Self-lubricating chain

These rollers improved performance by allowing the chain to articulate more smoothly into sprockets and protect the sintered bushes.

[citation needed] Powdered metal sintered bearings (in the case of roller chain, the bushes) are self-lubricating because their porosity is impregnated with lubricants during the manufacturing process.

In use, frictional heat causes the lubricant to expand and flow out of the pores, forming a film between mating parts.

The initial compaction to a large degree dictates the density, shape, dimensions, and mechanical properties of the finished part.

[9] It is essential that the pores form an interconnected system of controlled size and volume, so that oil is supplied to the entire bearing surface.

(Chain companies like Tsubaki and Renold PLC also offer sintered bushes impregnated with food grade lubricant.)