Is bronze always the better choice over iron?

Not always. BP25 bronze wins on speed, conformability and corrosion resistance and covers the widest size range, which makes it the sensible default. But FP20 iron is harder and more economical and performs better under slow, heavily loaded or oscillating duty in a non-corrosive environment. Match the grade to the actual load, speed and setting rather than assuming bronze is universally superior.

Can I machine a blank and still keep the self-lubricating property?

Yes, provided you respect the porous structure. Machine outside diameters, lengths and features conventionally, but bring the running bore to size by burnishing or ball-sizing rather than heavy reaming, which would close the pores. Avoid solvent contamination during manufacture, and re-impregnate the finished bearing with the correct oil so the pore network is fully recharged before it enters service.

Which impregnation oil goes with which grade?

BP25 bronze and FP20 iron both take TURBO T100 as standard, while SO16 alloy uses its dedicated METADOP oil. For special conditions, high-temperature PE1116 covers -40 degC to +150 degC and food-grade PE1152 suits hygienic equipment. The oil is chosen for the environment and matched to the grade, so confirm the pairing when specifying, particularly for SO16 and for temperature-critical duty.

BP25 Bronze vs FP20 Iron vs SO16: Choosing the Grade

Bushingo offers three self-lubricating sintered grades - BP25 bronze, FP20 iron and SO16 alloy - alongside machinable bearing blanks and friction plates. Each is a porous, oil-impregnated matrix, but they differ in hardness, corrosion resistance, speed capability and, importantly, the form in which they are supplied. Choosing between them comes down to load, speed, environment, and whether a standard bush or a machined custom geometry is required.

Characteristic	BP25 bronze	FP20 iron	SO16 alloy
Matrix	sintered copper-tin bronze	sintered iron	sintered alloy
Relative hardness	softer, conformable	harder	alloy-dependent
Corrosion resistance	good	lower	grade-specific
Speed capability	higher	lower	machined to duty
Supplied as	finished bushings and blanks	finished bushings and blanks	bearing blanks only
Impregnation oil	TURBO T100	TURBO T100	METADOP

BP25 sintered bronze - the general-purpose default

BP25 is a sintered copper-tin bronze and the natural first choice for most applications. The bronze matrix is relatively soft and conformable, so it beds in against the shaft and tolerates slight misalignment; it resists corrosion well and carries the highest continuous sliding speed of the three grades. It also has the widest catalogue coverage: cylindrical references from 2 mm to 125 mm bore across three size bands, and flanged references from C03 to C60 with an integral collar for axial location. BP25 is impregnated with TURBO T100 as standard, with food-grade PE1152 and high-temperature PE1116 (-40 degC to +150 degC) available where hygiene or temperature demand it. If an application does not have a specific reason to choose otherwise, BP25 bronze is the sensible default.

FP20 sintered iron - load and economy at low speed

FP20 is a sintered iron grade. It is harder and more economical than bronze but has lower corrosion resistance and a lower speed ceiling. Its strengths appear at low sliding speed and higher unit load, and in oscillating or intermittent duty where the mean velocity stays modest - the hard iron matrix resists surface deformation under concentrated load. Bushingo supplies FP20 as cylindrical bushings from roughly 3 mm to 100 mm bore and as flanged references up to 60 mm bore, impregnated with the same TURBO T100 oil as BP25. Choose FP20 when the duty is slow and heavily loaded, when cost sensitivity is high, and when the environment is not aggressively corrosive.

SO16 alloy - machined-to-order bearings

SO16 is a self-lubricating sintered alloy grade, and it is positioned differently from the other two: Bushingo supplies it only as bearing blanks - hollow and solid - rather than as finished cylindrical or flanged bushings. It is served by its own dedicated impregnation oil, METADOP, distinct from the TURBO T100 used for bronze and iron, which reflects a different matrix chemistry. In practice SO16 is selected when a component needs a self-lubricating alloy other than plain bronze or iron and will be machined to a custom geometry from a blank rather than drawn from the standard bush range. As with any porous bearing, the finished part should be sized and re-impregnated appropriately after machining, and its permissible load, speed and temperature confirmed for the specific duty.

Bearing blanks for non-standard geometry

All three grades are available as machinable blanks when a standard bush size will not do. Hollow blanks come in stepped sizes from about 38 mm bore / 70 mm outside diameter up to 175 mm outside diameter, at 120 mm length; solid blanks run from 20 mm diameter x 40 mm long up to 145 mm diameter x 120 mm long. From these, bores, outside diameters, lengths, oil grooves and special profiles can be machined to a drawing. The porous-material rules still apply: cut on the outside and the bore with sizing rather than aggressive reaming where the running surface is concerned, avoid solvent contamination, and re-impregnate the finished bearing so the pore network is recharged before service.

Friction plates for flat and thrust sliding

Where the motion is flat rather than rotary - slideways, thrust faces, wear pads and guides - a bush is the wrong format. Bushingo's Metagliss self-lubricating friction plates are supplied as 375 x 375 mm composite plates in thicknesses from 4 mm to 20 mm and in three grades (M10, M60 and M90), to be cut and fitted as sliding surfaces.

Choosing in practice

Default to BP25 bronze for general rotating duty, higher speed, corrosion resistance and the widest ready-made size range.
Choose FP20 iron for slow, heavily loaded or oscillating duty and cost-sensitive builds in non-corrosive environments.
Specify SO16 alloy when a machined custom bearing is needed in a self-lubricating alloy beyond bronze or iron - remembering it is a blank-only grade with METADOP oil.
Reach for hollow or solid blanks for any non-standard geometry, and Metagliss plates for flat or thrust sliding.