Can a self-lubricating friction plate replace a greased slideway directly?

Often yes, and it removes the relubrication schedule, but treat it as a design change rather than a drop-in. Check the counterface finish, ensure flat rigid backing so load spreads across the face, and confirm the plate's load and speed suit the matrix grade. The porous surface must be free to bleed oil, so avoid the grease grooves and clamping arrangements a greased flat tolerates.

How should the mating counterface be finished?

Run the plate against a hard, ground steel surface with a moderate, controlled roughness. Too rough abrades the plate and wipes the film; too smooth can starve the mixed-lubrication mechanism. Keeping the harder, better-finished surface as the counterface protects the sintered plate.

Which matrix should I choose for a slow, heavily loaded slide?

Favour FP20 sintered iron for economy and static load capacity at low speed, or BP25 sintered bronze where lower friction and better heat conduction are wanted. Pair either with a boundary-supporting oil such as METADOP, because slow heavily loaded sliding runs largely in the mixed and boundary regime where film strength matters most.

Self-Lubricating Friction Plates & Slideways

Rotating bushings get most of the attention, but a large share of sliding-contact problems are flat, not cylindrical. Thrust faces, gib strips, wear pads, cam followers, press tooling and machine slideways all rely on plane sliding surfaces, and they suffer the same enemies as any dry contact: starved lubrication, stick-slip and adhesive pick-up. Self-lubricating friction plates and slideways apply the same oil-impregnated sintered principle used in Bushingo bushings to flat and linear duties, giving a bearing surface that carries its own lubricant across a plane rather than a bore.

The same porous principle, in a flat format

A sintered friction plate is a porous metal panel or strip, impregnated under vacuum so the interconnected pore network holds an oil charge. As the mating surface slides, local heating and contact pressure draw oil to the interface to form a mixed-lubrication film, and when sliding stops the oil is drawn back into the matrix by capillarity. The physics is identical to the rotating case; only the geometry changes. That has two practical consequences. First, lubrication is delivered uniformly across the whole sliding face rather than from discrete grease points or oil grooves. Second, the plate keeps working through the low-speed and oscillating regimes where a hydrodynamic film never fully develops and conventional flats are most prone to stick-slip.

Why flats fail, and how a bleeding surface helps

Plane sliding contacts fail in characteristic ways. Boundary starvation at reversal points on a reciprocating slide leaves the ends of the stroke dry. Stick-slip - the juddering caused by static friction exceeding kinetic friction - spoils positioning accuracy on machine tools and instrument stages. Adhesive transfer, where asperities cold-weld and tear, scores both surfaces. A self-lubricating plate attacks all three: the internal oil keeps the boundary film replenished at reversal points, the persistent film lowers the gap between static and kinetic friction so motion is smoother, and the oil barrier suppresses the metal-to-metal adhesion that starts scoring. The result is quieter, more repeatable linear motion with a low and stable coefficient of friction.

Material choices for plates and slideways

Plate and slideway duty spans a wide load and speed range, so matrix selection follows the same logic as bushings:

BP25 sintered bronze - the workhorse for moderate to higher loads and speeds. Its good thermal conductivity carries frictional heat away from the interface, and bronze runs kindly against steel counterfaces. It suits thrust washers, wear pads and slideway facings where consistent low friction matters.
FP20 sintered iron - a cost-effective choice for lower-speed, higher-load or heavily loaded intermittent duty. Iron-based plates offer strong load-bearing capacity for slow slides, presses and indexing mechanisms where economy and static capacity outweigh top speed.
SO16 alloy - an alloy grade for applications needing particular tribological or environmental characteristics, where the standard bronze or iron matrices are not the best fit for the counterface or duty.

The oil charge is then matched to the motion. Slow, heavily loaded or oscillating slides favour a higher-load, boundary-supporting oil such as METADOP; long continuous or warm-running duties favour the oxidation stability of TURBO T100; general plate work runs well on PE1152.

Design and mounting guidance

A self-lubricating plate only performs if the surrounding design lets it bleed and reabsorb oil. A few principles apply:

Counterface finish. Run the plate against a smooth, hard steel counterface. Too rough a mating surface abrades the plate and scrapes the film; too mirror-smooth can starve the mixed-film mechanism. A ground finish in a moderate roughness band is usually the target for this class.
Even pressure distribution. Support the plate on a flat, rigid backing so contact pressure is spread across the face. Edge-loading or a distorted mount concentrates load, thins the film locally and drives early wear at that spot.
Retention without crushing. Fix plates by their mounting features, not by clamping across the porous face. Over-clamping closes surface pores and chokes oil delivery exactly where it is needed.
Debris and contamination. Keep abrasive swarf off the slide. Because the surface is porous, hard fines can embed and become a lapping compound. A wiper or simple cover greatly extends life in dirty environments.
Thermal headroom. Sintered bronze plates of this type typically run to around 100 C continuous with mineral oil charges; keep the interface within that band, remembering that continuous high-speed sliding generates its own heat.

Where they earn their place

Self-lubricating plates and slideways are most valuable where relubrication is impractical, undesirable or unreliable: enclosed mechanisms, food and clean applications that cannot tolerate grease migration, slow-cycling machinery that never builds a hydrodynamic film, and precision stages where stick-slip would wreck accuracy. In each case the appeal is the same as the bushing - the lubricant is built in, delivered uniformly across the sliding face, and requires no maintenance intervention over the design life. Specify the matrix for the load and speed, the oil for the motion and temperature, and the mounting to protect the porous surface, and a flat sintered bearing will deliver the same quiet, maintenance-free service as its cylindrical counterpart.