To grease or not grease

Hi,

I am cleaning up my new SX3 and the X axis bearings nearest the handle has back to back thrust bearings in a tube about 50mm long. In the top is an oil nipple and the manual says to oil it.

The bearings have been packed with black grease, hopefully moly not dirt.

Should I do the same and grease the bearings before fitting, or just use oil?

Adrian

Grease according to Arc's guide

Though my X3 has never had them out and they just get an oil once in a blue mood and seem fine after 13yrs of use!

Edited By JasonB on 16/05/2020 13:27:24

What an idiot I am, I have been looking at that doc for other things, never thought to read the bit about the bearings.

Although I am still wondering about the merits of oil or grease lube for bearings. Obviously they both work, but when would you choose one over the other. Thinking of wheel bearings, they are greased and then run for years unmaintained.

Adrian

Grease is fine for low(ish) speed applications, in which dirt can be kept out. Too much grease and/or too high a speed will cause the bearing to run warm or hot. This isn't going to happen in this application, in which retention of lubricant is probably the prime concern. Oil has a habit of dribbling away. So grease is good.

Oil is good for high-speed bearings (eg high-speed spindles), particularly if it circulates. It will carry heat away from the bearing, and, with luck, muck too. But few machines we are likely to come across will have oil pumps...

Re pack them with grease. It was originally engineered for grease. People who use grease where oil is intended to be used get to buy new bearings sooner than expected.