Composite dry sliding bushings... How good are they?

[Brunow]

Composite bushings are dry sliding (journal) plain bearings intended for radially loaded bearing arrangements and require a minimum of radial space. They permit oscillating or rotational movement. They are appropriate for all applications where freedom from maintenance is required or where lubricant starvation can occur. Composite bushings are available as standard in two designs which differ in the composition of the sliding layer: Composite B/E (fig 1) and Composite M (fig 2) bushings. The composition of the sliding surfaces is described in detail under "Composite dry sliding bearing materials".

I wonder how good they are... Any idea's?
And if you would oil them would they be better?

Thanks

[mxtras]

They have their applications and for those they work well. Just as with any bearing, they are suited for certain applications and not for others. What is your intended use?

Scott

[Brunow]

Using them instead of lineair ball bearings
http://www.vxb.com/Merchant2/graphic...01/lme25uu.jpg

For my xy and z axis (cnc router)
http://www.alignritetool.com/2000p.jpg <-- something like this.

[Brunow]

i found another site with a more clear picture:
http://www.igus.de/main_fs.asp?KATAL...DryLin&PRGR=50

[mxtras]

I would use them as an inexpensive alternative provided the machine was relatively small and light duty - sure. I would not use them for a high speed or highly loaded machine, though.

****edit - looking at the Igus bearings - those look far superior to a typical, inexpensive frelon lined bearing. They might actually handle a fairly decent load and properly protected and lubricated they might not offer as much friction at higher speeds, either.

Let's see what others have to say....

Scott

[svenakela]

For example the Igus-rails, composite bushings and anodized alu-rails, have very low friction but are not feasable because of too much play. Ball bearing bushings can be bought from eBay for a low price and will work a lot better.

Regards,
Sven

[mxtras]

I agree, but I think with proper - possibly even modified application, it would be possible to get a fairly tight system.

I would also suggest running them on hardened, ground, polished, supported and appropriately sized rods - not anodized aluminum.

Scott

[RICHARD ZASTROW]

If you intend to lubricate the composite material, make sure the material you choose will tolerate the lubricant. Some are made for "wash-down" applications and will tolerate water, some soaps and some detergents but not oil. Some will tolerate most oils but not all oil based lubricants. Check with the composite supplier as to the correct lubricant if any.

[svenakela]

Originally Posted by mxtras I agree, but I think with proper - possibly even modified application, it would be possible to get a fairly tight system. I would also suggest running them on hardened, ground, polished, supported and appropriately sized rods - not anodized aluminum. Scott

Igus rails are made of alu. They last, I can guarantee that.
But all kinds of slide bearings have a play that multplies in a router system and they (not all though) must be placed correctly at the design stage of the machine as they have a potential risk of "locking". These problems doesn't exist in a ball bearing situation.

Regards,
Sven

[sowisc]

At my last job they had an old Hendrick overhead panel saw. The saw carraige had 2 bronze bushings each on 2" diameter hardened steel rails. The saw was probably 15 to 20 years old, and there was more play from the rails twisting than there was in the bushings. You could twist the rails simply by pushing on the bottom of the blade. That said, after years of neglect, the bushings were getting worn out and causing poor cut quality.