Pump Bearing Materials: Metal & Non-Metal Selection

Pump bearing materials are usually split into metal and non-metal families. For water, sewage, chemical, and high-temperature pumps, the best choice depends on load, speed, temperature, lubrication, corrosion, and particle contamination. Common metal choices include Babbitt, tin-based bearing alloys, lead-based alloys, and copper alloys; common non-metal choices include PTFE, graphite, rubber, cemented carbide, and silicon carbide.

Because many pump failures start at the interface between shaft, bearing, and seal, material selection should be treated as a system problem. Pair the correct plain pump bearings with compatible shaft bushings and pump shaft seals to avoid galling, dry running, and premature wear.

Pump Bearing Materials: Metal Options

Metal sliding bearings are preferred when the pump needs high load capacity, good thermal conductivity, and predictable behavior under oil or grease lubrication. They are also easier to machine, inspect, and reline in many industrial pump services.

Bearing Alloy, Babbitt, and White Metal

Bearing alloys, often called Babbitt or white metal, are traditionally used for journal and sliding bearings. Their main alloying elements include tin, lead, antimony, and copper, with antimony and copper added to improve strength and hardness.

Two practical variants dominate:

• Tin-based Babbitt: grades such as ZSnSb11Cu6 and ZSnSb8Cu4 are generally stronger, harder, and more corrosion-resistant than lead-based grades, so they are preferred for demanding pump services.
• Lead-based Babbitt: grades such as ZPbSb16Sn16Cu2 have lower strength, hardness, and corrosion resistance, but lower cost. They can still be suitable when operating conditions are moderate and budget is a key constraint.

Because Babbitt alloys have relatively low melting points, they are typically suited to services below about 150°C. If the pump runs hotter, consider bronze, graphite, PTFE composites, or silicon carbide instead.

Copper-Based Alloys

Copper-based materials offer better heat transfer than steel and good wear resistance when properly lubricated. They are often machined to a fine surface finish so the bearing bore contacts the shaft smoothly.

Common copper families include brass, bronze, and leaded bronze. Tin bronze with phosphorus is often used for medium-speed, heavy-load, or impact-loaded bearings, while tin-zinc-lead bronze can be suitable for medium-speed, medium-load pump duty.

Copper alloys tolerate higher operating temperatures than Babbitt, but they have lower conformability, embeddability, and friction compatibility. For clean, well-lubricated pumps, bronze is a robust workhorse; for contaminated or marginal-lubrication pumps, softer Babbitt may protect the shaft better.

Pump Bearing Materials: Non-Metal Options

Non-metal pump bearings are selected when the application needs self-lubrication, chemical resistance, dry running tolerance, or higher temperature capability than metals can provide. They also reduce dependence on oil film, which can be valuable in submersible pumps, wastewater pumps, and process pumps.

PTFE and Filled Polymers

PTFE provides low friction, good thermal stability, and chemical resistance. It does not absorb water, is non-sticky, and is non-flammable, and it can operate across a very wide temperature range, commonly cited from about -180°C to 250°C.

Its weaknesses are high thermal expansion, lower dimensional stability, and poor thermal conductivity. For pump bearings, PTFE is often reinforced with metal particles, fibers, graphite, or inorganic fillers to improve load capacity and heat dissipation.

Graphite Bearings

Graphite is a classic self-lubricating bearing material. It machines easily, becomes smoother as it wears, and can operate with little or no external lubricant. That makes it useful for high-temperature, chemically aggressive, or dry-running pump positions.

The main drawback is poor mechanical strength and impact resistance, so graphite is generally better for light-load applications. To improve performance, graphite is often impregnated with Babbitt, copper alloy, or antimony alloy.

• Babbitt-impregnated graphite: commonly used around 120–180°C.
• Copper-impregnated graphite: can tolerate temperatures up to about 300°C.
• Antimony-impregnated graphite: may be used up to about 500°C in suitable services.

Rubber Bearings

Rubber provides elasticity, vibration damping, and good resilience in water-lubricated environments. It can absorb shocks and tolerate some misalignment better than rigid materials.

However, rubber has poor thermal conductivity, can be difficult to machine, and is usually limited to about 65°C. It also needs continuous water lubrication and cooling, which is why it is selected less often unless the pump design specifically supports water-lubricated operation.

Cemented Carbide Bearings

Cemented carbide, also called hard alloy, offers high hardness, wear resistance, strength, toughness, heat resistance, and corrosion resistance. Bearings made from cemented carbide can run smoothly, hold tight tolerances, and last a long time in abrasive or high-load conditions.

The trade-off is cost. Cemented carbide is typically reserved for severe services where frequent replacement of softer materials would cause downtime.

Silicon Carbide Bearings

Silicon carbide is an engineered ceramic with hardness second only to diamond among common bearing materials. It provides excellent chemical resistance, wear resistance, high-temperature strength, low friction, high thermal conductivity, and low thermal expansion.

Pressureless sintered SiC and hot-pressed SiC are especially valued as sliding bearing and mechanical seal face materials in oil, metallurgy, chemical processing, aerospace, and nuclear-related equipment. For dirty, corrosive, or high-speed pump environments, silicon carbide often outperforms metals and polymers.

See a technical overview of plain bearing principles for background on lubrication regimes and bearing surface behavior.

How to Choose Pump Bearing Materials by Service Condition

Use the operating condition, not the material name alone, to select the bearing. The following practical rules help avoid common pump bearing failures.

• Clean water, moderate temperature: tin-based Babbitt, bronze, or reinforced polymer may work. If the pump is lubricated properly, metal bearings give predictable load capacity.
• High-temperature pump service: avoid standard Babbitt above about 150°C. Consider bronze, graphite, PTFE composites, cemented carbide, or SiC depending on load and corrosion.
• Chemical or wastewater pumps: prioritize corrosion resistance and embeddability. PTFE, graphite, and SiC often handle aggressive media better than ordinary steel-backed Babbitt.
• Contaminated or dry-start risk: choose materials that tolerate boundary lubrication, such as graphite, PTFE composites, or SiC, and pair them with robust oil seals to keep abrasive particles out.
• High speed with thermal limits: materials with high thermal conductivity, such as copper alloys or SiC, reduce hot-spot risk. For electrically driven pump assemblies, check motor bearing fit using deep groove ball bearings where rolling bearings are used.

Related Bearing and Seal Components for Pump Assemblies

Pump bearing material selection is only part of the assembly. The shaft, bearing housing, lubrication path, and seal system must be compatible. For severe or corrosive pump services, OiBearing offers ceramic bearings and related components that support long service life.

For water pumps, submersible pumps, and industrial process pumps, combine plain bearings or bushes with matching seals and oil seals to control leakage, contamination, and shaft wear.

Frequently Asked Questions

What are the most common pump bearing materials?

The most common pump bearing materials are metal sliding bearing materials such as Babbitt, tin-based bearing alloy, lead-based bearing alloy, and copper alloys, plus non-metal materials such as PTFE, graphite, rubber, cemented carbide, and silicon carbide.

Why is tin-based Babbitt preferred over lead-based Babbitt?

Tin-based Babbitt usually has better strength, hardness, and corrosion resistance than lead-based Babbitt. Lead-based grades are still used when cost matters and the pump service is not severe.

Which pump bearing material is best for high temperature?

For temperatures above the practical limit of Babbitt, consider bronze, PTFE composites, graphite, cemented carbide, or silicon carbide. The best choice depends on load, speed, corrosion, and lubrication.

Can pump bearings run without oil?

Some can. Graphite, PTFE composites, and silicon carbide are often used in dry-running or water-lubricated pump bearings. However, dry running still requires correct fit, thermal management, and compatible shaft material.

Do pump bearing materials affect seal life?

Yes. A bearing that overheats, wears, or allows shaft movement can damage seals. Select compatible pump plain bearings, shaft seals, and oil seals as one system.

Need help matching pump bearing materials to your operating conditions? Email [email protected] with your pump type, temperature, media, load, and speed for a practical selection recommendation.