В области Обработка на станках с ЧПУ and mechanical manufacturing, bronze is an engineering material that cannot be easily replaced. Compared with ordinary углеродистая сталь, stainless steel, or brass, bronze offers unique advantages in wear resistance, anti-galling performance, sliding properties, and long-term service stability. As a result, it is widely used in bearings, bushings, worm gears, pump and valve components, marine fittings, and heavy-duty sliding structures.
This article focuses on machining bronze and provides a systematic analysis from multiple engineering perspectives, including material standards, five-dimensional mechanical properties, machining methods, application scenarios, corrosion mechanisms, and maintenance strategies, helping readers gain a comprehensive understanding of bronze in machining applications.
What Is Bronze? Engineering Definition and Material Nature
Engineering Definition of Bronze
In an engineering context, “bronze” generally refers to copper-based alloys. Common systems include:
- Оловянная бронза: Typical grades include C90500, C90700, and C93200 (SAE 660, commonly known as bearing bronze)
- Алюминий Бронза: Such as C95400 and C95500 (high strength and corrosion resistance, widely used in marine engineering)
- Кремниевая бронза: Such as C65500 (balanced strength, corrosion resistance, and weldability)
- Фосфористая бронза: Such as C51000 and C52100 (good elasticity and wear resistance, often used for thin sheets and spring components, but also machinable)
Influence of Alloying Elements on Performance
Bronze is composed of multiple alloying elements, and different elements give different bronze grades their unique performance advantages.
- Tin (Sn): Improves wear resistance and fatigue resistance
- Aluminum (Al): Significantly enhances strength and corrosion resistance
- Silicon (Si): Improves overall mechanical properties and weldability
- Phosphorus (P): Enhances elasticity and fatigue resistance
- Свинец (Pb): Improves anti-friction properties and machinability
Fundamental Differences Between Bronze and Pure Copper
Compared with pure copper, bronze sacrifices a small amount of electrical and thermal conductivity in exchange for higher strength, lower friction coefficient, and more stable service behavior. This is the fundamental reason bronze is widely used in machining and mechanical applications.
Mechanical Properties of Bronze (Engineering-Level Understanding)
Common Mechanical Property Ranges
| Недвижимость | Typical Range (Common Bronze Values) | Описание |
|---|---|---|
| Density (ρ) | 7.4–8.9 g/cm³ | Most bronzes are slightly lighter than steel or similar |
| Elastic Modulus (E) | 95–125 GPa | Lower than steel (~200 GPa), but sufficiently rigid |
| Tensile Strength (UTS) | 250–750 MPa | Aluminum bronze can be higher; bearing bronze is moderate |
| Yield Strength (YS) | 100–500 MPa | Strongly related to heat treatment and cold working |
| Удлинение | 5%–35% | Bearing bronze and silicon bronze perform well |
| Твердость по Бринеллю (HB) | 60–200+ HB | Aluminum bronze and phosphor bronze are harder |
| Thermal Conductivity (k) | 30–80 W/m·K (typical) | Lower than pure copper but still good |
| Friction / Anti-galling | Превосходно | A key reason bronze is used for bushings |
High elongation helps resist impact and prevent brittle fracture, while moderate hardness achieves a balance between wear resistance and machinability.
Why Bronze Does Not Pursue “Extreme Strength”
The engineering value of bronze lies not in replacing high-strength steel, but in delivering a balanced combination of stable load-bearing capability, low friction, and long service life.
International Standard Grades of Bronze (ASTM / UNS / SAE)
Different bronze alloys vary greatly in machinability, strength, corrosion resistance, and cost. Therefore, when discussing machining bronze, it is essential to clearly specify alloy grades and systems.
| Bronze Type | International Standard Grade | Applicable Standard |
|---|---|---|
| Leaded Tin Bronze (Bearing Bronze) | C93200 / SAE 660 | ASTM B505 |
| Оловянная бронза | C90700 / C90500 | ASTM B505 |
| Алюминий Бронза | C95400 / C95500 | ASTM B148 |
| Кремниевая бронза | C65500 | ASTM B30 |
| Фосфористая бронза | C51000 / C52100 | ASTM B139 |
UNS numbers uniquely identify materials, while ASTM standards define chemical composition and mechanical properties.
5 Dimensional Mechanical Property Comparison of Different Bronze Materials
The following comparison is based on tensile strength, yield strength, hardness, elongation, and machinability.
| UNS Grade | Растяжение МПа | Yield MPa | Hardness HB | Elongation % | Обрабатываемость |
|---|---|---|---|---|---|
| C93200 | 240–310 | 125–170 | 65–90 | 10–20 | Высокий |
| C90700 | 275–345 | 150–200 | 70–100 | 15–30 | Относительно высокий |
| C90500 | 260–310 | 140–180 | 65–95 | 20–35 | Относительно высокий |
| C95400 | 620–760 | 275–450 | 140–190 | 10-18 | Средний |
| C95500 | 655–790 | 380–550 | 170-220 | 8–15 | Низкий |
| C65500 | 380–550 | 170–310 | 100–150 | 20–35 | Относительно высокий |
| C51000 | 350–500 | 250–420 | 100–150 | 5–20 | Средний |
| C52100 | 440–620 | 350–550 | 130–180 | 5–15 | Низкий |
Root Causes of Performance Differences
Performance differences mainly result from alloy composition ratios, grain structure, and casting or processing conditions.
Advantages and Disadvantages of Bronze Materials
Преимущества
- Wear resistance and anti-galling performance
- Strong corrosion resistance (especially silicon and aluminum bronze in marine environments)
- Vibration damping and low noise
- Good thermal and electrical conductivity compared with steel
- Excellent castability and machinability
Недостатки
- Higher material cost than carbon steel
- Strength limit depends on alloy system
- Some bronzes contain lead and are unsuitable for food or drinking water applications
- Susceptible to tool adhesion or built-up edge if cutting parameters are improper
Bronze is usually selected for system longevity and stability rather than lowest material cost.
Available Machining Processes for Bronze
Bronze is a highly machinable engineering copper alloy, but different alloy systems show significant differences in cutting performance. Therefore, machining processes should be selected based on part geometry, precision requirements, and service conditions.
Токарная обработка с ЧПУ
Токарная обработка с ЧПУ is the most common bronze machining process, mainly used for rotational parts such as bushings, sleeves, and wear rings. Stable dimensions can be achieved during turning.
Avoid excessively low feed rates to prevent rubbing and surface smearing. For high-strength aluminum bronze, cutting speeds should be reduced to control tool wear.
Фрезерование с ЧПУ
Фрезерование с ЧПУ is suitable for complex or non-rotational bronze parts such as valve bodies, flanges, sliders, and mounting bases. It is widely used in export-oriented CNC machining.
Due to continuous chips, attention should be paid to chip evacuation and tool geometry to reduce adhesion and surface defects.
Drilling, Boring, and Reaming
Hole machining is common in bronze components, especially for bearing and assembly holes. Simple holes can be drilled directly, while high-precision holes require combined drilling, boring, or reaming.
Chip breaking and heat dissipation are critical to avoid dimensional instability or surface damage.
Tapping and Threading
Bronze is generally suitable for threading and is commonly used in valve bodies and connectors. Tin bronze and bearing bronze tap reliably.
For high-strength aluminum bronze, cutting oil or thread milling is recommended to reduce the risk of tap breakage or thread tearing.
Grinding, Honing, and Finishing
For bronze parts requiring high surface finish or tight tolerances, шлифование or honing may be applied, such as for precision bearing bores.
Because bronze is relatively soft, processing pressure and parameters must be carefully controlled to avoid surface smearing or localized overheating.
Casting + Secondary Machining
Casting combined with CNC secondary machining is the most common and cost-effective manufacturing route for bronze parts. Casting provides near-net shapes, while machining ensures critical dimensions.
This approach is ideal for medium to large, complex, or batch-produced bronze components such as bearings, valve bodies, and pump housings.
Surface Treatment and Post-Processing
After machining, bronze parts typically require only deburring, chamfering, or simple polishing. Some appearance or storage parts may receive protective oil or sandblasting.
Bronze generally does not rely on surface coatings for performance improvement, and improper chemical treatments may increase corrosion risk.
Application Fields and Common Components
Mechanical Transmission and Wear Parts
- Bushings, bearings, sliders, wear washers
- Bronze worm gears paired with steel worms to reduce noise and wear
Pump and Valve Systems
- Valve bodies, valve seats, spools, pump wear rings, sealing seats
- Aluminum bronze or silicon bronze is preferred in seawater or saline environments
Marine and Offshore Hardware
- Propeller components, shaft bushings, seawater-resistant fasteners, deck fittings
- Typical alloy: aluminum bronze
Electrical and Explosion-Proof Applications
- Certain applications utilize the low-sparking characteristics of copper alloys, subject to relevant standards
Best Bronze Materials for Machining
For easy turning and milling, high cost-effectiveness, and stable production:
- C93200 / SAE 660 (Bearing Bronze)
Excellent machinability, wear resistance, and anti-galling performance. Suitable for bushings, bearings, and wear components.
For high strength and seawater resistance:
- C95400 (Aluminum Bronze)
Stronger and more corrosion-resistant, suitable for marine, heavy-duty, and critical pump/valve components, but with higher tool wear.
For corrosion resistance and weldability:
- C65500 (Silicon Bronze)
Good appearance, corrosion resistance, and weldability, suitable for coastal hardware and corrosion-resistant fasteners.
Machinability Comparison Between Bronze and Brass
In most cases, bronze is harder to machine than brass.
Many brasses, especially leaded brasses, offer excellent chip breaking and low cutting resistance, resulting in smooth machining.
Bronze is generally tougher and more wear-resistant, which can lead to continuous chips, surface smearing, and higher tool wear, particularly with aluminum bronze.
Bearing bronze (C93200), however, is not particularly difficult to machine—just less forgiving than free-machining brass.
How to Clean Bronze Parts? Can WD-40 Be Used?
Recommended Cleaning Methods
Light dust or fingerprints:
Warm water, mild detergent, and a soft cloth. Dry thoroughly after rinsing.
Oil or cutting fluid residue:
Neutral degreaser or isopropyl alcohol (IPA). Ensure complete drying after cleaning.
Light oxidation or darkening:
Mild copper/bronze cleaners, or diluted lemon juice or vinegar followed by immediate rinsing and drying. Acidic cleaning should be short-term only.
Can WD-40 Be Used?
Yes, but only in appropriate situations.
Suitable uses of WD-40:
- Moisture displacement
- Light oil removal
- Temporary rust or corrosion protection
Not recommended for:
- Surfaces requiring painting, bonding, or adhesive application
- Long-term lubrication of precision sliding components
A safer approach is: cleaning → drying → applying a suitable protective oil or wax based on service conditions.
Substances That Can Corrode Bronze
Bronze is generally corrosion-resistant but not immune.
High-Risk Environments
- Ammonia-containing environments (NH₃), which may cause stress corrosion
- Strong acids or oxidizing acids such as nitric acid
- Sulfide-containing environments (H₂S), causing black sulfide films
- Chloride-rich environments (seawater, salt spray), leading to pitting or crevice corrosion
- Galvanic corrosion when in contact with dissimilar metals in electrolytes
Practical Prevention Tips
- Avoid prolonged exposure to strong acids or alkalis
- Prefer aluminum or silicon bronze for coastal environments
- Use insulation, sealants, or coatings to isolate dissimilar metals
Is Bronze a Valuable Scrap Metal?
Generally, bronze is considered a relatively valuable scrap metal.
As a copper-based alloy, bronze has high recycling value and is categorized as a high-value non-ferrous metal.
However, scrap value depends on alloy type, purity, contamination with steel chips or coatings, and local market conditions.
It is recommended to separate bronze chips by alloy type during machining, as price differences can be significant.
Can Bronze Be as Sharp as Steel?
Bronze can be sharpened to a very sharp edge, but it cannot maintain sharpness as long as steel.
Hardened tool steels achieve higher hardness and wear resistance through heat treatment, resulting in better edge retention.
Most bronzes lack the hardness required for long-lasting cutting edges and tend to dull or roll more easily.
Therefore, bronze can be sharpened temporarily but is not ideal for cutting tool applications.
Заключение
Machining bronze is not simply about choosing a copper alloy, but about balancing mechanical performance, machinability, wear resistance, and long-term service reliability. By understanding international bronze grades, key mechanical properties, suitable machining processes, corrosion risks, and proper maintenance methods, engineers and buyers can make more informed material and manufacturing decisions.
Whether used for bearings, bushings, worm gears, pump and valve components, or marine applications, bronze remains a proven engineering material that delivers stable performance across a wide range of operating conditions. Proper material selection and machining strategy are essential to fully realize the advantages of bronze in CNC machining applications.if you want to know more details or get price of machining bronze,you can feel free to связаться с нами.
