Bimetal Sliding Blocks: Applications & Material Selection Guide for High-Load, Low-Speed Machinery

What Is a Bimetal Sliding Block?

A bimetal sliding block (also called steel-backed bronze bearing plate) is a composite bearing solution engineered for high temperature, heavy load, and low-speed operating conditions.

Typical structure:

• Steel backing layer → structural rigidity and shock resistance

• Bronze alloy layer → load-bearing surface

• Embedded solid lubricants (graphite / PTFE) → self-lubricating network

Unlike conventional plain bearings that rely entirely on oil film formation, bimetal sliding blocks operate using a thermo-activated solid lubrication mechanism. Friction heat triggers micro-transfer of solid lubricant onto the contact surface, forming a mixed lubrication layer (solid film + oil residue), which:

• Prevents metal-to-metal seizure

• Reduces friction under boundary conditions

• Maintains lubrication even during start-stop cycles

This makes them ideal for environments where hydrodynamic lubrication cannot be reliably established.

---

Key Advantages in Industrial Applications

1. Superior Load Capacity

The steel backing significantly increases compressive strength compared with monolithic bronze bushings.

Typical allowable surface pressure:

• 100–250 MPa (depending on alloy and design)

---

2. Reliable Performance in High Temperature

Bronze + graphite systems remain stable in 200–400°C environments (material dependent).
Solid lubricant prevents adhesive wear when oil degrades.

---

3. Maintenance Reduction

• Operates with minimal lubrication

• Suitable for oil-free or contaminated environments

• Lower downtime in remote installations

---

Major Industrial Applications

1. Continuous Casting Equipment

Continuous casting machines operate under extreme heat and heavy cyclic loads.

Typical positions:

• Oscillation frames

• Guide segments

• Roller support blocks

Why bimetal sliding blocks?

• High load + low speed

• High temperature exposure

• Limited lubrication access

---

2. Steel Rolling Mills

Steel rolling systems generate heavy shock loads and scale contamination.

Applications:

• Guide plates

• Sliding supports

• Hydraulic cylinder mounts

Solid lubricant prevents seizure under boundary lubrication conditions.

---

3. Mining Machinery

Mining machinery operates in dusty, abrasive environments.

Advantages:

• Oil contamination resistance

• Long service intervals

• Reliable startup under heavy load

---

4. Rail Systems & Heavy Transport

Rail transport suspension and support brackets demand:

• Impact resistance

• Vibration tolerance

• Low maintenance

Bimetal sliding blocks offer durable, self-lubricating performance during repeated start-stop cycles.

---

5. Marine & Turbine Applications

Marine engineering
Gas turbine

Used in auxiliary support mechanisms exposed to:

• Corrosive atmospheres

• High thermal stress

• Lubrication instability during startup

---

Material Selection Guide for Bimetal Sliding Blocks

Selecting the correct bronze alloy and lubricant system is critical for performance optimization.

Step 1: Define Operating Parameters

Key engineering inputs:

• Surface pressure (MPa)

• Sliding speed (m/s)

• PV value (MPa·m/s)

• Operating temperature (°C)

• Start-stop frequency

• Environmental contamination level

---

Step 2: Choose Bronze Alloy System

1. CuPb10Sn10 (Lead Bronze)

Best for:

• Heavy load

• Moderate speed

• Shock conditions

Characteristics:

• Excellent embedability

• Good anti-seizure behavior

• Suitable for boundary lubrication

---

2. CuSn6 / CuSn8 (Tin Bronze)

Best for:

• Higher temperature

• Corrosion resistance

• Medium-to-high load

Advantages:

• Higher strength

• Better wear resistance than lead bronze

• Compatible with graphite plugs

---

3. Graphite-Embedded Bronze

Best for:

• Dry running

• Low-speed heavy load

• Limited lubrication access

Graphite forms a solid lubricating film under friction heat activation.

---

Step 3: Evaluate PV Value

The PV value determines thermal stability.

Typical safe range:

• 1.5–3.5 MPa·m/s (dry)

• Higher with auxiliary lubrication

If PV exceeds design limit:

• Increase contact area

• Upgrade alloy strength

• Improve heat dissipation

---

Step 4: Temperature Compatibility

---

When NOT to Use Bimetal Sliding Blocks

Avoid in:

• High-speed hydrodynamic applications

• Ultra-precision positioning systems

• Extremely low-load, high-speed rotation

In such cases, rolling bearings or PTFE-lined composite bearings may perform better.

---

Engineering Insight: Why They Excel in Low-Speed Heavy Load Conditions

At low speed, oil film thickness approaches zero.
Traditional fluid lubrication fails.

Bimetal sliding blocks solve this by:

• Using steel backing for structural strength

• Employing bronze for conformability

• Activating solid lubricant via friction heat

This creates a self-renewing boundary film, reducing adhesive wear and preventing galling.

---

Conclusion

Bimetal sliding blocks are a proven solution for:

• High temperature

• Heavy load

• Low speed

• Contaminated or oil-limited environments

Proper material selection—especially bronze alloy type and solid lubricant configuration—is essential for maximizing lifespan and reliability.

For optimal performance, always evaluate:

• Load

• Speed

• PV value

• Temperature

• Maintenance constraints

When selected correctly, bimetal sliding blocks provide a long-term, low-maintenance alternative to conventional bronze bushings in harsh industrial applications.