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Lead Screws International

2101 Precision Drive

Traverse City, MI 49686 USA

Toll Free: (800) 678-0726

Phone: (231) 947-4124

Fax: (231) 947-3851

BALL SCREW LUBRICATION

There is no such thing as a permanently lubed ball screw. Lack of lubrication will reduce the life and performance of the ball screw and the entire machine.

There are two types of lubrication (A) Oil, and (B) Grease.

(A) The best lubrication is light oil. The best method of application is by a Trabon type system directly into the ball nut. The ball nut has the greatest wear with the balls recirculating around the screw. We recommend light oil in order to flush the contaminants out of the nut. The pressure type system will see that the oil gets into the nut. The question of how much oil, should be answered with the question of when to oil. Use a timer so that the oil is applied on a random basis as the nut travels over the length of the screw. It is not beneficial to have the ball screw being lubed at only a given point in the cycle. The rest of the screw and possibly the nut will then lack lubrication. We recommend light spindle oil or light way lube. You should be able to take your hand and grab the screw after a pass and have an oil film on it. If your hand is dry then you have a potential problem.

A few customers will use a drip system on to the screw where the ball nut will pass over the location. This is not an efficient way and will not flush the ball nut. The same could be said about a mist system.

(B) We are not in favor of grease or a heavy oil. Grease holds the contaminants in the nut and will therefore lead to the possibility of the material acting as a lapping compound. Grease in many cases will turn hard as we have seen in the ball screws that have been sent in for repair. You need to flush the contaminants out of the nut in order to maintain the life of your system.

Other problems:

1. Lack of lubrication will shorten the life of the ball screw, increase tolerance, etc.

2. Contaminated lubrication is as bad as no lubrication.

3. Too much lubrication or the wrong type can cause the balls to slide instead of rolling.

4. Certain spray can lubricants and rust preventives become gummy and turn to varnish with time and exposure. The ball bearings slide instead of roll.

5. Coolants are a major maintenance problem to the entire machine. Synthetic coolants with a paraffin base cause rust and a build up of paraffin. I have seen slides lifted up as much as 0.010" over time. All lube ports were plugged. Every time the machine was shut down, a build up of material and rust occurred. You need to have a good pressurized system to have any hope of overcoming this type of problem. A number of machine builders will not honor warranty of their machine under this condition. The ball screws, slides, and spindles will react different over the course of the day as the matter builds and dissolves.

It is important that you instruct your customer or operator to cycle the equipment even though he has no production in order to keep lubrication in the ball screw, slide and spindles. Ball bearings will get a flat spot from sitting if it is not rotated from vibration and lack of lubrication at that contact point.

CATALOG

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