Almost every task in the production/manufacturing such as, the machining, the packaging, the handling, the storing, the sorting and the retrieving etc. and also, the majority of other non-production related tasks in our daily life are characterized by the controlled motion of work pieces, tools, or generally characterized by bringing “things” into motion. To put “things into motion” is dominating all fields of our life. It is one of the most important parts of our activities.
To move masses, inertias, to exert force or torque, to accelerate, decelerate bodies, to overcome friction or keep things in motion was, is, and always will be one of the most vital parts of our life. Today’s automation dominated industry uses a wide variety of devices and equipment to bring “things into motion” (to put things in action, to actuate). These devices are generally called ACTUATORS. There is no established strict definition determining when a device which “moves things” is called an ACTUATOR.
A simple electric motor “the prime mover” can be “just” a motor, or in a specific application become an actuator. The common characteristic of motors drives, actuators etc. is that they convert and condition some form of energy into usable mechanical energy to move bodies (inertias). The output of these devices is force and linear speed or torque and rotational speed. All these devices are compiled of various power transmission components, such as motors with controllers, pumps, gears, couplings, screws, belts, bearings, shafts…. etc. The motors, drives, gearboxes etc. are generally designed and combined into devices to perform a continuous motion. Actuators, on the other hand, are designed to perform a limited stroke, travel or turn. This is one of the fundamental differences and the basic characteristic feature of an actuator. Furthermore, a device called an actuator should include all components required to transform the energy and generate the mechanical energy output. A gearbox, a ball screw, a belt and pulley etc. cannot be considered as an actuator, but they can be vital components of an actuator. On the other hand, an electric motor can perform a continuous running drive function as well as be an actuator performing a fractional turn opening and closing valves if equipped with a suitable control and limit switch set. Based on the above we want to define the ACTUATOR as a device which is converting (transforming) some other form of energy into mechanical motion of defined, controlled limited travel or turn.