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Article | June 5, 2009
Motor delivers big benefits on bagging machine
Electric motors on this bagging machine for manual loading of meat, cheese, or medical devices were not a good fit, so an air motor gets the nod.
A compact, affordable, and easy-to-clean air motor from Huco Dynatork (www.huco.com) delivers precise film advance on the GTBL-1000 Bagaire machine made by Greydon Inc. (www.greydon.com). The Bagaire is a semi-automatic machine used primarily in meat and cheese bagging. Plastic bags—shingled in a box or roll-fed—are joined to each other by a “leader tape” and are fed into the loading station of the machine by advancing the leader tape. The Dynatork air motor is responsible for the advancing. Plant air is used via an air amplifier to blow open the bags for manual filling by the operator, who simultaneously breaks the bag away from the leader tape and sends the bagged product to a vacuum chamber machine or some other form of bag sealer. “It’s a huge step forward in the way bags are presented to the operator for loading product,” says Leo Zitella, sales manager at Greydon. “The air motor is able to advance the bags quickly and stop them precisely in the exact same location for opening and printing.”A key to the selection of the motor was its washdown capability. The Bagaire is designed for the sanitary conditions required in the meat, dairy, and medical industries. It’s constructed mostly of stainless steel and other washdown-approved materials. Because the Dynatork air motor is available with an acetyl housing, it’s able to withstand the most caustic acids and chlorinated sanitizers used in the most extreme washdowns. The operating principle of the Huco Dynatork air motor is simple. Via an integral rotary valve, air up to 100 psi is supplied to each of three pistons in turn. 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 low noise. Because it traps compressed air within the piston cylinder, thus allowing for maximum energy conversion, the unit is said to be easier to seal than a vane motor cylinder. So the Dynatork air motor consumes up to 80% less air than a vane motor, says Huco, providing significant cost savings even at maximum torque.
The motor was recently redesigned with internal air passages that replace the previously external tube structure to further improve its long-life and performance in high-pressure washdowns and other harsh environments where the external tubes might be damaged.
Huco also claims that the motor excels in constant start-stop applications under load, displaying characteristics similar to those of a stepper motor. By comparison, an electric motor will often burn out and a vane motor will stall out when subjected to these conditions.
One other characteristic of the Dynatork air motor that appealed to Zitella was its compact size. “It’s a nice compact unit that fits in a snug space under the machine,” says Zitella. “Bags are opened with a puff of air from the pneumatic system, so to have an air motor was the ideal situation.”
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