What Is Sintered Bronze and How Is It Made?

Q: Is sintered bronze self-lubricating?

Yes. The open pore network holds oil (24-27% by volume in SAE 841) and meters it to the bearing surface in service, so the part lubricates itself without grease fittings or oil lines. This is the defining difference from cast bronze, which requires external lubrication.

Q: What is a sintered bronze bearing made from?

A sintered bronze bearing is made from bronze powder, roughly 90% copper and 10% tin in SAE 841, sometimes with a small graphite addition. The powder is pressed to shape in a die, sintered below the melting point so the particles bond, and vacuum-impregnated with oil.

Q: Is sintered bronze the same as Oilite?

Oil-impregnated sintered bronze bushings are often searched as "Oilite" bushings (Oilite is a registered trademark of its owner). DBM supplies equivalent SAE 841 oil-impregnated sintered bronze in standard sizes and as custom pressed parts.

A porous bronze that carries its own oil.

Sintered bronze is a bearing material made by pressing bronze powder into shape in a die and heating it below the melting point until the particles bond together. The finished part is deliberately porous: in SAE 841, 18-22% of the volume is open pore space, which is then vacuum-impregnated with oil. The result is a bearing that lubricates itself in service, with no grease fittings, oil lines, or maintenance schedule.

How Sintered Bronze Is Made

The process is powder metallurgy, and it runs in four steps:

Blend. Fine bronze powder is blended to the alloy specification. SAE 841 is roughly 90% copper and 10% tin (Cu 87.5-90.5%, Sn 9.5-10.5%), sometimes with a small graphite addition of up to 0.5%.
Press. The powder is compacted in a die under high pressure into the near-net shape of the finished part: a sleeve, a flanged bushing, a thrust washer, bar, or plate.
Sinter. The compacted part is heated in a controlled-atmosphere furnace below the bronze's melting point. The particles bond metallurgically where they touch, leaving a connected network of open pores between them.
Impregnate. The porous part is submerged in oil under vacuum. When the vacuum releases, oil fills the pore network: 24-27% of the part's volume in SAE 841.

Because the die produces the final shape, sintered bronze parts are typically used as-sintered rather than machined. That trade-off is covered in how machinable is SAE 841 sintered bronze?

Why the Pores Matter

The pore network is the whole point. It works as a built-in oil reservoir: as the shaft turns and the bearing warms, oil is drawn out of the pores to the running surface; at rest, the oil wicks back in. That cycle repeats for the service life of the bearing, which is why sintered bronze is the default choice for fractional horsepower motors, appliances, farm equipment, and power tools, applications where nobody is coming back to grease a fitting.

The limit to respect is temperature. SAE 841 has a maximum continuous operating temperature of 225°F; above that, the oil degrades or migrates out of the structure. And because the oil supply is what the pores hold, sintered bronze suits lighter loads and higher speeds better than heavy, slow, shock-loaded service, where cast C93200 (SAE 660) with external lubrication is the stronger fit.

SAE 841 vs SAE 863

DBM supplies two sintered bronze grades. Same copper-tin chemistry, different density, and the density sets the trade-off:

SAE 841

Standard density, 18-22% porosity
24-27% oil by volume, the most self-lubricating capacity
Tensile strength 14 ksi
The general-purpose grade for bushings, thrust washers, bar, and plate

SAE 863

Higher density, 11-16% porosity
14-19% oil by volume
Tensile strength 21 ksi, for higher-load service
Supplied as solid and cored bar for machined-to-print parts

Where It Shows Up in the Catalog

DBM supplies oil-impregnated sintered bronze as standard sleeve bushings, flanged bushings, and thrust washers, plus solid bar, cored bar, plate, and discs. Standard bushing dimensions are collected on the bronze bushing size chart. For custom shapes, DBM quotes custom pressed sintered parts to your print.

Sintered Bronze FAQs

Is sintered bronze self-lubricating?

What is a sintered bronze bearing made from?

Is sintered bronze the same as Oilite?

When should I choose sintered bronze over cast bronze?

Choose sintered bronze when the bearing must run without maintenance: no grease fittings, no oil lines, no re-lubrication schedule. Choose cast bronze such as C93200 (SAE 660) for higher loads and speeds, where external lubrication is available. Sintered bronze also has a 225°F maximum continuous operating temperature; above that, the oil degrades.

Need Sintered Bronze Parts?

Standard bushings, thrust washers, bar, and plate, or custom pressed parts to your print. Most standard items quote same day.

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