Machine Air

[#2#]

I have two questions for all you guys and gals with air bearing machines.

Do you shut down your machine(s) overnight or over the weekend. I know a lot of you run 24-7-365 but we only have one shift monday through friday (I know, I'm lucky). I have always shut the machine down every night (electrical only, the air stays on). Some opinions on this please.

Also, I found out that our maint. dept. shuts down the compressor every weekend. Some opinions on whether or not this could cause problems please.

Thanks in advance!

[Gord Ashcroft]

My machine has air bearings and I leave it on 24-7.
I find that the air compressor being shut down on occasions has no effect on the CMM.
I do shut the machine down when I go on vacation and I know that the machine is not going to be used.
Hope this helps
Gord

[Paul Barriage]

As long as there is no vibration, or attempt to move your machine, lack of air shouldn't be a problem.

With that in mind, on that schedule, shutting down would be cool.

http://baggy3.info/2centani.gif

[T Miller]

I only turn of the pc thru the week. I leave the air on.

[Scirocco]

Same here,

We leave the air on even on vacation. PC shut down every weekend and holiday.
I the guide is clean when the air goes off there would be no problem. If there is accidantly some dirt or metal pieces on the guide plane and you shut the air off this could cause damage to the air bearing, and then you could have a problem.

Gr, Hans

[Jan d.]

There is a theoretical problem with turning off the machine. Air under an air bearing tends to cool (due to flow/pressure issues). This changes the temperature of the material it is running against, causing it to change shape. So purely in theory, it is better to leave your machine always on air so the temperature around the ways stays more constant.

Another issue that is raised a lot is that moisture/crud will settle in lines and then be blown out to just one spot when you turn the machine on. This can be an issue when you have very poor air quality.

But IF you have a WORKING air dryer, IF you keep your filters clean and IF you have a moisture trap plumbed into the line, I have never had any problems with a cold start.

So I always turned mine off. I was also running just 1 shift. I felt it was the economical thing to do. Maybe also the "green" thing. A CMM is a huge air leak in your system. Turning it off will save quite a bit of cash. Never had a problem.

Dirt under a bearing is not a real issue. The gap under a bearing is between 0.0002 to 0.0003", or 5 to 8 microns. Pressure and flow are such that very little gets trapped under it. And if dirt makes it under the bearing, it is a problem, regardless of whether the machine is on or off. That doesn't mean that you should NOT keep your machine clean. The cleaner the machine ways, the longer it will last.

My vote is for shutting the air down every night and starting from scratch every morning. But I must agree that if you can afford it, you can probably come up with some reasons to keep the air on.


Jan.