Brass is, without a doubt, one of the most used materials on the planet. In fact, the probability that you will interact with the metal alloy somehow before even leaving your house is ridiculously high. Door knobs, musical instruments, furniture, taps, bathroom fixtures – you just name it. Even more interesting is that the use of brass material supersedes household use and has become a mainstay in many industries, including the rapid prototyping industry. In this brass material guide, we will examine some of these brass properties and uses in this article. Also, you will learn of the different types and grades of brass. There’s more. We will also overview some relevant tips for choosing a brass material for rapid prototyping.
Properties of Brass
Brass is a metal alloy that is made primarily of copper and zinc. The typical brass composition percentage is 67% copper and 33% zinc. Brass nowadays consists of several other metals in small proportions to further improve its properties. Some of these metals are arsenic, lead, aluminum, and silicon.
The good thing with brass is the proportion of the two major metal constituents – copper and zinc – can be varied depending on what the brass material is going to be used for. However, this also means the properties of brass are not universal, depending on the brass composition.
Some of the properties of brass justify its widespread use in the rapid prototyping and custom brass machining industry. Let us briefly consider these properties.
Brass is a highly malleable alloy. While this malleability is primarily because of copper, brass is more malleable than copper and zinc. This malleability is definitely a plus in the rapid prototyping and custom brass machining industry as manufacturers can easily draw the alloy into different forms and shapes. This logic also applies when using brass 3D filament.
One of the most desirable properties for materials in rapid prototyping and parts manufacturing is corrosion resistance. This makes all the sense in the world, too, as corrosion-resistant materials can retain their external integrity and appearance for a long time. Brass material is very resistant to corrosion. This is mainly due to the lack of iron in brass. Reports even suggest that brass resists galvanic corrosion from saltwater, which is far more corrosive than fresh water. This property comes in particularly handy with brass 3D filament.
Brass has a unique bright gold appearance. The brass composition plays a massive part in the eventual color of the brass material. Higher copper content confers a more reddish color, while more zinc means the brass material is more silver in color. The focus on the external properties of materials in rapid prototyping is at an all-time high. Manufacturers pay more attention to aesthetics now, and it doesn’t get much better than the bright golden appearance of brass material.
Another one of the more desirable properties of brass material in rapid prototyping is its ease of machining. It has great tool life, high feed rates, high ductility, and flexibility, which are all dreams of every machinist, especially with operations like brass 3D printing.
High tensile strength
Despite being very machinable and easy to form, brass material has high tensile strength. Experts even compare its tensile strength to that of mild steel. Parts made of brass material will be sturdy and strong, increasing their overall durability.
Excellent electrical conductivity
Brass is a very conductive metal, primarily because of copper. In case you didn’t know, copper is the second most conductive metal. Going along with the high electrical conductivity of brass is its good thermal properties. This ultimately means that brass is useful in components required to be good electrical conductors in high temperatures.
Types of Brass
There are different types of brass – over 60! Brass categorization depends on various factors, like crystal structure, zinc content, color, etc. However, the main differences between the different brass types are informed by their crystal structure.
Brass consists of two main metals – copper and zinc. Because these two materials differ in their atomic structures, they may combine differently, depending on the proportion of each content and the temperature of the combination.
Considering these factors, brass materials may have three different types of crystal structure. They are:
This type of brass has less than 37% zinc. In terms of microstructure, alpha brasses have face centered cubic crystal structures. They form a homogenous crystal structure. Because they are softer than other brass types, it is easier to cold work, bend, draw, and roll them. One of the most relatable alpha brass is the 70/30 brass that contains 70% copper and 30% zinc. This type of alpha brass is very corrosion-resistant and can be easily cold worked.
In machining, alpha brasses are used to manufacture bolts, rivets, fasteners, spring contacts, and many other machined parts.
Beta brass is higher in zinc content than alpha brass, containing more than 45% of zinc. This type of brass is the hardest and strongest of the three types. But it is not as ductile as its other two counterparts and can only also be hot worked or cast. Beta brasses form a beta structure crystal. They have a body centered cubic crystal structure in terms of microstructure. Beta brass is useful in manufacturing taps, antique items, and other materials with complex parts.
Another name for alpha-beta brass is duplex brass. As the name strongly implies, they are a combination of both alpha and beta brasses grain structures. They contain between 37% and 45% zinc. The balance between the alpha and beta components of duplex brasses hugely depends on the zinc content. The alpha grain structure will be more predominant the closer the brass zinc proportion is to 37%. Likewise, having the brass composition closer to 45% zinc means more of the beta grain structure.
Alpha-beta brasses have better cold ductility and hardness than alpha brasses. They are also cheaper and more common than alpha brasses.
One of the downsides, though, of alpha-beta brasses is dezincification corrosion. This is the leaching of zinc from copper alloys, leaving just the copper component of brass.
Alpha-beta brasses are useful in the manufacture of tap fittings, hinges, radiator valves, etc.
Available Grades of Brass
Brass itself is an umbrella term for a variety of metal alloys. Although the two main metals are always copper and zinc, the brass composition of these two individual metals may differ in terms of proportion. This is also why the properties of brass are not universal. Because of these variations, there are different combinations or grades of brass material. These grades have different uses in rapid prototyping.
This grade of brass is one of the most used industrially today. Alloy 260 is also known as 70/30 brass. This means it contains 70% copper and 30% zinc. Perhaps the primary reason for its widespread use is its high ductility. One can easily draw this grade into various shapes and forms without compromising its strength and toughness. Alloy 260 is also not as susceptible to dezincification corrosion as other brass grades. Also, it has good cold working properties.
Alloy 260 is vital in the manufacture of components of ammunition, automobiles, and various fasteners.
This grade is also known as Muntz Metal, named after George Muntz, its inventor, who developed the alloy for the lining of boat hulls. Alloy 280 is a brass grade containing 60% copper and 40% zinc. This grade is high-strength brass, and its very strong nature makes it essential in custom brass machining. It is particularly suited to the manufacture of marine and architectural components.
Alloy 360 is also referred to as free cutting brass because it is easy to cut and drill. The ease in cutting is due primarily to lead, which constitutes about 3% of the brass composition. Alloy 360 is the commonest brass grade in the industry – and for good reasons too! Despite being quite soft and ductile, it has incredible tensile strength. The implication of this is high ease of machining. So much so that it is the industry standard for machinability. Also, it is very resistant to corrosion and great for soldering and brazing operations.
Alloy 360 is one of the go-to brass materials in the manufacture of fasteners, fittings, and many hardware components.
This alloy has the nickname architectural bronze. Don’t be fooled, though; it is still brass. It has a relatively high percentage of zinc. Like alloy 360, alloy 385 is very machinable. This makes it a fan favorite among manufacturers in the rapid prototyping and custom brass machining industry. Its principal use is in the architectural industry to manufacture various components, but it is also handy and relevant among artists.
The brass composition of alloy 464 is as follows: 59% copper, 40% zinc, 1% tin, and minute amounts of lead. This unique composition confers very high tensile strength ratings on the metal alloy. Being stronger than many other brass grades in the industry affects its machinability to a reasonable extent.
Another angle to the unique composition of this brass grade is its corrosion resistance, even in saltwater. This property, in particular, has made it very useful in the manufacture of components that will be exposed to high moisture content, like most naval vessels’ components. This also explains its other name – naval brass.
Pros and Cons of Brass material in rapid prototyping
- Nice on the eyes, giving the final product an exquisite appearance
- A very machinable alloy
- Excellent corrosion resistance properties
- Brass has excellent electrical and thermal conduction properties
- Low friction properties
- Brass has good recycling properties
- Brass is prone to black tarnish and requires regular maintenance
- High zinc content may make the brass material susceptible to dezincification
- Stress cracks may appear after a while
RapidDirect’s CNC Machining Metals
There are many metals used for CNC machining. One of these metals or, more appropriately, metal alloys is brass. The use of brass in CNC machining is mostly due to many of its very desirable qualities, like its excellent electrical conductivity, good machinability, and low friction.
If you need information about brass materials for your CNC machining needs, RapidDirect is just the company you need. We also have experts that are always ready to help you out with all finishing or services that involve brass.
You can upload your design file and receive an instant quote, as well as DfM feedback. You are also free to reach out to us if you have any questions or need clarifications about brass use in CNC machining.
Tips for Choosing a Brass Material for the Best Application in Rapid Prototyping
Brass is a very useful metal alloy in sheet metal fabrication, rapid prototyping, CNC machining. One thing many don’t know about this alloy, though, is that it is an umbrella term for many different metal alloys. What do we mean? Many metal alloys contain the primary brass composition of copper and zinc but in varying proportions.
These variations in composition also mean variations in properties and, ultimately, use. Therefore, one cannot just pick any brass type or grade when rapid prototyping or manufacturing custom parts. Below are some tips that will help decide on the best brass material in rapid prototyping, rapid tooling, and custom brass machining.
Before deciding on a brass material, consider its appearance and the impact on your final product. Brass typically has a bright golden color, but this is very much subject to change depending on the copper and zinc composition. If your final product needs a more rosy appearance, consider going for a brass material with higher copper content. If you prefer a more silver appearance, then look out for brass materials with higher zinc content.
What is the final product’s desired strength?
Brass materials have different tensile strengths. While materials with very high tensile strength ratings will be stronger and sturdier, their ease of machining may be low. You just have to evaluate how strong you want your final product to be and try to find a balance.
Evaluate corrosion resistance
Corrosion is one of the banes of many metals – not brass, though. Brass materials typically don’t contain iron, making them quite resistant to corrosion. Some brass grades and types are more resistant to corrosion than others. For example, in the manufacture of ocean vessel components, brass with high corrosion resistance properties is a must. This also applies to materials that will hold saltwater.
Generally, brass has good machinability properties. So, many times, when a brass material is said to have poor machinability, it is usually relative to other brass materials. Now that we’ve established that, some CNC machining operations may require very easy machining. Yes, even at the expense of strength. Conversely, one may need to give up machining ease for additional strength. Understand all of these before making your decision.
Brass is one of the most used metal alloys in the world today. It is used in different industries, for different reasons, and in different ways. The industry we are most concerned with is the CNC machining and rapid prototyping industry.
As you must have seen in the article, many different factors go into choosing a brass material that will meet your custom brass machining needs. Even minor differences in brass composition may lead to significant changes in property. One cannot leave room for uncertainties in certain processes, like brass 3D printing. This makes it all the more important to be informed about all essential factors before dealing with brass alloy.