Servo Pneumatics Fill Need for Efficiency

A pneumatics company says it has developed a better way to fill plastic bottles and cartons with liquids ranging from orange juice to shampoo.

Hauppauge, NY-based Festo Corp. (www.festo.com) says it is working with makers of volumetric filling equipment to develop servopneumatics-based machines that wouldn't require frequent manual adjustments. If its efforts are successful, Festo says it could eliminate the need for plant personnel to manually turn knobs or screws each time they want to switch to a new liquid or different size container. Instead, they could simply change the machine's settings by touching a screen on a human-machine interface (HMI) located remotely from the machine.

"Any liquid that's dispensed into a consumer package could use this filling technique," notes Scott Schuler, marketing manager for Festo Corp. "And with Ethernet, it could be controlled from any location, anywhere in the plant or in the world."

The new technique would replace conventional methods, which also use pneumatics but are not servo-controlled. Such systems typically operate much like a giant syringe, drawing liquid from a tank by retracting an air cylinder, and then dispensing the liquid into a container by reversing the stroke. The key to making such systems operate accurately, however, is to place a mechanical stop at some point along the cylinder's stroke to keep it from retracting too far.

Engineers at Festo say they want to change the process by replacing the mechanical stop with a servopneumatic system, which would use sensors for feedback and servovalves for position control. The technology, which employs microprocessors to produce forces proportional to the opening in a servovalve, has gained popularity over the past decade because it enables pneumatic actuators to precisely position themselves.

Festo's system includes its SPC200 microprocessor-based controller, an air cylinder with linear position feedback, and the proportional valve. During operation, the SPC200 would typically "talk" with a master controller on the factory floor, which would be pre-programmed with information about the volume of the carton and the viscosity of the liquid. "A company might have three different sizes of orange juice and three different sizes of yogurt, but the controller would 'know,' based on the viscosity and the volume, what position the actuator would need to move to," says Nuzha Yakoob, product management specialist for Festo.

Another Way: Filling plastic bottles and cartons with liquid usually requires frequent manual adjustments. Through servo control, Festo says it can replace the manual adjusting with a system that enables use of a remote touch screen.

The company's engineers, who are talking with several makers of volumetric filling equipment about the technology, claim it eliminates manual labor and does the job more efficiently than conventional methods. "You can get a tremendous amount of consistency with an electronically controlled system," Schuler says. "You're not going to get that same consistency when you've got different people turning a knob or screw to manually adjust the system."

Festo engineers say that the system is also better suited to filling applications than electromechanical means, mainly because pneumatics are considered acceptable in the so-called washdown environments of the food packaging industry.

The company says it can employ the technology on cylinders ranging from 25 to 63 mm in diameter, and on virtually any stroke length. Festo engineers say they are currently working with one European OEM on development of a servopneumatics-based filling system, and are talking with other companies, as well.