Bronze is a versatile alloy group widely used in CNC machining for parts that require strength, corrosion resistance, low friction, and aesthetic appeal.
Composed primarily of copper and tin—with the addition of other elements like phosphorus, aluminum, or silicon—bronze alloys exhibit unique properties that make them ideal for both industrial and decorative applications.
In CNC machining, selecting the right bronze alloy is critical to achieving optimal performance, precision, and longevity. In this guide, we explore the top five bronze alloys used in CNC machining and where they are applied across industries.
1. C932 Bronze (SAE 660 / Bearing Bronze)
Overview:
C932 bronze, also known as SAE 660 or bearing bronze, is one of the most commonly machined bronze alloys. It contains copper, tin, zinc, and lead, providing excellent machinability and good wear resistance.
Key Properties:
- High load-carrying capacity
- Excellent machinability
- Good antifriction characteristics
- Suitable for lubrication-based systems
Common Applications:
- Bearings and bushings: Especially for moderate-speed and moderate-load conditions
- Pump components: Including sleeves and impellers
- Engine parts: Camshaft bearings and oil pump components
- Gear blanks and wear plates
This alloy is widely used in automotive, industrial machinery, and agricultural equipment, where moving components require both durability and machinability.
2. C95400 Bronze (Aluminum Bronze)
Overview:
C95400, or aluminum bronze, is a strong, corrosion-resistant alloy composed of approximately 85% copper, 10% aluminum, and small amounts of iron and nickel. It offers excellent strength and hardness, making it a preferred choice in heavy-duty applications.
Key Properties:
- High tensile strength (up to 90,000 psi)
- Excellent corrosion and erosion resistance
- Non-sparking, non-magnetic
- High resistance to fatigue and wear
Common Applications:
- Marine components: Propellers, shafts, and seawater piping
- Aerospace parts: Landing gear bushings and hydraulic components
- Oil & gas tools: Valves and pump housings
- Industrial tooling: Wear plates and guide rails
Aluminum bronze is especially effective in marine, oil & gas, and aerospace applications due to its superior resistance to saltwater corrosion and heavy mechanical loads.
3. C54400 Bronze (Phosphor Bronze)
Overview:
C54400 phosphor bronze, also known as “electric bronze” or “leaded phosphor bronze,” contains copper, tin, phosphorus, and a small amount of lead. It combines good strength with excellent fatigue resistance and electrical conductivity.
Key Properties:
- High fatigue resistance
- Excellent spring properties
- Moderate electrical conductivity
- Excellent wear resistance in dry and lubricated conditions
Common Applications:
- Electrical connectors and contacts
- Precision springs
- Washers and fasteners
- Musical instruments: Valve guides and slide tubes
Phosphor bronze is favored in electrical, electronics, and musical instrument manufacturing, where durability and stable mechanical performance under repeated stress are required.
4. C51000 Bronze (Tin Bronze)
Overview:
C51000, or tin bronze, is a high-performance alloy made from copper and 5% tin. It features excellent corrosion resistance, fatigue strength, and low wear rates under high-load conditions.
Key Properties:
- Excellent formability and toughness
- High resistance to corrosion and de-zincification
- Suitable for high-load, low-speed applications
- Non-sparking and safe for explosive environments
Common Applications:
- Valve stems and fittings
- Bushings and sleeve bearings
- Hydraulic components
- Industrial fasteners and electrical switchgear
Tin bronze performs well in chemical processing, heavy equipment, and hydraulic systems, where exposure to corrosive fluids or high mechanical pressure is common.
5. C86300 Bronze (Manganese Bronze)
Overview:
C86300, or manganese bronze, is a heavy-duty alloy composed of copper, zinc, aluminum, and manganese. It’s known for its high strength, toughness, and resistance to deformation under high loads.
Key Properties:
- Very high tensile and yield strength
- Excellent wear resistance
- Moderate corrosion resistance
- Limited machinability (requires sharp tooling and controlled feed)
Common Applications:
- Heavy equipment bushings
- Gear blanks and worm gears
- Bearing sleeves and thrust washers
- Winch parts and marine lifting components
Manganese bronze is widely used in construction equipment, mining machinery, and marine hardware, particularly where high impact resistance and mechanical durability are essential.
Why Bronze Alloys Are Ideal for CNC Machining
CNC machining of bronze metals offers several advantages over other manufacturing methods:
- Excellent machinability: Especially for leaded bronze grades like C932
- Tight tolerance capabilities: CNC systems can consistently achieve high dimensional accuracy
- Superior surface finish: Bronze alloys can be finished to a smooth, wear-resistant surface
- Low tool wear: Many bronze types are less abrasive than harder metals, extending tool life
Bronze’s machinability allows for complex part geometries, making it suitable for custom components across industrial and commercial markets. With CNC, you can produce everything from micro-bearings to large-scale structural components with repeatable quality.
Industries Using CNC-Machined Bronze Components
| Industry | Example Applications |
|---|---|
| Aerospace | Bushings, actuators, non-sparking connectors |
| Marine | Propellers, underwater brackets, shaft sleeves |
| Oil & Gas | Valve guides, seals, downhole drilling components |
| Manufacturing | Guide rails, wear strips, hydraulic components |
| Automotive | Bearings, fuel pump parts, transmission spacers |
| Electronics | Connectors, signal springs, grounding components |
Whether it’s corrosion resistance, fatigue performance, or mechanical strength, CNC machining services help unlock the full potential of bronze across high-performance applications.
Summary: Choosing the Right Bronze for CNC Projects
Each bronze alloy brings unique advantages to CNC machining. Here’s a quick recap:
| Alloy | Best Known For | Common Uses |
|---|---|---|
| C932 | Excellent machinability, bearings | Automotive, pumps, gearboxes |
| C95400 | High strength, marine resistance | Aerospace, marine, oil & gas |
| C54400 | Spring properties, conductivity | Electronics, precision components |
| C51000 | Corrosion resistance, fatigue | Hydraulic fittings, fasteners |
| C86300 | High load durability, impact strength | Heavy equipment, industrial bushings |
To ensure part longevity, performance, and accuracy, it’s essential to work with an experienced CNC machining service provider familiar with bronze machining strategies, tooling, and finishing techniques.
Final Thoughts
Bronze alloys continue to be critical in precision CNC machining thanks to their strength, machinability, and adaptability.
By selecting the right bronze type and using advanced CNC techniques, manufacturers can produce durable, high-performance parts for demanding industries.
Whether you’re prototyping a new bushing, scaling production of aerospace components, or developing corrosion-resistant marine parts, bronze machining offers both flexibility and function—with a timeless metallic finish.
