The introduction of linear motors changed the engineering scenario in a big way. These electric motors with unique rotor/stator alignment produce linear motion across X or Y axis, unlike other electric motors that offer rotational motion when a magnetic field is created. Today, linear motors are available in low acceleration and high acceleration variants.
Linear motors or axis drive motors are typically used in areas where precision motion control is required. Its rapid positioning capabilities increase productivity levels, lowers maintenance cost and provides multiple stage operation for an array of application areas.
A typical example is a dual axis stepper drive, which offers precision positioning solutions. These motors provides millions of cycles, reduce maintenance due to their direct coupling technology. Its capabilities can be exploited for numerous applications such as; 3D prototyping, material handling and assembly plants, especially electronics and electrical.
As mentioned above axis drives are used in tandem with stepper driver, which are basically brushless DC electric motors. A stepper motor's rotation is divided into four equal parts; which may vary according to the design. These four divisions or electromagnets have teeth on the inner side. When the electro magnets are energized and de-energized one by one by an external control circuit, it moves the rotor in a clockwise direction. The teeth of electro magnets and rotor always remain offset. In this way, every succeeding energized electro magnet moves the rotor by few degrees, providing continuous rotational motion, albeit in steps. The steps required to complete one full rotation depends on the number of rotor teeth.
There are many types of stepper motors, such as permanent and hybrid; each with its own set of advantages.
A torque motor or a direct drive motor is extremely versatile. These motors do not have the housing, bearings and other elements of a native motor. On the contrary, these motors consist of just a rotor, start and a couple. This fourth component which is called the bridge, is used to attach the motor to the machine structure. This bridge also keeps the magnetic field in a restricted enclosure and at the same time, prevents the inner components from damage.
One of the application areas for this motor is a satellite dish assembly.
The absence of gear assembly is compensated by a coupler; which provides the rotational motion.