How Machinable Is SAE 841 Sintered Bronze?

Q: Does SAE 841 have a machinability rating?

No. Machinability ratings compare alloys that are routinely machined; cast bearing bronzes like C93200 (SAE 660) carry a rating of 70 on that scale. SAE 841 is pressed to near-net shape and used as-sintered, so spec tables, including DBM's, list its machinability as N/A.

Q: Can sintered bronze be machined at all?

Yes, within limits. DBM machines sintered bar and plate stock to customer tolerances. Machined faces give up part of their surface oil path, so where self-lubrication at the running surface is critical, a pressed part is the better answer. Send the print and we will quote the right route.

Short answer: it is not rated for machinability, and that is by design.

SAE 841 oil-impregnated sintered bronze carries no standard machinability rating; DBM's spec table lists it as N/A. The material is pressed to near-net shape in a die and used as-sintered, because machining after oil impregnation smears the surface pores that store and release the bearing's oil. When a print calls for dimensions the standard catalog does not cover, the answer is a custom pressed part or machining from sintered bar stock, not cutting on a finished bushing.

Why Machining Is Limited

Sintered bronze earns its keep through its pore network: 18-22% of an SAE 841 part's volume is open space holding 24-27% oil by volume. In service, that oil feeds the running surface continuously. A cutting tool working that surface smears bronze across the pore openings and closes part of the oil path. The bushing still measures right; it just lubricates worse. That trade runs directly against the reason the material was specified.

The second reason is that machining is usually unnecessary. The compacting die produces the finished ID, OD, and length, so parts come out of the process at final dimensions. Secondary operations are limited to preserve the porous structure essential for oil retention and self-lubrication. For the full production process, see what is sintered bronze and how is it made?

What DBM Does Instead

Standard as-sintered sizes. 828 sleeve and 365 flanged bushing sizes plus thrust washers, all pressed to final dimensions. Start at the bronze bushing size chart or the sintered sleeve bushings page.
Custom pressed sintered parts. For production quantities in a non-catalog shape, DBM quotes custom pressing to your print. The part comes out of the die with its pore structure intact, no cutting required.
Machining from sintered bar and plate. Where a pressed shape will not work, DBM machines SAE 841/863 solid bar, cored bar, and plate to customer tolerances, with the material's lubrication trade-offs on the table before the quote.

SAE 841 Machining FAQs

Does SAE 841 have a machinability rating?

Why are sintered bronze bushings not machined after oil impregnation?

The bearing works by feeding oil from its pore network to the running surface. Cutting smears the bronze across those surface pores and closes part of the oil path, which degrades the self-lubrication the material was chosen for. The die already produces the finished dimensions, so machining is normally unnecessary as well as counterproductive.

Can sintered bronze be machined at all?

What does DBM do instead of machining SAE 841?

Three routes: standard as-sintered sizes (over 1,100 sleeve and flanged bushing sizes plus thrust washers), custom pressed sintered parts made to print for production quantities, and machining from SAE 841 or SAE 863 bar and plate where a pressed shape will not work. Most standard items quote same day.

Have a Print That Does Not Fit the Catalog?

Send it over. We will quote a custom pressed part or machined sintered stock, whichever suits the application.

Request a Custom Machining Quote