Process and production engineers often find the simplest solution to an actuation challenge is the best, with fewer moving parts and reduced complexity usually equating to more reliability with less wear and downtime.
However, even the simplest ideas sometimes have in the past sometimes faced difficulty in achieving market acceptance when they run up against established practice. Like people in many other fields, process engineers and production managers often find it easier to stick with the known.
“Even in those instances where the simpler alternative delivers higher reliability and efficiency at less cost, there has always been an effort involved in changing established ideas and practices. But that could be changing as current economic conditions compel industry to think again to find the best and most cost-competitive methods of production,” says James Maslin, National Sales and Marketing Manager of Air Springs Supply.
Known as Airstroke actuators or Airmount Isolators, these flexible-wall, bellows-type air cylinders are, in essence, tough, fabric reinforced rubber balloons of different shapes engineered to perform different tasks. They can be small enough to fit in the palm of a hand, or more than a metre across and capable of producing 40,000kg of force. They are typically used for high-force, low-stroke applications and for rapid cycle equipment.
“For many applications, including machinery actuation and metalworking, a major advantage of the Airstroke air spring actuators is that they don't use the guides and seals found in traditional pneumatic cylinders.
This difference is the key to many of their benefits in rigorous production environments, ranging from metal stamping and metal fabrication through to mineral processing and conveying applications. Their hygienic performance – they’re easy to wash down and aren’t affected by water or grime – means they are also suited to food, beverage and primary production machinery and high speed labelling, sealing and packaging tasks.”
To acquaint engineers and production managers with the possibilities of Airstroke and Airmount actuators and isolators, Air Springs has developed an extensive website that includes global applications of these technologies, as well as complementary products, such as Pickers and Grippers for manufacturing and packaging plus solid Marsh Mellow isolators.
Traditionally, a fluid power cylinder has had the general geometric shape described above and illustrated at left. In function, however, it's not necessary for an axial force/motion generator to be specifically cylindrical in shape.
Most production and process engineers involved in manufacturing, materials handling and motion control are familiar with the traditional cylinder design. It contains a piston sliding within a housing of circular cross-section connected to the work by a rod passing through one end of the device.
This design necessitates several guides and seals, which align and seal the sliding surfaces. These allow a pressurised, contained column of fluid to apply force to the piston.
An air spring uses none of these components to contain and channel its column of fluid. This difference is the key to its functionality.
An air spring contains its column of air in a fabric-reinforced rubber envelope, or bellows. The ends are sealed by bead plates, which are crimped around the bead of the bellows. These plates contain the attachment hardware for the part, normally a blind tapped hole called a blind nut. An air fitting, generally in one bead plate, allows fluid (air) to be introduced into the Air springs are available in a variety of styles, sporting differing components that control the shape and path of axial extension, but their basic design is the same. Each style is, in essence, a heavy-duty balloon.
In order to select the appropriate air spring, users need to know the force necessary, the linkage motion and any special environmental concerns. A broad range of air springs is available to Australian industry. Airstroke actuators from Air Springs Supply, for example, give 40-40,000kg of pushing or lifting power. Offering power strokes of up to 350mm, Airstrokes are powered by simple, basic compressor equipment found in nearly every factory.
Not only are air springs Airstrokes ideal actuators for many applications, but the structurally identical Airmounts are also a highly efficient isolator. An air spring not only lifts, but also isolates an object. For instance, it can lift and support a vibrating load such as a shaker or vibrator without concern for wear on components. Isolation efficiencies frequently exceed 99 per cent.
As Australian states move toward more stringent workplace and environmental guidelines, this isolation capability is becoming a major factor in machinery design.