Pneumatic power is used in industry, where it is common to have factory units plumbed for compressed air although other compressed inert gases can be, and are used in smaller or self-contained systems. It also has applications in, among others, dentistry, construction, and mining industry, just to mention a few.
The use of Air vs. Electrical or Hydraulic cylinders/actuators is application specific, site specific, and a cost specific decision. Additional contributing factors when determining the cylinder/actuator median include issues such as safety, reliability, maintenance schedule, etc. Due to the fact that air cylinders can operate without electricity, there is no chance of spark generation. This makes pneumatic actuators ideal for hazardous environment use, i.e., methane or natural gas applications.
Air cylinders for the most part are simple devices. Furthermore, determining the theoretical force output for an actuator is relatively straightforward. Sizing an air cylinder for a specific application can be challenging. Specifying an undersized cylinder is one of the most common mistakes made when working with air cylinders.
Compare to CENTERLINE and PIVOT mounts, the FOOT mounts isn’t as popular. The FOOT mount is less rigid when compared to the other types of mounts. The plane of the mounting surface is not through the centerline of the air cylinder. However, these mounts are often the perfect solution for unique applications.
Frequently an air cylinder must be able to rotate through a curved path or a PIVOT. The strongest pivot mount is a TRUNNION mount. It compensates for misalignment in one plane by using two robust pivot points. A CLEVIS has one pivot point and may be either fixed or removable and is typically attached to the cap end of the air cylinder.
The best support for a cylinder is along the centerline of the air cylinder. It is called CENTERLINE because the plane of mounting is the centerline of the cylinder.
This is a rigid support that requires accurate alignment.
Centerline mounts may utilize a FLANGE or EXTENDED TIE RODS.
Here are some very important questions regarding the selection of the correct “type” of air cylinder for a specific application:
- What is the required force output?
- What is the required stroke length?
- What is the load?
- How will the cylinder be mounted?
- What media will be used?
- What is the temperature and substance exposure?
Air cylinder functions are literally endless. Here are a couple examples of some common air cylinder applications.
- Opening and closing the gate on a knife gate valve.
- Allowing motion and movement in the animatronics industry.
- Diverting goods on a conveyer system.
- Raising and lowering rides at an amusement park.
- Operating gates to rapidly unload a railcar commodity.
- Press operation in the dry cleaning industry.
- Brush movement in the auto wash industry.
Air cylinders are offered in a variety of shapes, sizes, and types as well as with a multitude of standard options. At first glance, the number of permutations can be a bit overwhelming. The good news is that each cylinder type and configuration has a place in today’s motion-centric automation environment.
Air cylinders are selected by their ability to do work. To ensure maximum production, proper cylinder selection is vital. Cylinder application lives are often predestined long before the product is ever applied. The most common contributing factor that limits productivity is using an undersized cylinder.
Below are a couple of critical cylinder selection practices that should be considered when selecting the perfect air cylinders for the task at hand.
- Determine the force
- Subtract the piston rod area, if applicable
- Know the true operating pressure
- Allowance of internal actuator friction, i.e., seals, bushings, wears bands, etc.
- Know the true load
- Add speed requirements
- Be sure to consider the angles
- Design for slight future productivity requirement additions
- Consider the kinetic energy
These simple steps in the beginning will ensure that your air cylinder will keep your production levels at a pinnacle.