Compressed air: More than oil-free, dry and clean

Modern CAD/CAM milling and grinding machines require a stable supply of compressed air to function optimally. The following tackles a solution to achieve consistent, high-quality compressed air in a dental facility.

A dental facility cannot operate without a dependable supply of compressed air. Whether it be a simple handheld air nozzles or modern CAD/CAM systems — oil-free, dry and clean compressed air is an essential ingredient in the success of a dental laboratory.

But in the advent of digital technologies, which includes milling and grinding machines in the dental laboratories, these simple requirements to the compressed air are not sufficient anymore.

The present manufacturers of CAD/CAM systems frequently ask for a clearly defined quality of compressed air. Most of the time, they look for the 1-4-2 classes of quality.

These classes refer to the ISO 8573-1:2010 for compressed air — the international norm that defines the purity classes and regulates how much water, oil and particles are allowed to remain in the compressed air after treatment.

These three characteristics are the following:

Class 1 particles

Maximum particle count per m3 of a particle size with d [µm]*)

0.1 < d ≤ 0.5                   ≤ 20,000

0.5 < d ≤ 1.0                   ≤ 400

1.0 < d ≤ 5.0                   ≤ 10

Class 4 water

Pressure dew point, in °C

≤ +3 °C

Class 2 oil

Total oil concentration (liquid, aerosol + gaseous) [mg/m3]*)

≤ 0.1

*) At reference conditions 20°C, 1 bar (a), 0% humidity

Modern CAD/CAM milling and grinding machines represent a significant investment, which needs to be amortised as swiftly as possible. In order to achieve this, the systems should run around the clock, ideally even at weekends.

But to function seamlessly, this equipment requires a stable supply of quality compressed air at a minimum pressure of seven bar.

If the requirement regarding pressure and air flow is fulfilled, the existing compressed air system can be equipped with filters and a refrigeration dryer without loss of compressed air output in the form of purge air. This allows compressed air quality to be adjusted according to the new requirement.

However, if there is a need for a completely new compressed air supply, screw technology is the best solution, economically and technically.

Designed for 24/7 operation, a screw compressor along with proper air treatment equipment is suitable to operate in a laboratory which has a ready-to-use milling machine or has intention to use one in the future.

In a dental facility using a CAD/CAM system, the demand for compressed air enlarges dramatically and the working hours of the compressor increase by 10 to 15 times in comparison to conventional dental labs. This mode of operation is best handled by compressors based on screw technology.

When a new compressor is to be installed, it is also important to consider the compressed air supply of the remaining equipment in the laboratory.

Published in Dental Asia July/August 2021 issue.