What Is A Porous Bearing
Porous bearing is a kind of bearing with the advantage of self-lubrication, its characteristic is that oil oozes out from the hole in the operation and lubricates on the friction surface, and once the operation stops, the oil is sucked into the hole again, so a small amount of oil can be used for long time lubrication. In addition, it does not glue with heat and is inexpensive, so it is now widely used in audio, home appliances, automotive electrical equipment, etc.
Porous Bearing Material Characteristic
- Bronze: Most common porous bearing: 90% Cu + 10% Sn. Wear-resistant, ductile, conformable, corrosion-resistant, with excellent lubricity and embeddability. Low cost; used from appliances to farm machinery.
- Leaded Bronzes: Reduced tin (20% less) and copper (4% less) than 90-10 bronze + 14–16% lead. Lower friction, resists galling when lubrication fails, higher conformability.
- Copper-Iron: Iron increases compressive strength but lowers speed limit. Ideal for shock and heavy loads; requires hardened shafts.
- Hardenable Copper-Iron: Copper-iron + 1.5% carbon; heat-treatable to Rockwell C65. High impact resistance; use with hardened-and-ground shafts.
- Iron: Low-cost with good bearing properties. Widely used in autos, toys, farm equipment, machine tools. Often blended with up to 10% Cu. High porosity for oil retention, good wear resistance; low PV limit on velocity. Use with hardened-and-ground steel shafts.
- Leaded-Iron: Improved speed capability while remaining low-cost.
- Aluminum: Runs cooler, tolerates misalignment better, lighter weight, longer oil life than bronze or iron. PV limit: 50,000 (same as bronze/iron).
Wholesale Porous Bearing | Material
The material of porous bearing is roughly divided into four kinds: copper, paste, copper-iron, and aluminum. The affinity of copper is good, the mechanical strength of iron is high, and copper and iron have a specialty of intermediate nature between the two. Aluminum is light in weight and has good heat transfer.
Most porous-metal bearings consist of either bronze or iron which has interconnecting pores. These voids take up 10% to 35% of the total volume. In operation, lubricating oil is stored in these voids and feeds through the interconnected pores to the bearing surface. Any oil which is forced from the loaded zone of the bearing is reabsorbed by capillary action. Since these bearings can operate for long periods without an additional supply of lubricant, they can be used in inaccessible or inconvenient places where relubrication would be difficult.
wholesale porous bearing
High Performance Porous Bearing
Main features of porous bearings.
Advantages: 1. Adapt to mass production
2. Elimination of cutting process, saving cost
3. Compared with rolling bearings, the sound is smaller
4. Self-lubricating effect, no heat gluing
5. No need or only need a small amount of oil supply
Disadvantages: 1. Not suitable for multi-species small batch production
2. Mechanical strength (compressive strength) is weak because of hollow holes inside the bearing
3 load capacity is small, most of the mixed lubrication or critical lubrication state, and therefore compared with the sliding bearing, the coefficient of friction is relatively large
Many Variations Are Possible To Meet Specific Requirements.
From 1% to 3.5% graphite is frequently added to enhance self-lubricating properties. High porosity with a maximum amount of lubricating oil is used for high-speed light-load applications, such as fractional-horsepower motor bearings. A low-oil-content low-porosity material with a high graphite content is more satisfactory for oscillating and reciprocating motions where it is hard to build up an oil film.
Porous-metal Bearings
High-Quality Porous Bearing
Porous-metal bearings are used widely in instruments and general machinery, in which their self-lubricating characteristics and load-carrying ability are very desirable.
Porous Bearing vs. Cast Bronze Bushings: Which is Right for Your Heavy-Duty Application? | BronzeOilless.com
In demanding industries like mining, construction, agriculture, marine, and heavy machinery, the choice of bushing can make or break equipment performance. Porous bearings (also known as sintered or oil-impregnated bronze bushings) and cast bronze bushings are two of the most widely used options. Both deliver excellent wear resistance and low friction, but they differ significantly in structure, load capacity, lubrication needs, and suitability for extreme conditions.
At BronzeOilless.com, we manufacture and supply both types — plus advanced graphite-plugged self-lubricating versions — to help you select the perfect solution.
Precision Porous Bearings | Oil-Embedded & Self-Lubricating
Porous bearings are made from sintered metal powder impregnated with oil (20–30% volume). They are self-lubricating: heat and rotation release the oil, which retracts via capillary action when the machine stops.
Pros: Maintenance-free, quiet, cost-effective, and ideal for hard-to-reach spots.
Cons: Lower strength due to porosity; limited to light/medium loads and moderate temperatures (<105°C).
Applications: Used in electric motors, automotive parts, farm equipment, and areas where relubrication is difficult.
Limitations in Heavy-Duty Use
High-Performance Cast Bronze Bushings
Machined from solid cast bronze alloys, these bushings feature a dense, non-porous structure. They offer superior strength and can be customized with oil grooves or graphite plugs for lubrication.
Pros: Extreme load/shock resistance, high heat tolerance (up to 260°C), and excellent durability.
Cons: Usually requires periodic lubrication, heavier, and slightly higher cost than porous types.
Applications： Ideal for heavy-duty machinery like excavators, presses, and marine equipment operating under high loads and vibration.
Porous Metal Bearing | Lubricating
The lubrication characteristics of porous oil-impregnated bearings are related to load capacity, friction coefficient, bearing temperature, etc. Its lubrication method is that the oil flows into the bearing from the bearing gap, flows and lubricates in the bearing, and at the same time flows into the bearing gap again. Porous oil-impregnated bearings can be lubricated in a wide range of forms, including from fluid lubrication to mixed or critical lubrication, as well as factors related to lubricating characteristics (such as the oil content inside the bearing, the permeability of the porous body, the porosity, the friction surface The material combination, the physical and chemical properties of the oil used for penetration, etc.) are more complicated than conventional plain bearings.
Why Upgrade to Cast Bronze Bushings from BronzeOilless.com?
While porous bearings are fine for light appliances, they often fail in heavy industrial machinery. At BronzeOilless.com, we replace weak sintered parts with robust Cast Bronze solutions designed for extreme performance. Here is why you should make the switch:
1. Solid Strength & Durability：Porous bearings contain tiny air pockets (voids) that weaken the structure.
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The Upgrade: We use casting processes to create bushings with 100% material density.
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The Result: Using premium alloys like C93200 and C95400, our bushings resist crushing and heavy impacts far better than sintered alternatives.
2. Precision Oil Grooves：You cannot machine oil grooves into porous bearings without ruining them.
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The Upgrade: We CNC machine custom oil grooves (Figure-8, Double-Loop, etc.) tailored to your needs.
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The Result: A consistent oil film that protects your equipment, even during low-speed, high-torque operations.
3. The JDB Graphite Advantage：Need a self-lubricating solution? Don’t sacrifice strength.
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The Upgrade: Our JDB bearings combine a solid cast bronze base with embedded graphite plugs.
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The Result: You get the maintenance-free ease of a porous bearing with the heavy-load power of solid bronze. Perfect for mining and high-temperature environments.
