A coordinate measuring machine is a high-precision measuring machine used to measure the geometry of physical objects by sensing discrete points on the surface of the object with a probe. Probes are of various types, mechanical, optical, laser and white light. (Definition Source: Wikipedia)
Moisture in air causes condensation and corrosion on the parts of the control measuring machine, especially if the parts consist of iron. Additionally, control measuring machines have granite tables which are hygroscopic in nature, so humidity variations affect their dimensional stability and make them unsuitable for use in CMM’s of the highest grade.
To understand corrosion effects on the control measuring machines better, pls find the below table:
(Table Source: Environmental Effects on Coordinate Measuring Machine Measurements)
Laser wavelengths in CMM’s also tend to change with the changes in air temperature, pressure and humidity, and it is often assumed that linear measurements taken with lasers are accurate. There are potential measurement errors when the wavelengths change due to uncompensated changes in air temperature, pressure and humidity. (went through the points where they have mentioned humidity in the document and tried to put it in my own words, you can go through too to add your input : http://www.renishaw.ru/media/pdf/en/52da1777b4a14a64a83ac566a665a11f.pdf )
So, factors like condensation, corrosion and change in laser wavelengths lead to inaccurate measurements, affect the overall working of the machines and reduce their lifespan. Correcting the damage caused to the machine will be expensive and lead to unexpected downtime.
Therefore, to meet accuracy expectations and protect the high-precision measuring machine from damage, it is very crucial to observe a controlled environment having temperature and humidity levels that meet the standards, which will help in achieving maximum measurement precision of the machine.
Dehumidifiers prevent condensation and corrosion on the machine. Dehumidifiers are a preventive solution towards protecting the coordinate measuring machine from moisture damage. Dehumidifiers maintain consistent and controlled humidity levels that contribute to an ideal environment for obtaining accurate measurements.
*Standard air is defined as air with a pressure of 1013.25 mbar, a temperature of 20°C, and a relative humidity of 50%
And Portable Dehumidifiers help maintain close to standard conditions wrt RH.