About Vacuum
What Is Vacuum? Pressure, Units and Industrial Uses
Vacuum is a condition in which gas pressure is lower than the surrounding atmospheric pressure. It does not require a complete absence of air. In industrial vacuum handling, removing air from a suction cup creates a pressure difference that produces holding force.
Standard atmospheric pressure is 101,325 Pa, or 101.325 kPa (1.01325 bar). Actual atmospheric pressure varies with altitude and weather. Absolute pressure is measured from a perfect vacuum, while gauge pressure is measured relative to the local atmosphere.
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.
Industrial suction cup systems normally operate in the rough vacuum range. A percentage vacuum value describes a pressure reduction relative to a stated atmospheric reference; it is not a scientific vacuum classification. For example, 60% vacuum referenced to 101.325 kPa corresponds to 40.53 kPa absolute pressure. This is rough vacuum, not the high vacuum used in scientific and coating processes.
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
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.
Blower
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).
Ejector
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.
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