Acetal air motor selected for food packaging machine

American packaging machine manufacturer Greydon Inc encountered difficulties when designing a system to bag-up meat and cheese and labelling the packages with appropriate information. The cost of modifying a standard electric motor to suit the machine's intended 100 per cent caustic washdown environment proved cost-prohibitive. Moreover, in such an environment it is best to minimise the use of electronic components.

Greyudon therefore sought a low-cost motor to meet these requirements but with a relatively high degree of precision and control. These qualities were needed by the Greydon Bagaire Taped Bag Loader not only for efficient bag opening and filling, but also for code-dating with inkjet or contact printers.

Brian Newman of Greydon states: "The Huco Dynatork piston air motor was a good find for us. It is compact, fitting in a snug space under the machine. And as the bags are opened with a puff of air from the pneumatic system, an air motor was the ideal solution."

The machine presents the bags by winding up a leader tape and pulling the bags up from the table. Shop air is used via an air amplifier to blow open the bag for manual filling by the operator, who simultaneously breaks the bag away from the tape. The Huco Dynatork motor advances the bags quickly and stops them precisely in exactly the same location for opening and printing. As it is available with an acetal housing, this motor is able to withstand the caustic acids and chlorinated sanitisers used in the food and pharmaceutical industries.

How the air motor works

Air is supplied at up to 100psi to each of three pistons in turn via an integral rotary valve. The free-floating pistons transmit torque on start-up that can be adjusted via a pressure regulator. This results in high torque at variable low speed, and also low noise. As the air motor traps the compressed air within the piston/cylinder, maximum energy conversion is assured. In addition, the motor is said to be much easier to seal than its vane counterpart. As a result, the Huco Dynatork motor consumes up to 80 per cent less air than a vane motor, providing significant cost savings even at maximum torque.

David Lockett, Managing Director of Huco Dynatork, explains that the motor excels in constant start-stop applications under load, displaying similar characteristics to those of a stepper motor: "By comparison, an electric motor will often burn out and a vane motor will stall when subjected to these conditions."

Huco Dynatork air motors are available with maximum torque rating of up to 16Nm or up to 550Nm with a gearbox.