susceptible to splitting and cracking. Also, it exhibits lower resistance to corrosion than the other two.
Melting point
The lower a metal’s melting point is, the more formable it is. The melting point of brass is 927ºC, bronze possesses a 913ºC melting point, while copper’s melting point is 1085ºC. However, the high melting point of copper may hinder its formability.
Helpful Considerations in Choosing the Right Material for Your Machining Projects
Choosing the suitable metal for your machining project is critical to achieving high-quality machined parts. Below are helpful considerations for choosing between brass vs bronze vs copper:
General Usage
Brass is highly malleable, inexpensive, exhibits low friction, and is easy to cast. Hence, it is ideal for general applications. It is widely used for making decorative components like doorknobs and musical instruments, which people come in contact with regularly due to its low friction properties.
Bronze is the best choice for making parts for marine applications because of its saltwater corrosion resistance. On the other hand, copper is often used to make food flasks and food heaters.
Degree of Flexibility
Even though bronze, brass, and copper have impressive degrees of durability, their level of flexibility differs. Natural occurring copper provides the highest flexibility, conductivity, and ductility. Copper offers the highest flexibility with remarkable conductivity. On the other hand, brass and bronze exhibit excellent machinability.
Cost
The cost of each of these metals differs since several alloys are available. However, brass is the perfect choice whenever you need a cheap metal to fit your budget. Brass is inexpensive due to its high amount of zinc content. Bronze comes as the second most affordable, while copper is the most expensive one out of the three.
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Conclusion
This guide has provided a well-detailed discussion of the differences between brass vs bronze vs copper. Although these metals share similarities, they exhibit certain advantages over the others in terms of electrical/thermal conductivity, machinability, ductility, and strength. Therefore, consider these differences as you choose the suitable one for your project!
