“Your ball screw is lubed for life, so it’s maintenance free!”
Have you ever heard such a claim from your vendor? If so, you should be wary. Like most things that sound too good to be true…
Every ball screw is pre-lubricated at the factory. The on-going maintenance cycle depends greatly on the application. For most machine tools, Steinmeyer recommends the first ball screw lube check at 500 hours. Depending on the results, customers may set future intervals shorter or longer.
Some vendors advertise ball screws with that are “lubed for life” at high loads. This sounds fantastic: maintenance free operation and high performance! But if you stop to think about it, high loading naturally decreases the life. So this combination is possible not because the maintenance interval is so long, but because the life is so short!
This logic reminds me of when Bugatti announced a 1001 horsepower sports car some years ago, with a top speed of 200 MPH. If you go flat out, you’ll run out of gas in 15 minutes. But don’t worry, because the tires will melt in 12 minutes!
Other vendors advertise lubrication units mounted inside the nut. These are usually plastic rings impregnated with oil. Such an approach may very well extend the early maintenance intervals, but they eventually run out. At that point, you are forced to send the screw back to replace the lubrication unit, or revert to typical lubrication methods. Furthermore, you have no choice over the lubricant; you are stuck with whatever is in the plastic. Given these caveats, you have to ask whether this approach really gives you any net benefits.