Mastering Brass CNC Machining: Techniques, Tips, and Innovations

From plumbing fixtures to electrical components and bearings, brass is a staple of our everyday lives. This copper-zinc alloy is known for its excellent machinability, superior corrosion resistance, and high degree of strength, ductility, and malleability, making it a go-to in many applications.

Its machine-friendliness and mechanical properties make brass an especially suitable material for computer numerical control (CNC) machining. Recent research has shown that brass is capable of far more intensive machining than we previously thought possible. 

In this brass CNC machining guide, we’ll look at the leading advantages of working with this material. We’ll evaluate some key machining techniques, as well as the main challenges and best practices associated with brass CNC machining. We’ll also show you which applications use brass the most and where CNC brass machining is heading in the future.

Understanding Brass: The Ideal Material for CNC Machining

Many of your brass CNC machining operations will depend on the material properties of the exact brass alloy being used. Therefore, it is essential to understand brass’s material composition to determine how you’ll use it for your application.

Here’s a look at why brass lends itself to precision machining so well and what material properties are responsible for its excellent performance. 

What Makes Brass Perfect for Precision Machining?

Brass has many mechanical properties that make it a good choice for CNC machining. A few of them are: 

• Low friction. Its exact friction coefficient will vary with several factors, but brass generally creates relatively little friction. The result is minimal heat generation during machining, making fabricating parts with intricate or tight-tolerance designs easier.
• Dimensional stability. Brass has a relatively low coefficient of thermal expansion (CTE), allowing it to maintain tight tolerances and deform minimally during precision machining. This enables tighter tolerances suitable for marine and industrial applications.
• Ease of cutting. Brass’s constituent components are relatively soft, making the alloy easier to cut than harder materials such as steel. Brass stock is, therefore, highly machinable, creating little tool wear in the process. 

While other material properties, such as high strength and malleability, corrosion resistance, and electrical conductivity, make it useful for a wide range of applications, its softness and stability make brass parts easy to precision-machine, even with the most demanding specifications. 

Exploring Various Brass Alloys and Their Applications​

Brass is primarily a copper-zinc alloy, but many other elements can be added to modify its material properties. Lead, aluminum, tin, iron, and manganese are a few elements that may comprise some brass alloys to alter their machinability, strength, or corrosion resistance, but simply adjusting the concentration of copper or zinc is often enough to achieve the desired result. The main types of brass alloys are: 

• C360, also known as free-cutting brass, is typically made from approximately 3% lead, 30%+ zinc, and 60%+ copper, along with trace amounts of other materials. This is the most common brass alloy, known for its high strength and machinability, and is useful for soldering and brazing applications. C360 is often used for hardware components such as fasteners, screws, and valves, as well as many other industrial equipment components. 
• C260, or cartridge brass, has a higher concentration of copper and lower concentrations of zinc and lead. It, therefore, has favorable cold-working properties and superior ductility and malleability, so it’s often used for ammunition, hardware, plumbing, and electronic applications. 
• C46400, or naval brass, has a roughly 40% concentration of zinc, nearly 60% copper, and less than 1% tin and lead. This gives it a greater degree of corrosion resistance and strength, making it suitable for marine applications. 

While many brass alloys are classified simply by their zinc and copper concentrations, these differences are enough to create a wide range of material properties. The result is a highly versatile and machinable material, useful for a variety of high-quality brass CNC machining products. 

Essential Techniques in Brass CNC Machining

Once you’ve chosen the alloy with the suitable material properties for your processes, you still need to consider the machining techniques needed to fabricate your part. The key factors include tool selection, machining parameters, and the desired surface finish of your final product.

Optimizing Cutting Parameters for Brass​

CNC machines are programmed to fabricate parts based on their design and multiple machining parameters. A few cutting parameters include: 

• Tooling method: Drilling, turning, milling, and more
• Spindle speed: How fast the tool rotates
• Feed rate: The speed at which the tool advances into the material
• Cutting depth: How far the tool presses into the stock with each pass
• Rake angle: The angle between the tool face and a perpendicular plane to the cutting direction

These parameters are critical not only for machining the part according to specs but also for maintaining your CNC machine’s operability. For example, long, ribbon-shaped chip formation could damage the machine, resulting in costly downtime and repairs.

Adjusting the feed rate, cutting depth, or rake angle can control chip formation, extending the life of your tool and CNC machine. Spindle speed and cutting depth can also impact the amount of friction generated during the cutting process, so reducing these parameters can help with heat management issues. 

How to Enhance Surface Finishing

Brass has a natural aesthetic appeal, and it’s often used in industrial applications where aesthetics aren’t a priority. That means many brass CNC machining products require no surface finish at all — but when it is needed, the right finish is essential for the final performance. The most common surface finishing techniques are:

• Polishing, where any ruptured materials are removed from the part’s surface, creating greater smoothness and closer adherence to the desired tolerance
• Plating, where the part is immersed in an aqueous electrolyte and electrically charged next to another metal node, causing the other metal to transfer onto the surface, forming a thin layer across the brass part
• Powder coating, where powdered material is sprayed across the part and then typically heated to ensure proper adhesion

These surface finishing techniques do more than enhance a part’s visual appeal. For example, polishing can improve corrosion resistance by removing minor imperfections where oxidizing reactions could occur. Powder coating and plating can also affect mechanical properties such as wear resistance and hardness, impacting the life and performance of the final product.

Tool Selection: Choosing the Right Tools for Brass Projects

Choosing the right tool for your brass CNC machining products involves more than simply determining the cutting method. Factors such as blade coating, cutting speed, cutting angle, and tool geometry can all impact the efficiency of your brass CNC machining processes, affecting both the lifetime of the tool and the final condition of your part. 

For example, burr formation can cause rough edges and higher localized stress concentrations, eventually leading to damage or failure. You can minimize burr formation and wear by choosing a higher cutting speed, a positive rake angle with a relatively low cutting depth, and a carbide blade finish that is best suited for CNC machining brass parts. 

Overcoming Challenges in Brass Machining

While the material is well-suited for precision-machining applications, achieving high-quality brass CNC machining still comes with its share of challenges. Some common brass CNC machining barriers and their solutions are:

• Tool wear. The wrong cutting speed, angle, or depth can place excessive wear on your tools, increasing power requirements and shortening their lifetime. A worn tool can also damage the brass part, so select a high cutting speed with a positive rake angle for softer materials, like brass.
• Chip control. Slower feed rates and more shallow cutting depths produce smaller, more uniform chips, which are less likely to damage your machine. If you’re concerned about chip control, consider reducing your feed rate and depth.
• Burr formation. Multiple factors cause burr formation, so try to optimize cutting speed, feed rate, and depth. Adding coolant can also reduce friction and subsequent burrs while managing heat generation at the same time.
• Maintaining tight tolerances. Some intricate parts require tight tolerances, which can be difficult to maintain throughout the machining process. The first step is a design for manufacturability (DFM) process that ensures the required fabrication is feasible, but polishing can also help remove inconsistencies that could impact the part’s tolerance.

With so many factors to consider, working with a partner specializing in CNC machining services can be a game-changer. Industry experts are familiar with the challenges that CNC machining can present, and they’re equipped with the knowledge and tools needed to resolve them. If you need high-quality brass CNC machining, consulting an expert can help.

Applications of Brass CNC Machined Parts

Its wide range of material properties and easy machinability make brass an ideal material for many applications. The most common ones involve electronics and fluid handling due to brass’s superior conductivity and corrosion resistance, respectively. However, its mechanical properties and aesthetic appeal make it a solid choice for many industrial components and even some popular consumer goods.  

Electronics and Electrical Industry

As a copper-based alloy, brass has excellent electrical conductivity. That makes it ideal for electronics, so brass is often used in electronic components such as: 

• Connectors and terminal studs 
• Printed circuit board (PCB) fasteners
• Switch components
• Plugs and sockets
• Relays and antennas

In addition to its electrical conductivity, brass is a good heat conductor. That makes it a suitable material for heat sinks, preventing electronic components like laptops from overheating. 

Plumbing and Fluid Handling

Its superior corrosion resistance makes brass a go-to material for wet environments, especially in marine applications. Brass is often found in:

• Plumbing components, such as pipes, fittings, fixtures, and bushings
• Naval subsystems, such as propellers, shafts, and rudders
• Fluid transfer systems, such as radiators, heat exchangers, and pumps

Typically, C46400 or naval brass is the alloy of choice for marine applications. The extra tin adds corrosion resistance and antifouling properties to the brass. This enables it to endure corrosive saltwater environments, or those in the oil and gas industries, where hydrocarbons could damage other materials. 

Industrial Equipment

Brass’s low friction and wear resistance make it useful for industrial components. It’s also highly machinable, malleable, and ductile while maintaining its mechanical strength, so brass can easily be formed into intricate geometries while retaining its toughness and durability. Some common brass industrial components are:

• Bushings, bearings, and wear plates, due to brass’s minimal friction
• Connecting rods and shafts, because of its tensile strength and durability
• Gears and cams, because of its machinability and wear resistance

Brass’s toughness also gives it good pressure resistance, making it ideal for high-pressure applications. Therefore, it is a staple in pump subsystems and components, such as casings, impellers, and sprinkler systems, especially since it’s corrosion-resistant.

Medical Equipment 

The copper in brass gives the alloy antimicrobial properties, which are highly beneficial for the healthcare industry. Much research has been done regarding the exact mechanism and conditions behind brass’s antimicrobial properties. Still, its benefits are established enough to make it the material of choice in many medical operations. In addition to doorknobs, bathroom fixtures, and other surfaces, brass is a key material in: 

• Gas delivery systems, such as valves, gaskets, or fittings
• Implantable devices, such as screws, pins, and fasteners
• Electronic devices, such as implantables, for signal transmission

When manufacturers select brass for their medical applications, they must consider the alloy’s composition. Some brass alloys contain larger amounts of lead than others, and since lead can be harmful if ingested, only those with minimal lead concentrations are appropriate. Working with an expert who specializes in CNC machining in the medical industry can help you determine which alloys are best for your application.

Consumer Goods

In addition to its mechanical properties, brass has a natural aesthetic appeal. From copper-rich brass’s reddish hue to zinc-rich brass’s golden shine, this material is often sought out simply for its natural beauty. 

Its appeal makes brass commonplace in many consumer goods, such as jewelry, watches, and home decor. Brass’s workability also lets craftspeople use a CNC brass engraving machine to add a personal touch to luxury items, and its acoustic properties make it an excellent choice for many musical instruments.

Future Trends and Technological Advancements in Brass Machining

Brass is already a core component of many applications, but some advancements may take the material to heights higher than previously thought possible. A few trends in brass machining that we’re seeing are:

• AI for CNC machining, to optimize tool paths and machining parameters for maximum efficiency and productivity
• Automation, to reduce errors while increasing throughput
• Sustainable practices, to minimize material waste 

Another key innovation in brass CNC machining is the development of environmentally friendly brass alloys with superior properties. Researchers are conducting extensive reviews on exact compositions, but the goal is to improve not only the efficiency of brass CNC machining but also to build a more sustainable, higher-quality product.

Trying Brass CNC Machining With TFG USA 

From everyday appliances to sophisticated marine or electronic components, brass is a fixture in products of all shapes and sizes. It’s cost-effective, versatile, and aesthetically pleasing — and it’s an excellent choice as a CNC stock material. 

Manufacturers wishing to make the most of their brass CNC machining should, however, consider issues such as tool wear, burr formation, chip control, and the desired surface finish and application. A trusted brass CNC machining service can help establish the best practices needed to build each part according to specs and desires.

TFG USA specializes in custom manufacturing, including brass CNC machining. We offer tailored solutions that meet our clients’ unique specifications and requirements, and our team of experts specializes in CNC machining processes for a wide range of materials. 

Our state-of-the-art facility also features an array of leading-edge machining equipment for producing high-precision components that adhere to the strictest tolerances and quality standards. Reach out to learn more about how TFG USA can take your CNC machining to new levels.