The process of CNC machining a part often varies depending on the metal or metal alloy you are working with. Brass is no different in that manner, however, there are some key differences that separate it from other possible selections. Overall brass is considered highly machinable, but that does not mean it is a great choice for all applications. Today we take an in-depth look at machining brass to help you decide if it should be your metal of choice.
COMMONLY MACHINED BRASS PARTS
Brass has a wide variety of real-world applications. However, its composition has some disadvantages that may mean its not suited for your specific application. The following is a small list of the most common brass components.
- Valves
- Nozzles
- Bearings
- Knobs
- Hinges
- Fluid Fittings
- Plumbing
- Various Electronic Components
- Some Medical Components
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IS BRASS RIGHT for MY PROJECT
Like any project, there are layers to answering which material is the best for your specific part. To start, you should consider machinability, durability, corrosion resistance, thermal properties, etc. Each one of these factors are critical to helping you select the best materials for your part. If you need some assistance, we’ve discussed material options for CNC machining at length in the past.
If you are leaning toward using brass then you should carefully consider all the benefits and disadvantages before selecting it as the material for your project.
Benefits of Using CNC Brass Parts
Brass is made up of mostly copper and zinc. These metals can then be combined with other metals like silicon, tin, lead, aluminum and iron. This produces brass alloys with unique characteristics and enhanced properties. Some of these enhanced properties include:
- Machinability – Most brass contains lead or other soft metals that make it one of the easiest materials to machine, when compared to steel, titanium, or other hard metals.
- Corrosion Resistance – Brass comes in different alloys, such as ones with tin, which can produce a resistance to corrosion from saltwater. Other alloys have various levels of corrosive resistance, which can actually become a disadvantage as well.
- Finishing Options – A brass part can be used right off the CNC machine. Meaning you don’t have to spend extra production time on finishing. Additionally, there are a wide range of surfaces and finishes that can be applied to suit your needs as well.
- Durability – Even though brass is easily machinable it is still pretty hard. This makes it more durable than metals like aluminum or copper. Which means it will hold up better in more stressful environments over prolonged periods of time.
- Tolerances and Seals – Brass can be manufactured with a very small tolerance making it a solid choice when part accuracy is key. It also has the ability to hold a tight seal in fittings. This allows for a more secure and strong structure when attaching brass parts to other components.
Disadvantages of Using Brass Parts
Unfortunately brass isn’t a perfect metal for all applications. It has it’s share of disadvantages that can ultimately make it the worst choice for a part. Before you make your final decision you should consider the following:
- Toxicity – As mentioned before some brass contains lead. This makes it unfit for use in some medical and other applications.
- Weakness – Brass is pretty durable overall, however, it lacks the durability or harder metals like steel and titanium. Meaning it’s not the best choice if it’s to be used in a high stress environment over long periods of time.
- Susceptible to Corrosion – Though many brass alloys are touted for corrosive resistance to salt water and other mild environments, it can corrode in harsher environments or from exposure to acids, ammonia, amine, and more. If you are looking for the most corrosion resistant you should consider stainless steel or even aluminum.
- Cost – Brass on average tends to be more expensive than some of the other common CNC materials such as steel or aluminum. If you’re intending to keep the cost of your part down, brass may not be your first choice.
- Appearance – Due to its composition, brass tends to tarnish easily. This will lead to the appearance of patina and/or a general dullness. This means brass often is not the best for use in visual applications.
Types of Brass (Brass Grades) for CNC Machining
C360 - Free Machining Brass
Free machining brass, also known as C360, alloy 360, 360 brass, or free cutting brass. It consists of approximately 60-63% copper, 33%–37% zinc, 2.5%–3% lead and 0.35% iron. It remains one of the most versatile and commonly used grades of brass due to its excellent machinability. However its composition leaves it susceptible to corrosion from acids.
C230 - Red Brass "Nordic Brass"
Red brass is composed of 85% copper and 15% zinc. Though it only has moderate strength it has a wide variety of uses such as water pipe service lines. This is largely due to its anti-rust properties.
C220 - Commercial Bronze
Despite the name, Commercial Bronze is considered a brass alloy due to its high copper composition. It is composed of 89-91% copper, with .05% lead or iron and the remainder zinc. It is often used in architectural parts such as, lighting fixtures, kick plates, hardware, push plates, and weather stripping.
C464 - Naval Brass
Making Your Final Decision
Now that you have a complete understanding of the types of brass, its pros and cons, and the various options available, you can truly decide if it is the best material for your project. Remember, while CNC machined brass parts are used in a wide variety of applications, ultimately, the specific requirements for your final part should help you make your selection.
If you have trouble deciding or need assistance with a CNC machining service, please request a quote and a member of our team will be happy to assist you.
