THK Rail lubrication

[PEU]

I received my last pair of THK rails and noticed something new: this new set moves far more easy than the brand new ones I have from the previous purchase.

Looking carefully at the lubrication of the items I notice that they are different.

So my question is: What kind of grease/lubricant is recommended for THK SHS rails and blocks.

I know THK sells lubricants, Im looking for alternatives.

Thanks


Pablo

[mxtras]

DO NOT use 'regular' grease. A thin bodied white lithium works well and is easily obtainable.

The use of regular greas will likely cause premature failure. The balls can not circulate properly in the presence of the higher viscosity grease and will 'skid' along the rail causing excess wear on both the rail and the block. Been there, wrecked that as it has been said. Expensive lesson....for my employer, that is.

Using light oil is also an option for loads less than half the recommended maximum for the bearing. Use oil for higher speeds based on the bearing's rated specs. You would want to set it up on a one shot system and lightly oil them every 10-15 minutes of actual use. THis is not a bad idea at all as it would continually purge any crap out of the bearing. You could even automate the lube system. The bearings will run a bit louder but will offer far less resistance than using even the light bodied grease.

ALSO - along the lines of lube - for a machine in a dirty environment, I would strongly recommend plugging the screw holes in the rail. The caps from THK are cheap (.27 USD) and they will keep the crap from sneaking under the seals. Or you could use Bondo or something. You probably do not want to use something that you couldn't remove (epoxy) in case of a problem that would require removing the rail from the structure.

You might also consider plumbing the lube points to be easily accessable. The threads in the blocks suck (in my experience) and have a way of giving out quickly - especially if the blocks have options added to the sealing system - such as additional wipers and scrapers. If you were to put a tube fitting in place then plumb it with plastic tubing to a convenient location it will lessen the chance of destroying the threads in the block and promote good lubrication intervals . Just a thought!



Scott

[MikeAber]

DO NOT use 'regular' grease. A thin bodied white lithium works well and is easily obtainable.
Scott

Great post Scott!

Thank You!

[PEU]

Scott: Thank for the advise!, I almost ruined a block in the meantime before your post appeared. How?, same mistake, by using a thick grease. Luckily enough I managed to keep all the balls and painstakingly put them back together (2 hours).

You can't imagine how much I sweated putting all the balls together inside the rail...

I think I will need to do some more rounds of very fluid lube until they run smooth again.


Most of the blocks I have, have the way wipers installed, but yes, they are attached with only 2 screws, the other 2 are not there, so covering them is not a bad idea.

Im thinking on using Molykote BR2 Spray as the lubricant, what do u think?

Thanks a lot!!!

Pablo

[mxtras]

Being a bit short on time here, I cannot really research it completely to say for certain that I would use the BR2. It lithium based but it's mineral filled, too - - not sure but at this point I would look into a pure lithium soap based grease with a very light viscosity - maybe like the BG-555. Sorry for the lack of research...I love this kind of stuff - but like I said - I am short on time.

I would steer away from the teflon/aluminum/copper/monkey hair filled stuff - they can eventually cake up in non-pressurized, non-circulating lubrication environments. Over time, this can plug the ball recirculation guides and channels. It's important to keep those little balls moving and happy. It's different in a car engine, for example, where you have compressive loads but a constant purge of pressurized fluid to keep things moving and the additives completely dispersed.

If oiling, please do yourself a favor and consider doing the one shot/plumbing thing. You will be thankful eventually.

Here's a couple of links to info on the BR2 - you can probably find more (you probably already have!):

http://www.astbearings.com/p-lubes-greases.php
http://www.dowcorning.com/content/pu...olykote&DCWSS=

I am glad I could help and sorry I am so short on time - heading to Colorado for a race in a few hours! (motocross, of course)

Scott

[CNCRob]

Hey Scott, You just made me fell better. I have been using white lithium grease on my rails and wasn't really sure if I was suppose to or not. I now feel alot better knowing I am suppose to. Thanks-Robbie

[mxtras]

I am VERY glad to know that my mistake (about 8 years ago) taught me and that I was able to convey the info. My mistake cost my company about 8K in parts and about 26K in lost production. OOOPS! Stick with lithium soap grease - that was the result of my research into the failure at the time.

This site is awesome. Thanks for the site, Paul!

Scott