Applied Motion Products—a supplier of high-precision, cost-effective motion control products including stepper and servo motors, drives, controllers, gearheads, and power supplies—says it has developed a system to control heat problems associated with a peristaltic pump system that supplies materials to a bioreactor by replacing open-loop step motors with closed-loop step motors. A peristaltic pump, with internal tubing that separates media from pump components, offers a sanitary method to supply the bioreactor with various fluids to grow cell cultures in the development of new medicines. Step motors are used to drive the pump head, compressing and releasing the pump tubing to move media into the bioreactor chamber.
Typically, excessive heat generated by open-loop step motors elevated the temperature of fluids being pumped into the bioreactor. The higher temperatures, in turn, adversely affected biological processing times and reduced yields. Integrated closed-loop step motors from Applied Motion Products are meant to reduce the heat problem by operating cooler and consuming less power than open-loop step motors.
Incorporating encoder feedback and servo-control firmware, the closed-loop step motor system’s current is meant to be controlled to meet torque demands. Drawing only enough current as needed, the closed-loop step motor should generate less heat than an open-loop step motor. Closed-loop step motors are also designed to run quieter and more smoothly than their open-loop counterparts. Open-loop step motors operate continuously at full current regardless of load requirements, which has resulted in excessive heat generation.
Switching to a closed-loop step motor also enabled the life sciences company to use a single-size NEMA 23 step motor made for addressing all combinations of pump tubing and media instead of stocking different pump and motor sizes. This change to a single motor supported the development of one standard pump head assembly that required only switching tube adapters to dispense different materials to the bioreactor, according to the company.
Amcor also says using an integrated motor design also reduced componentry and decreased space requirements in the control panel. Combining a step motor, encoder, drive, controller, and connectors into a single package, the integrated motor made need for cabling to connect separate motion control components together unnecessary, which freed space in the control panels. Dual-port Ethernet connections were used to enable daisy-chain connections of Ethernet signals among multiple motors to reduce network cables routed around the equipment and back to the control panel.