Often we ask the machine operator how often he checks his machines lubrication system. The normal reply is that it’s checked every time the alarm goes off in the control prompting his attention. He finds the filthy funnel that everyone uses for everything, he pours the lube (maybe the correct kind) through the filthy funnel and the alarm resets. If this plan is not bad enough we’ve all seen the machine sitting with the funnel either sitting to drain in the machine lube tank, or the funnel is dropped into the five gallon bucket of oil that he poured into the machine. This is trapping grinding dust and shop contaminants into your clean oil.

How your system works:
On most CNC machines that use oil instead of grease a centralized oil system distributes the oil from one pump. The oil can go through several banks of distribution blocks. Oil leaves the pump and goes into the block under pressure. A pressure switch normally looks for a pressure signal. Each of the small injectors can send a measured dose of oil to your ball screws, ways or thrust bearings. These injectors are very sensitive to dirt or contaminants. If the injectors become contaminated they can “stick”. This means the machine sees pressure, but oil is not delivered through that injector. The operator never sees the alarm and does not have to fill the tank as often. He is much more likely to complain about filling it too often instead of less frequently.


The lubrication system on your CNC machine has several built in safeties. Filtration, low lube level and pressure switches are normal on most machine tools.

The lube in the tank can build sediment over time. The tank below is a real example of a machine in production. The sediment will settle to the bottom of the tank and needs to be cleaned periodically.

The sediment below came from this tank. The whole cleaning process took less than thirty minutes.

The filter in this tank was completely packed with this sludge.

Years ago we had a box way machine become contaminated. The operators couldn’t remember the last time he had added oil. The ball screws and the ways were damaged to the point of us recommending replacement of the machine.
The next time you ask about has your operator “checked” his lubrication, take a closer look.

You don’t have to be a lube “Goo”rue

Every machine is different, so check your manual. It takes less than 30 minutes to increase the life and productivity of your machine and you will be a lube guru.