"Motion control, which is necessary for manufacturing industries such as printing, packaging, assembly and semiconductors, is a field of automation and engineering. With motion control systems, machines' positioning and velocity are automated by devices like hydraulic pumps, actuators, or electric motors, such as servo and stepper motor systems. Together, these systems can be used for miniature precision for life sciences to overhead scaffolding for the factory floor.
Motion control systems typically consist of the following components:
• A motion controller to establish markers or set points, and to close loops.
• An actuator such as hydraulic pumps, air cylinders, linear actuators, electric lifting actuators or electric ball screw actuators to carry out the desired motion.
- Servo and stepper motor systems are also actuators. These small motors are found in everyday appliances and electronics such as refrigerators, washing machines or printers. By attaching a servo motor to an electronic actuator, devices can very accurately travel from one side of a system/machine to the other at precise intervals and speeds.
• A drive, also called an amplifier, to transform the control signal from the motion controller into a higher power electrical current that is delivered to the actuator.
• Feedback sensors and related mechanical parts to control the actuator in order to achieve the desired motion. These additional devices include belts, linkages, gears, shafts, ball screws and bearings.
Among the mechanical components most critical to motion control are linear positioners, which are typically either screw-driven linear actuators or electric ball screw actuators. Linear positioning systems are a class of electronic actuators, which come in different housing. They can be screw-driven linear positioners, or belt-driven linear positioners.
Electric ball screw actuators and electric lifting actuators are very similar. They are both used to move parts or devices from one end of a machine to another end. In the case of lifting actuators, the motion is similar to that of an automobile jack. In the industrial arena, these pieces are frequently used in the sorting, unloading and arranging of containers, as well as handling parts to and from the conveyer belt.
When considering such a device for a particular application, most engineers consider the actuator's speed, force, precision and lifetime. And while some companies need high-end repeatabilities from their actuators, other manufacturers look for less costly linear positioners that are not as precise for general automation solutions, when highly accurate and repeatable motions are not as critical.
High quality linear positioners offer maintenance-free positioning and a relatively low cost. When considering industrial-grade, screw-driven linear positioners, manufacturers and engineers should look for:
• Superior bending moment of inertia for high rigidity and minimal deflection
• Lubricated, maintenance-free bearings and rolled ball screws for lower total cost of ownership
• Custom motor mounts for motors (inline and parallel orientations)
"
Chris Muldowney is the president of
Tek-Matic (www.tekmatic.com, Rockford, IL), a supplier and distributor of
automation and control products, specializing in electric ball screw actuators, servo and stepper motor systems and electric lifting actuators
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