Inspec Insights

A Breath of Fresh Air

What is simplest yet the most often overlooked factor in properly functioning metrology equipment that can cause lots of damage if not handled correctly?

Compressed air….

Unlike a lot of today’s air tools that need oil to properly operate, most of the metrology equipment can be damaged and, in some cases even destroyed by air supply contamination.

One piece of equipment that is especially susceptible to problems from dirty air is your CMM.  The majority of CMM’s rely on air bearings propelled by the incoming air supply.  Those bearings allow the machine to glide effortlessly creating precision movements leading to more precise measurements. When the machine’s incoming air is contaminated with oil, moisture, and other pollutants the bearings to become clogged either partially or completely. 

Dirty bearings can lead to inaccuracies, sometimes greater than 20 times the OEM specifications.  This in turn can lead to recalling parts after they have been sent to your customers which results in a host of other issues.

Severely clogged bearings can also cause machine down time which is an expense no business wants to incur.


dirty air bearing

Example of a contaminated air bearing due to inadequate filtration prior to the air entering the CMM.

clean air bearing

Example of a clean air bearing


There are two primary ways to combat this issue.

First is to have good filtration directly before the CMM.  While an oil/water separator and air dryer directly off your air compressor helps, it is vital to have a good quality oil/water and particulate filter directly before the CMM as well.  Along with the filter system, in some cases, an air dryer can also be necessary to keep your equipment in top running order.

The second way to help prevent clogged air bearings is even more simple – clean them.  Weekly cleaning is a good rule of thumb, usually right before shutting down at the end of the week or start up at the beginning of the week.  By using isopropyl alcohol and a clean, lint free cloth you will remove any particles that do make it through the air filtration systems and help keep your machine floating along.

Most calibration houses can provide an air supply quality evaluation so you can see how you’re doing.

By adding these techniques to a regular calibration and maintenance program you can keep your CMM measuring accurately, help ensure product quality, and help extend the machine’s life.  

Leave a comment