About Vacuum
What is Vacuum?
Taken literally, vacuum in physics describes the absence of material. However, a space that is completely free of materials has not yet been found in the entire universe. In common speech, the word “vacuum” is used for a space that is virtually free of air. If the remaining pressure is only slightly lower than the atmospheric pressure, the correct term is not “vacuum” but “underpressure”. It is also important to remember that the ambient air pressure around us is dependent on the weather and altitude.
A typical value that is frequently specified for this is the standard atmospheric pressure of 101.325 pa (approx. 1 bar), which corresponds to a mass per unit area of around 1 kg/cm2. This pressure is caused by the air masses in the atmosphere: the higher you are, the lower the air column above you and therefore the lower the air pressure. Because everything around us is ultimately exposed to this air pressure, it is generally not perceived as such.
Attempting on Vacuum
The first attempts to provide evidence of vacuums were carried out by Otto von Guericke. An air pump was used to remove the air from two hemispheres (“Magdeburg hemispheres“). 16 horses were then used to attempt to pull the spheres apart. However, the ambient air pressure pushed them together so strongly that it was impossible to separate them. This principle is also used to lift and hold elements using a vacuum. You are also exploiting the fact that the ambient pressure joins the workpiece that is to be lifted to the suction plate relatively firmly.
In the vacuum handling technology sector, we operate exclusively in under-pressure areas, which are designated as low vacuums in technical literature (<99%). A higher vacuum would simply be uneconomical for handling tasks and would be disproportionate to the higher holding power. When classifying, you talk of low vacuum below 60% and high vacuum from 60% onwards.
How to create vacuum
In the industrial field, industrial suction cups are powered by vacuum. The most important vacuum generators are as follows:
Vacuum pump to generate differential pressure in a sealed space (similar to a compressor). This generates a relatively high final vacuum (max. 99.9%). There are various designs. Dry-running and circular oil lubricated rotary vane pumps, claw pumps, liquid ring and screw pumps. Rotary vane pumps and claw pumps are the most reliable pumps in handling technology.
The side channel blower/compressor generates a differential pressure in which large quantities of air can be moved (similar to a vacuum cleaner). The underpressure that is generated is in the lower range (max. -450 mbar). There are single-stage and double-stage compressors. The difference is the underpressure that can be achieved (single-stage up to a maximum of -250 mbar, double-stage up to a maximum of -450 mbar).
According to Wikipedia, an ejector is a jet pump that generates under-pressure and that therefore has a predominantly sucking effect. This is widely used in vacuum technology. Ejectors are commonly used in the packaging industry. They are cheap to manufacture and acquire. They are relatively expensive to operate due to their high compressed air consumption.