For those of you still using a rotary motor with ball or roller screws or belts and pulleys to actuate the moving components on a machine tool, is this still the most efficient method for these applications? I ask because linear motors have not only become more practical for many industry applications in the last decade, but more affordable as well. Linear motors can offer distinct advantages compared with conventional systems such as very high and very low speeds, high acceleration, virtually no maintenance and high accuracy without backlash. Achieving linear motion with a motor that doesn’t require gears, couplings or pulleys is logical for many applications where such components that diminish performance and reduce the life of a machine.
In a rotary motor, the two primary components are the rotor and stator. Linear motors use these same components, except their relative positions are in a line versus a circle. Think of taking a rotary motor and laying it flat. In this configuration, the rotor is attached, with coils of wires, to the moving component, and the stator is a series of permanent or electromagnets located on a non-moving machine component, for example, a base or column. It works the same way as a rotary motor by reversing the polarity between the stator and rotor to produce motion. Linear motors require linear guideways to maintain the position of the rotor in the magnetic field of the stator. Just as rotary servomotors have encoders mounted to them to give positional feedback of the shaft, linear motors require positional feedback from scales mounted along the linear guideway.
To read more about linear motors, the types of linear motors and which is best for your application as well as a link to an in-depth analysis of linear motor principals, visit “Linear Motor Basics."