What Is Bronze Made Of — Bronze Bushings, Sleeves, Plates & Precision CNC Parts

An engineering reference for bronze composition, bronze bearing families, and finished precision bronze components for machinery.

What Is Bronze Made Of?

Bronze is a family of copper-based alloys in which the primary alloying element is neither zinc (which defines brass) nor nickel (which defines cupronickel). The classic bronze is an alloy of copper (Cu) and tin (Sn); tin raises hardness, strength, and wear resistance and lowers the melting point. Modern engineering bronzes add phosphorus, lead, aluminum, nickel, manganese, or silicon to obtain targeted properties for bearings, marine service, springs, and precision parts.

• Density: tin bronzes are near 8.8–8.9 g/cm³; aluminum bronzes are lighter at roughly 7.5–7.8 g/cm³.
• Melting range: approximately 930–1080 °C depending on alloy.
• Thermal conductivity: about 35–70 W/(m·K).
• Electrical conductivity: roughly 10–15% IACS (well below pure copper).
• Corrosion behavior: a self-healing basic-carbonate patina forms on the surface and slows further attack.

Bronze Alloy Families & Cross-Standard Grade Map

“Bronze” is a family name only. For procurement, an exact grade must be specified. The table below shows typical cross-standard correspondences; values differ by standard edition and material condition, so the current edition must be confirmed.

Bronze Bearings

Bearings are a major engineering use of bronze. By lubrication mechanism they divide into oil-/lead-containing anti-friction bearings, sintered oil-impregnated (self-supplying) bearings, and solid-embedded self-lubricating (oilless) bearings; by service they divide into general-purpose, heavy-duty, and marine grades.

Bearing Bronze — C93200 / SAE 660

Oil-Impregnated Sintered Bronze — SAE 841

Solid-Embedded Self-Lubricating Bronze — JDB / JFB / JSP (Oilless)

Standard: GB/T 23894-2009 (copper-alloy solid-embedded self-lubricating bearings). Forms: JDB straight sleeve, JFB flange, JDW split, JSP sliding plate, JTW thrust washer. Graphite plugs (fixed carbon ≥98%, coverage 20–30%) form a transfer film for oil-free, high-temperature, contamination-tolerant, low-noise running. Note: matrices are typically cast aluminum bronze — specify “cast aluminum bronze (JDB type)” and do not confuse with wrought QAl9-4 rod.

Marine-Grade Bearing Materials — C95400 / C95500 / C95800 / CuSn12

* CuSn12 strength varies widely by casting method (sand ≈250, centrifugal/continuous ≈400 MPa). Standards: ASTM B148 (sand) / B271 (centrifugal) / B505 (continuous); EN 1982; DIN/ISO.

Bronze Sleeves (Plain Bearings)

A bronze sleeve (bushing) is a tubular plain bearing fitted over a shaft, usually made from a continuous-cast bronze tube blank, then CNC-turned inside/outside, grooved, oil-holed, and chamfered. The aim is ID/OD fit accuracy and friction-surface quality.

• Bore (ID): F7 (interference/transition; approaches actual size after press-fit).
• Outer diameter (OD): m6 (with H7 housing bore, slight interference or transition).
• Stock tolerance: ID ±.001 in; OD +.002~+.003 in; length ±.005 in.
• Optional forms: straight / flanged / thrust washer; axial or circumferential oil grooves, holes, pockets; split, spherical, custom; graphite-embedded (oilless) or sintered oil-impregnated.

Bronze Plate

“Bronze plate” usually means wrought phosphor bronze plate/strip (ASTM B103) for springs, contacts, bearing backs, and precision stamping; aluminum bronze is also supplied as plate/forging stock (ASTM B148 / B150). Cast bronzes such as C93200 are normally supplied as solid rod or tube blank rather than plate.

Wrought Phosphor Bronze Plate (ASTM B103 / B139 / B159)

Aluminum Bronze Plate / Forging Stock (ASTM B148 / B150)

Bronze Finished Precision Parts

These are bronze components brought to net, assemblable dimensions by casting/forging/powder metallurgy plus precision machining — bearings, bushings, worm gears, valve stems, pump impellers, thrust washers, eccentric bushings, rolling-mill nuts, sliding plates, and contact terminals.

• Dimensional tolerance: precision CNC can reach ±0.01 mm (turning ±0.001 in).
• Surface finish: Ra 0.2–0.8 µm (finish machining).
• Geometry: roundness / flatness checked by CMM.
• Deburring: chamfer / edge-break for safe assembly.

Bronze CNC Parts

Bronze is machined by turning, milling, drilling, tapping, and grinding. Alloy behavior differs sharply: leaded bronzes are notably free-machining, aluminum bronzes are abrasive and prone to work-hardening, and manganese bronzes are tough and tend to string chips. Core strategy: sharp edge + positive rake + strong chip evacuation + temperature control.

Material Selection Guidance

Compliance & Engineering Cautions

About the Supplier

VIIPLUS SOLUTIONS ® supplies certified bronze alloys, custom dimensions, and technical support, with production and logistics coordinated to meet agreed delivery schedules. Share your operating conditions — load, speed, environment, and lubrication access — and the alloy and geometry can be refined to the application.

The Engineer’s Guide to Bronze Bushings: Technical FAQ & Material Selection

Deep-dive FAQ on bronze bushing selection. Compare Cast vs. Sintered properties, analyze C95400 vs. C93200 alloys, and understand custom machining tolerances for heavy-duty industries.

1. Material Science & Engineering Logic: Why Bronze?

Engineers specify bronze not just because it is “strong,” but because of its specific tribological properties relative to steel shafts.

Q: Why is bronze the dominant material for heavy-duty bushings?

A: Bronze functions as a sacrificial wear material. In any tribological system (friction pair), one component must wear to preserve the other.

• The Logic: It is cheaper and easier to replace a bronze bushing than a precision-ground steel shaft or hydraulic cylinder rod.

• Key Engineering Properties:

  • Anti-Galling: Unlike steel-on-steel, bronze resists “cold welding” (seizing) under high contact pressure.

  • Thermal Conductivity: It effectively draws heat away from the friction zone, preventing oil film breakdown.

  • Embeddability: Softer bronze alloys (like Tin Bronze) allow abrasive particles to embed into the wall, preventing them from scoring the shaft.

Q: Alloy Selection Matrix: Which Bronze should I choose?

Selecting the wrong alloy is the #1 cause of premature failure. Use this contrast table to decide:

2. Manufacturing Methodology: Cast vs. Sintered

Understanding the difference between “Cast” and “Sintered” is critical for determining load capacity and lubrication strategy.

Q: What is the functional difference between Cast Bronze and Sintered Bronze Bar Stock?

The Contrast Logic:

A (Deep Dive):

• Cast Bronze (VIIPLUS Standard): Produced via continuous casting, ensuring a fine grain structure free of blowholes. This is mandatory for structural parts in mining and construction.

• Sintered Bronze: Best when maintenance is impossible. As the bearing warms up, oil expands from the pores to lubricate the shaft; as it cools, capillary action draws the oil back in.

3. Customization & Machining: Solving the “Fit” Problem

Q: Why specify Custom Machining over Standard “Off-the-Shelf” sizes?

A: Standard sizes often result in compromised engineering. Custom machining addresses three critical pain points:

1. Tolerance Optimization: Standard bushings typically have “loose” tolerances. Custom machining allows for interference fits (Press Fit) tailored to the housing expansion rates, typically holding +/- 0.001 inches or tighter depending on diameter.

2. Lubrication Management: A standard plain bush may starve the center of the shaft. Customization allows for specific groove patterns:

   • Figure-8 Grooves: For oscillating motion (pins).

   • Double Loop: For continuous rotation.

   • Solid Lubricant Inserts: Drilling specifically for Graphite Plugs (Oilless) for submerged use.

3. Geometry: Integration of thrust flanges, locating notches, or non-circular IDs to prevent rotation.

Q: What data is required for a precise RFQ?

To avoid production delays, engineers should provide:

• The Mating Part Hardness: Essential to ensure the bushing doesn’t wear the shaft.

• The “PV” Value: Pressure x Velocity calculations to determine wall thickness.

• Environmental Context: Saltwater? Acidic slurry? High heat? (Determines Alloy).

• Technical Drawing: PDF or CAD with Geometric Dimensioning and Tolerancing (GD&T).

4. Industry-Specific Applications & Case Studies

Q: How do environmental factors dictate Bronze usage?

A. Marine & Offshore (Saltwater Corrosion)

• Problem: Standard copper alloys turn green and degrade (verdigris).

• Solution: Aluminum Bronze (C95400/C95500). The aluminum content forms a passive oxide layer that heals itself, making it impervious to chloride attack. Used in rudder pintles and winch bearings.

B. Hydraulics & Heavy Earthmoving (Impact Loading)

• Problem: Excavator bucket pins experience massive “Shock Loads” that crack brittle materials.

• Solution: Cast Manganese Bronze (C86300) or High-Tensile Cast Bronze. These handle bearing pressures exceeding 4,000 psi.

• Design Note: Often paired with “Grease Grooves” to ensure lubricant stays in the load zone during static periods.

C. Oil & Gas (High Pressure / Valve Components)

• Problem: Valve seats must endure high pressure without deforming.

• Solution: Precision-machined bronze with high compressive yield strength ensures the valve seals tightly even after thousands of cycles.

5. Quality Assurance & Logistics (VIIPLUS Standards)

Q: How do I verify the material composition?

A: In high-stakes industries, “trust” is not enough. You should demand:

• Mill Test Reports (MTRs): Verifies the chemical composition (Copper/Tin/Lead/Zinc % coverage).

• Dimensional Inspection Reports: Verification of ID/OD/Concentricity before shipment.

• VIIPLUS Assurance: We guarantee casting to spec. If a custom bronze bushing is not machined 100% to the drawing, it is replaced.

Q: Shipping & Lead Times for Custom Parts?

A: While standard parts are immediate, custom manufacturing involves casting and CNC machining.

• Prototyping: Available for validation testing before mass production.

• Logistics: We ship extensively across the globle, utilizing optimized shipping networks for heavy freight (bronze is dense) to minimize landed costs.

Managing custom part procurement can often mean dealing with unpredictable lead times and inconsistent quality—issues that pull your attention away from core engineering priorities.

At Pre-part, we turn that experience into a steady, reliable, and mutually beneficial partnership. We specialize in precision CNC machining and the production of bearings, bushings, plates, and washers for prototypes and small-batch manufacturing. Our focus is unwavering: consistent quality and on-time delivery.

We provide detailed, non-binding proposals that include potential design improvements to enhance manufacturability. This gives you clear options and practical insights before any commitment, helping you mitigate risks tied to performance, budget, and schedule.

If you’re looking for a manufacturing partner committed to clarity and strong engineering support, I’d be thrilled to review your requirements and prepare a formal quotation whenever you’re ready.

What Is Bronze Made Of — Composition, Bronze Bushings, Sleeves, Plates & Precision CNC Parts

A practical, engineering-focused guide to bronze alloys and their finished components for machinery.

What Is Bronze Made Of?

Bronze is a family of copper-based alloys in which the primary alloying element is not zinc (an alloy with zinc as the main additive is brass). The classic bronze is an alloy of copper (Cu) and tin (Sn). Modern engineering bronzes extend this definition by using phosphorus, lead, aluminum, nickel, manganese, or silicon as significant alloying elements to obtain specific mechanical and corrosion properties.

For tin bronzes, the nominal composition typically falls in the range of about 88–95% copper with 5–12% tin. This ratio does not apply to all bronzes: aluminum bronzes, silicon bronzes, and manganese bronzes use different primary additives and follow entirely different composition ranges. Representative compositions include:

• Tin bronze (e.g., C93200 / SAE 660): roughly 83% Cu, 7% Sn, 7% Pb, 3% Zn (lead present as discrete particles).
• Aluminum bronze (e.g., C95400): copper remainder (~81–86%), 10.5–11.5% Al, 3.0–5.0% Fe, Ni ≤1.5%.
• Nickel-aluminum bronze (e.g., C95500): copper remainder, ~10–11.5% Al, 3–5% Fe, 4–5.5% Ni.

Is Bronze a Metal?

Yes. Bronze is an alloy — a mixture in which the base metal is copper, a true metal, alloyed with tin and/or other elements. The resulting material exhibits metallic properties such as electrical and thermal conductivity, malleability, and metallic luster, so bronze is classified as a metal.

Bronze Bushing & Plain Bearing Families

A plain bearing (or bushing) is a sleeve or tube with no moving parts; the shaft rotates against its inner surface. Bronze is widely used for plain bearings because of its strength, wear resistance, and ability to operate under boundary-lubrication conditions. The main bronze bushing types are outlined below.

1. Bearing Bronze (SAE 660 / C93200)

This leaded tin bronze contains discrete lead particles that improve machinability, provide embeddability for small abrasive contaminants, and support boundary lubrication. It is commonly used for general-purpose bushings, sleeves, and thrust washers. Continuous-cast stock is covered by ASTM B505; static and centrifugal cast forms are covered by ASTM B271. Allowable PV values are lubrication- and application-dependent and are frequently cited in the range of roughly 50,000–75,000 (psi·ft/min) under adequate lubrication.

2. Aluminum Bronze (C95400 / C95500)

Aluminum bronze offers high strength and high corrosion resistance, and is suited to heavy-duty, marine, and mining service where resistance to seawater and abrasive conditions is required. C95400 and C95500 (nickel-aluminum bronze) are covered by ASTM B148. These grades are lead-free, which is relevant where material restrictions on lead apply.

3. Oil-Impregnated Bronze (SAE 841)

Made by powder metallurgy from a copper–tin mix (commonly near CuSn10) with a porous structure that is vacuum-impregnated with oil. The retained oil provides self-lubrication, making this grade suitable for reduced-maintenance or difficult-to-service locations and higher-speed applications. Covered by ASTM B438 (with the equivalent GB/T 5143 for sintered bearings). Load and speed limits are governed by oil retention and pore structure.

4. Phosphor & Tin Bronze

Phosphorus is added to tin bronze as a deoxidizer and to increase hardness and wear resistance. These alloys show low friction and good toughness, and are used in oscillating or shock-loaded machinery. Wrought strip and plate grades include C51000, C52100, and C52400 (ASTM B103); cast grades serve bushing and wear-plate duties.

5. Flanged Bronze Bushings

An integrated flange allows the bushing to carry combined radial and axial (thrust) loads and simplifies mounting and alignment. These are used in automotive, construction, and marine assemblies where axial location matters.

6. Cast Bronze Bushings

Produced by sand, static, or centrifugal casting, cast bronze bushings are dense and non-porous (contrast with sintered grades) and provide high strength, impact resistance, and heat resistance. They are applied in hydraulics, construction equipment, and repair or replacement parts.

7. Graphite-Embedded (Oilless) Bronze Bushings — JDB / JFB / JSP

A solid bronze body is fitted with embedded graphite plugs that act as a dry lubricant. These bushings run without added oil across a broad temperature range (commonly about −40 °C to +400 °C) and suit conditions where oil access is limited or contamination from grease is undesirable. Relevant Chinese standard: GB/T 23894-2009.

Bronze Sleeve (Plain Bearing) and Bearing Liner

A bronze sleeve bearing is a plain bearing in tubular form. A bearing liner is a different construction: a strong backing (often steel) carries the structure, with a thin bronze layer bonded to the running surface. This bimetal design combines backing rigidity with a bronze wear surface. Typical fits for a bronze sleeve are an inner bore near F7, outer diameter near m6, and a housing bore near H7; oil grooves or holes may be added where lubrication is supplied.

Bronze Plate

Plate products are usually wrought alloys:

• Phosphor bronze plate — C51000, C52100, C52400 (ASTM B103): springs, electrical contacts, and bearing backs.
• Aluminum bronze plate — C95400, C95500, C95800 (ASTM B148 / ASTM B150): wear plates and structural parts.

Cast bronzes such as C93200 are normally supplied as tube or bar stock for machining rather than as rolled plate.

Bronze Finished Precision Parts & CNC Machining

Finished precision bronze parts can be held to tight tolerances (commonly around ±0.01 mm) with surface finishes in the Ra 0.2–0.8 µm range, and are typically verified by coordinate measuring machine (CMM).

For CNC machining, alloy choice strongly affects tooling behavior:

• Leaded bronzes machine most freely and are gentle on tools.
• Aluminum bronzes are more abrasive to cutting tools and require attention to edge wear.
• Manganese bronzes are among the more difficult to machine because of higher strength and toughness.

A practical machining approach uses sharp inserts, positive rake angles, strong chip evacuation, and temperature control to limit work hardening and burr formation.

Matching Alloy to Application

The guidance below is for preliminary material selection; final choice should be confirmed against the operating load, speed, temperature, lubrication access, and the applicable standard and material certificate.

• General load-bearing SAE 660 (C93200)
• High load / corrosive / marine Aluminum Bronze (C95400 / C95500)
• Reduced-maintenance / inaccessible Oil-Impregnated (SAE 841) or Graphite-Embedded (JDB)
• Oscillating / shock-loaded Phosphor & Tin Bronze
• Thrust + radial / easy mount Flanged Bronze Bushing
• High impact / durability Cast Bronze Bushing

Quick Reference Table

About the Supplier

VIIPLUS SOLUTIONS ® supplies certified bronze alloys, custom dimensions, and technical support, with production and logistics coordinated to meet agreed delivery schedules. Share your operating conditions — load, speed, environment, and lubrication access — and the alloy and geometry can be refined to the application.