Really basic lubrication question?

Hi,

I suddenly realised I am ignorant over when grease as opposed to oil should be used and especially metal to metal applications

Yes grease is less fluid and may hang around longer and has more mass but is that it?

Anyone care to give a better explanation?

Chris

Edited By Chris TickTock on 05/01/2020 11:18:52

Grease is oil in a soap base. Grease will not always flow to where it is required but will persist where oil might be lost.

Have you explored the ‘net via google or some other search engine?  Differences are well documented.

Edited By not done it yet on 05/01/2020 12:00:06

Chris

Grease is generally used for slow moving assemblies such as Morris Minor suspension joints.

Oil tends to be used for faster moving things such as lathe spindle bearings.

Having said that there are no hard and fast rules, for instance the saddle lubrication on an Alexander milling machine must be lubricated by oil as the galleries are fed by wicks. Grease would just bung everything up and disaster would ensue. The same applies to Myford lathes, I always use oil and not grease on the slideways.

So it is really a matter of following manufacturers instructions, and if they are not available the design of the assembly should be checked to see how the lubricant gets to where it is needed.

Failing that ask someone one here if you need something more specific.

Phil

Thanks Guys, from my clock forum i know there are strong opinions as to the 'right' lubricants for clocks. I have google about and for lathes oil seems in grease out apart from certain places. Grease will keep swarf so I get that. I personally like synthetic Oil so will use that.

Chris

Grease is usually 'out' unless specifically called for. It's handy for situations favouring a sticky semi-solid lubricant, such as power gearing. It's also good for preventing corrosion because it doesn't drip.

Generally, lubrication has tended to move away from high-maintenance systems needing men with oil-cans and grease guns to pumped and sealed-for-life systems. In broad terms oil has tended to replace grease as the preferred lubricant.

For lathes and machines with slide-ways, especially vertical slide-ways it's a good idea to use 'Way Oil'. Being sticky, it's not pushed out of the way by the saddle. Personally I don't bother, instead using ISO32 Hydraulic Oil for almost everything. Avoid certain EP oils if your machine has bronze bearings or any brass parts : the chemical added to improve pressure performance attacks Copper. The label carries a warning.

3-in1 is a general purpose household oil good for door hinges, garden tools and general cleaning. Not particularly useful in a workshop I feel, and - like WD40 - deadly to clocks. 3-in-1 (and similar concoctions) contain vegetable oil that gums up over time and collects grit. This murders fine mechanisms like clocks by stressing and wearing the mechanism. WD-40 commits the opposite sin; it contains a light oil that washes out the pivots. At first the clock is lubricated by a thin layer of oil left behind but this soon evaporates leaving a sticky water-repellent layer that has much the same effect as 3-in-1, except the bearing is run dry.

Always use the correct type of oil on a clock or similar mechanism; workshops tools are far less fussy.

Is there a particular reason you favour synthetic oil? I suggest the particular specification and purpose of the oil is more important. Most Synthetic oils are formulated to improve their performance at high temperatures. This is rarely needed in the workshop and the additives might be positively harmful. Good old-fashioned oils - like plain ISO32 - are more appropriate. Although I tend to avoid Motor Oils because they contain additives suited to boiling hot engines rather than cool lathes, of course any oil is better than none.

Dave

I personally like synthetic Oil so will use that.

Your choice, but remember that most oil is total loss (apart from gearboxes) on our machines. Synthetics have other characteristics that make them superior in some aspects, but rarely any better than dino oils for total loss systems.

I’m not sure of low speed for grease. We used grease in machines with two pole motors - faster than most hobbyist lathe spindles. But, as always, there are exceptions. Most small ‘ball’ bearings have sealed versions which are prepacked with grease, for lifelong lubrication.

The lathe gets semi synthetic 5W40 motor oil for everything, and both mills with taper roller spindles are greased with Lithium grease which is also used in car wheel bearings. The slideways of the mills get slideway oil and the leadscrews get spray motorcycle chain grease.                                                                                                                Plain bearings can be oiled or greased, but sintered bronze, being porous, is better off with a little oil from time to time which soaks into the surface far better than grease.

I would avoid Three In One oil, unless just for wiping on to surfaces with a rag to temporally rust proof them. WD40, AC90 Plus Gas and the like are good for penetrating oils and on aluminium when it is being turned or milled to stop it welding to the cutting tools. I use CT90 tapping oil when cutting threads, single pointing on the lathe, or when using taps and dies. I also oil my throat with Badger beers.

Edited By old mart on 05/01/2020 15:04:26

Castrol edge . If it's good enough for the Jaguar it's good enough for the lathe. Had a bottle so why buy anything else. Synthetic oils cling longer too.

I most often use something like Agricastrol or equivalent. A universal hydraulic/lubricating oil. Cheap as chips - a mate buys it by the 200litre drum.🙂 Thin, medium or thick - dependent on the application.

Thanks Guys, really interesting for me, lathe lubed up ..time to wash up.

Chris

Hi, grease can if it is not constantly being move by what it is lubricating, dry out. Bearings on car stub axels are normally grease lubricated as are bearings with rolling elements, as used in plummer blocks, flange and take up, i.e. Cooper, SKF, FAG etc. If your lathe is not a geared head one and has ball or tapered bearing on the spindle, they are likely to be lubricated by grease.

Regards Nick.

thanks Nick, I think I will have to go away and do some reading...thanks mate

Chris

There is no simple questions or simple answers when it comes to lubrication, there is a whole science behind it! The base question grease or oil depends on many things, relative speed of the surfaces and load being the first considerations. Many high speed applications can use plain bearings (turbochargers being a case in point where speeds are up to 50krpm) with plain pressure fed oil lubricated bearings. Highly loaded spherical roller bearings such as the SKF SOFN series of blocks do not use grease but oil. The key to successful lubrication is the surfaces remaining separated by the lubricant. You need to be careful with grease in roller bearings, the SKF Cooper split roller bearings will run excessively hot if there is too much grease in the casing, not always a case or more being better!

No easy answers!

Paul.

I read somewhere that motor engine oils are not recommended for use in or on machine tools because of some of the additives can cause damage. Unfortunately it didnt explain how or what damage and of course you have to ask is it true, I don't know...?

Edited By Ron Laden on 06/01/2020 05:20:05

What are lathes made of? What are engines made of? Much the same, I would guess?

One is certainly buying additives needed for high temperature, acidic combustion products and a host of others in motor oil - but not needed in a total loss, cool application for a lathe. So, throwing away money is the main downside, I would guess.