Automation Element (Actuator-Pneumatic)

Actuators

1. Pneumatic Actuator

Pneumatic
–        using compressed air: operated by compressed air in a tool or machine
–        physics involving compressed gases: relating to, operated by, or typical of the pressure of compressed gases, especially air pressure or compressed air

Pneumatic is competing with two other working media
    • Electrics
    • Hydraulics

Pneumatic components can perform the following types of motion:
    • Linear
    • Swivel
    • Rotary

Some industrial applications employing pneumatic are:
  • General methods of material handling:
    • Clamping
    • Shifting
    • Positioning
    • Orienting
    • Branching of material flow
  • General applications:
    • Packing
    • Locking
    • Driving of axes door of chute control
    • Transfer of materials
    • Turning and inverting of parts
    • Sorting of parts
    • Stacking of components
    • Stamping and embossing of components.

Energy Supply- Compressed air generation


Compressed air is generated by compressors


Compressor Types

 Description one by one about main compressor types.

1. Diaphragm Compressor.

technical definition simply means that a diaphragm compressor is an air compressor the uses the flexing of a rubber or silicone membrane to compress the air rather than a piston system. Conventional air compressors make use of a piston and crankshaft arrangement very similar to those found in a car engine to compress the air.




Diaphragm Pump Animation



Piston Compressor
2. Screw Compressor.
A positive displacement compressor consisting of one male and one female rotor which contain lobes that when meshed together reduce the amount of available space for the refrigerant gas to occupy, thus compressing it. The male rotor is usually the drive rotor.
             
                      
                             Screw Compressor working 3D animation       

Air distribution

In order to ensure reliable and trouble-free air distribution, a number of points must be observed. This includes primarily the correct sizing of the pipe system, but also the pipe material, flow resistance, pipe layout and maintenance.  
For the production of compressed air, compressors are required to compress the air to the desired working pressure. Then, it supplied by a central line to various drives and components. The compressor and the distributing system can be arranged as follows to achieve a proper air supply.  


Pipe types
·         Steel
·         Glued Plastic
·         Stainless Steel
·         Aluminum



Tube Types

•         Polyurethane tubing
•         Nylon tubing
•         Polyethylene tubing
•         Braided PVC hose
•         Self-fastening hose
•         Recoil tubing
•         Anti-spark tubing


Why compressed air preparation? 
  • The maximum water content of air (100% relative humidity) is highly dependent on temperature. Air can only absorb a certain quantity of water per volumetric unit (in m3), irrespective of pressure. The warmer the air, the more water it can absorb. Excessive humidity manifests itself as condensation. If the air temperature drops from 20 0C to 3 0C, the maximum water content of compressed air is reduced from 18 g/ m3 to 6 g/m3. The compressed air can now no longer absorb more than aprox. 1/3 of water, i.e. the relative air humidity is tripled. If the level of air humidity is to remain the same, the excess 12 g/ m3 must be removed from the air. 


    Class
    Solids
    Water Content
    Oil content
    Max. Particle size(mm)
    Max.Particle Density(mg/m3)
    density
    (mg/ m3)
    Max. dew point (0C)
    Max. oil density
    (mg/m3)
    1
    0.1
    0.1
    0.003
    -70
    0.01
    2
    1
    1
    0.12
    -40
    0.1
    3
    5
    5
    0.88
    -20
    1
    4
    15
    8
    6
    +3
    5
    5
    40
    10
    7.8
    +7
    25
    6
    -
    -
    9.4
    +10
    -
    7
    -
    -
    -
    -
    -


    Water condensation



    Water is always preventing in air in the form of natural air humidity. During the cooling of compressed air, water is released in large quantities. Drying helps to prevent corrosion damage in compressed air system and in the connected consuming devices.

    Oil contamination
    Similarly. In the case of oil-free operating compressors, oil aerosols present in the drawn-in air also lead to a corresponding residue of oil pollutants. However, this oil is not suitable for the lubrication of drives and can even lead to the clogging of sensitive parts.

    Dirt and rust particles
    Solid particles occur in the form of dust (carbon black, corrosion particles) primarily in agglomeration points.
    Coastal regions, in general, have lower level of dust, but instead contain additional salt particles resulting from evaporated seawater droplets. Dust is classified into categories of particle size, i.e. coarse dust (>10 micron), fine dust (1 to 10 micron) and atomised dust (< 1 micron).

    How clean compressed air should be?
    The answer is quite simple: compressed air must be so clean that it cannot cause any malfunctions or damage. Contamination accelerates wear on sliding surfaces and seal elements. This can affect the function and service life of pneumatic components. As each filter also creates a flow resistance, compressed air should be as clean as possible for economic reasons.

    Function of service unit
    The individual functions of compressed air preparation, i.e. filtering, regulating and lubricating, can be fulfilled by individual components. These functions have often been combined into one unit, i.e. the service unit. Service unit are connected upstream of all pneumatic systems.
    Generally, the use of a lubricator is not necessary in advanced systems. This is to be used for specific requirements only, primarily in the power section of a system. Compressed air in a control section should not be lubricated.

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