Bronze and copper are materials often considered for their strength, conductivity, and aesthetic appeal, hence, their wide application for thousands of years in part manufacturing. However, weight can also be critical in choosing the better option.
When weight is key in material selection, part manufacturers rely on the lighter material that can still meet other technical project requirements. This post will discuss how the weight difference is formed and answer, “Which is lighter—bronze or copper?”
Table of Contents
What is Bronze?
Bronze is a copper alloy with tin as the primary alloying element. It can also contain other elements like aluminum, silicon, and nickel, which are sometimes added to achieve specific properties like corrosion resistance and improved surface hardness.
The material’s composition is 88% copper and 12% tin. However, sheet metal fabrication and CNC machining services need to know that the ratio can change depending on the presence of other alloying elements.
The density of the material is a huge contributor to this article as it is a measure of its weight. Bronze density ranges from 7.4 – 8.7 g/cm³, making it heavier than some pure metals. However, many sheet metal fabrication services will recommend it for structural and artistic applications.
Bronze’s melting point ranges between 950°C and 1050°C, and it also depends on the presence of other alloying elements. It has a high tensile strength, making it ideal for applications requiring resistance to wear and fatigue.
Lastly, it is highly corrosion-resistant, making it a material of choice for many CNC machining and metal fabricating processes looking for an effective material in marine environments. The protective patina on the surface protects against further degradation.
Pros of Bronze
- Bronze’s strength and hardness make it resistant to wear and fatigue
- It is resistant to corrosion, particularly from saltwater.
- Bronze has a visually appealing golden-brown hue that deepens with the patina’s development.
- Bronze is relatively easy to cast and machine, which has led to its wider use in CNC machining and metal casting.
Cons of Bronze
- Bronze is heavy due to its density
- Bronze’s price depends on its copper content, making it more expensive than other metals, especially during periods of high copper demand.
- Although tough, certain bronze forms, especially those with high tin content, can be brittle.
What is Copper?
Copper is a naturally occurring metal with excellent electrical and thermal conductivity. It has been used for years in electrical wiring, plumbing, and coinage. Compared to most alloys, copper is softer and more ductile.
Copper has a density of 8.96 g/cm³, which makes it heavier than bronze. However, it is more popular because it is one of the best conductors of electricity and heat, hence its broader use in making electrical wiring and electronic components.
Copper is highly ductile and can be drawn into thin wires without breaking. Furthermore, its malleability allows it to be easily shaped and formed into various products. In addition, it has a high melting point, at approximately 1085°C (1985°F), giving it an operational edge.
Copper is resistant to corrosion, especially in dry environments. However, when exposed to moist air or saltwater, it oxidizes to form a green patina (copper oxide).
Pros of Copper
- Copper is unmatched in electricity and heat conductivity
- Copper’s ability has high ductility and malleability
- It has natural antimicrobial properties
- Copper is highly recyclable, with minimal degradation in quality
Cons of Copper
- Copper is quite dense (8.96 g/cm³), making it heavy
- Copper can be expensive compared to cheaper alternatives like aluminum
- It is resistant to many types of corrosion, although not impervious
- Copper is softer than bronze, which makes it prone to scratching, denting, and general wear.
Bronze vs Copper: Which is Lighter?
After reading the bronze vs copper comparisons based on their different properties, the density shows that bronze is lighter than copper. Copper has a density of 8.96 g/cm³, while bronze’s density ranges from 7.4-8.7 g/cm³, depending on the alloy composition.
The difference in density and weight is because the atomic packing efficiency changes when copper is alloyed with tin to form bronze. Pure copper is packed in a face-centered cubic (FCC) structure, but adding tin or other alloying metals to form bronze changes this packing arrangement.
Loosely arranged atoms also mean higher interatomic spacing between atoms, reducing the number of particles per unit volume. As a result, the mass per unit volume of bronze is lower than that of copper.
Given these numbers, bronze is slightly lighter than copper. However, the difference in density is marginal, meaning that in most practical applications, the weight difference between similar-sized pieces of bronze and copper would be negligible.
Conclusion
Bronze is lighter than copper due to its lower density. However, the difference is minimal on average. Therefore, a project’s choice between bronze and copper centers more on properties like strength, conductivity, and corrosion resistance rather than weight alone.
Bronze offers better durability, wear resistance, and corrosion protection, while copper excels in projects that require conductivity and malleability. Ultimately, the material selection comes down to balancing these properties against the specific needs of your project.
