CNC Machining Copper Bushing: Alloys, Tips, and Manufacturing Process

Copper bushings—also known as plain bearings or sleeve bearings—are essential components in industrial machinery, marine equipment, hydraulic systems, pumps, and heavy-duty rotating equipment. They reduce friction between moving parts, support rotating shafts, and ensure smooth, reliable operation. With CNC Machining, manufacturers can produce high-precision copper bushings that meet tight tolerances and demanding performance requirements.

At EMAR, we specialize in custom CNC machined copper bushings, from simple cylindrical sleeves to complex flanged designs. Our team leverages extensive experience in machining bronze, brass, and other copper alloys to deliver precision parts on your schedule. For any questions about machining copper components, call us at +86 18664342076 or email sales8@sjt-ic.com.

What Is a Copper Bushing?

Copper bushings (also called copper alloy bearing sleeves) are cylindrical components with no moving parts. They rely on a sliding action and are often self‑lubricating or externally lubricated. Copper bushings are used in rotating, sliding, reciprocating, or oscillating motions. Standard configurations include:

• Cylindrical bushings (plain sleeve)

• Flanged bushings (integrated flange for axial load support)

• Thrust washers and flanged thrust washers

• Sliding plates

• Split bushings for easy installation

Custom designs can include features such as holes, grooves, notches, tabs, and specific oil‑groove patterns.

Copper Alloys for CNC Machining Bushings

Choosing the right copper alloy is the first step in producing a high‑performance bushing. Different alloys offer varying strength, machinability, corrosion resistance, and wear properties.

Pure Copper (C110, C101, C102)

Pure copper provides the highest electrical and thermal conductivity. It has good corrosion resistance but low mechanical strength. Machining pure copper is challenging due to its softness, burr formation, and stringy chips. It is used for electrical connectors, bus bars, and heat exchangers rather than heavy‑load bushings.

Brass (C260, C360, C464)

Brass offers excellent machinability (especially C360 free‑cutting brass), moderate strength, and good corrosion resistance. It is ideal for valve components, gears, fittings, and fasteners. However, its electrical conductivity is lower than pure copper.

Bronze (C932, C954, C863)

Bronze is the most common material for industrial bushings. It provides high strength, excellent wear resistance, and good corrosion resistance. Key bronze alloys include:

• C93200 (SAE 660 bronze): Widely used bearing bronze with good machinability and wear resistance.

• C95400 aluminum bronze: High strength and excellent corrosion resistance, especially in marine environments.

• C86300 manganese bronze: Superior strength and impact resistance for heavy‑load machinery.

• Tin bronze alloys: Good sliding performance for pumps, valves, and hydraulic equipment.

Bronze is harder to machine than brass, requiring sharp tools and controlled speeds.

Tellurium Copper (C14500)

Tellurium copper combines high electrical conductivity with improved machinability over pure copper. It is used in electrical contacts, switchgear, and welding applications.

Beryllium Copper (C17200, C17500)

Beryllium copper offers very high strength, fatigue resistance, and good corrosion resistance. It is used in aerospace connectors, non‑sparking tools, and springs. Machining requires proper ventilation due to potentially harmful dust.

C95200 Aluminum Bronze

C95200 (ASTM designation) is a high‑strength aluminum bronze containing 8.5–11.5% aluminum and 2.5–4.5% iron. It provides exceptional corrosion resistance in seawater and chemical environments, high wear resistance, and good machinability. It is ideal for marine bushings, pump components, and heavy machinery.

Material Comparison Table

Tips for Machining Bronze Bushings

Machining bronze and copper alloys requires careful attention to tooling, speeds, feeds, and cooling.

Know the Bronze Type

Bearing bronze (with 6‑8% lead) is often the best choice for bushings because it is durable in high‑friction or high‑wear applications. Other types include silicon bronze, phosphor bronze, aluminum bronze, manganese bronze, and copper‑nickel bronze.

Use Quality Cutting Tools

Using top‑quality cutting tools at the right speed and feed is essential to achieve precision measurements. Carbide or diamond‑coated tools help resist wear and maintain sharp edges. Proper coolant application minimizes heat buildup and prevents material from sticking to the tool.

Address Machining Challenges

• Soft materials (pure copper): Burr formation and dimensional issues; use sharp tools and finishing passes.

• Ductile materials: Long, stringy chips can jam tools; employ chip breakers.

• Hard bronzes: Tool wear is a concern; use coated tools and controlled speeds.

For complex geometries like flanged bushings or oil‑groove designs, CNC turning and milling with precise programming ensure tight tolerances (typically ±0.01 mm to ±0.02 mm for precision components).

CNC Machining Process Flow for Copper Bushings

The manufacturing process of a copper bushing involves several stages:

1. Material Selection – Choose the appropriate copper alloy based on load, speed, environment, and lubrication conditions.

2. Mold Preparation (for cast bushings) – A mold is created with a cavity in the desired shape. Many high‑performance bushings are produced by centrifugal casting, which distributes molten metal evenly along the mold wall, producing dense, defect‑free castings with reduced porosity and improved mechanical properties.

3. Melting and Casting – The copper alloy is melted in a furnace and poured into the mold. Centrifugal casting is especially suitable for cylindrical parts like bushings.

4. Cooling and Solidification – The casting cools and solidifies into a rough blank.

5. Rough Machining – Excess material is removed using CNC lathes and mills to achieve approximate dimensions.

6. Precision Machining – The part is finished to tight tolerances and smooth surfaces (surface finishes can reach Ra 0.2‑0.4 µm). Operations include turning, milling, drilling, threading, and tapping.

7. Heat Treatment (if required) – Annealing or tempering improves hardness and strength.

8. Surface Finishing – Polishing, grinding, or coating enhances appearance, corrosion resistance, and friction properties.

9. Quality Inspection – Dimensional checks, surface finish verification, and mechanical property tests ensure compliance with specifications.

10. Assembly or Packaging – Finished bushings are assembled into products or packaged for shipment.

Recycled copper material from machining chips is often melted for re‑use.

Types of Copper Bushings

Based on design and lubrication method, copper bushings can be classified as:

• Plain cylindrical bushings – Most common, installed in housings to provide a smooth sliding surface for rotating shafts.

• Flanged bushings – Include an integrated flange for axial load absorption; used in pumps, motors, and gear systems.

• Thrust bushings and washers – Support axial loads and prevent excessive friction in rotating machinery.

• Split bushings – Easier to install and remove, ideal for large industrial equipment.

• Self‑lubricating bushings – Contain solid graphite or other lubricants embedded in the copper alloy, reducing the need for external lubrication. Common grades include JDB‑1U, JDB‑1US1, etc.

• Oil‑groove bushings – Feature axial or helical grooves (e.g., 30‑45° angles) to distribute lubricant evenly.

Applications of Copper Bushings

Copper bushings are used across many industries due to their wear resistance, corrosion resistance, and load‑bearing capacity.

• Marine equipment and ship propulsion systems – Propeller hubs, stern tube bearings, rudder bushings (especially C95200 aluminum bronze for seawater resistance).

• Hydraulic cylinders and pump systems – Valve guides, pump bodies, cylinder bushings.

• Industrial gearboxes and heavy machinery – Pivot bushings for excavators, loaders, wear plates.

• Construction and mining equipment – High‑load, low‑speed applications.

• Automotive and transportation systems – Steering systems, transmission components.

• Aerospace – Landing gear components, actuators, structural bushings.

• Chemical and petrochemical – Valve stems, pump parts exposed to corrosive fluids.

• Electrical equipment – Where conductivity and sliding are both required.

Signs of Bushing Failure and How to Fix Them

Understanding failure modes helps in selecting the right bushing and maintenance schedule.

Peeling

Small areas of peeling or flaking caused by hairline cracks, often due to insufficient lubrication or foreign matter infiltration. Remedy: Re‑evaluate lubrication type and methods; enhance sealing to prevent contamination.

Flaking

Caused by improper handling, heavy loads, rust, contamination, or low lubrication. Also due to reduced hardness, improper mounting, or inadequate shaft precision. Remedy: Verify the correct bushing type, re‑evaluate application conditions, design, clearance, and lubrication methods.

Scuffing & Smearing

Rough surface with deposits; often from inadequate lubrication, entrapped foreign particles, or excessive axial loading. Remedy: Re‑evaluate lubricant, lubrication methods, and preload.

Spalling

Result of poor mounting or removal practices, excessive radial load, poor lubrication, or slippage. Remedy: Correct preload, improve operating conditions, and address mounting/removal methods.

Copper Bushings vs. Rolling Bearings

Why Choose EMAR for Custom Copper Bushings?

At EMAR, we specialize in custom copper and bronze bushings produced by centrifugal casting and precision CNC machining. Our components are widely used in marine infrastructure, hydraulic equipment, heavy machinery, and industrial automation worldwide.

We offer:

• Custom dimensions (ID, OD, length) and tight tolerances

• Specific features (flanges, oil grooves, graphite plugs, keyways)

• Wide range of copper alloys: C93200, C95400, C86300, C95200, C17200, and more

• Material certification to ASTM, EN, DIN, or JIS standards

• Engineering support to help you select the right alloy and manufacturing process

Whether you need a standard plain bushing or a custom‑designed flanged sleeve, EMAR delivers precision and durability.

Contact us today:

• Phone: +86 18664342076

• Email: sales8@sjt-ic.com

Let our engineering team review your design and recommend the most suitable copper alloy and machining process for your application.