Electric motors, for the most part, are thought of as independent components. For example, a brushless motor from a typical cordless drill is a self-contained unit, about the size of a lemon, that can be held in your hand. It usually consists of a rotor and a stator, which are assembled into some sort of housing. These are usually bolted into larger machines in order to add rotational motion to the system. For some applications though, the use of a frameless electric motor might be advantageous.
Frameless motors share two major components with their traditional counterparts - the rotor and the stator. As the name implies, a frameless motor omits the housing (a.k.a. the frame) that is present in a traditional electric motor. In a system using a frameless motor, the rotor and stator are mounted directly into the machine assembly.
What Are the Advantages of Frameless Motors?
Though they serve the same purpose as traditional electric motors, frameless motors have some distinct advantages for certain applications.
- Efficiency- Since they are directly integrated into the structure of a machine, frameless motors tend to be very efficient. In a traditional motor, there might be energy loss due to the motor’s bearings or mountings. Frameless motors eliminate the causes of these inefficiencies.
- Stability- Machines using frameless motors are usually more stable and durable than machines using traditional motors. Also, they tend to be balanced slightly better because of the direct integration of motor components.
- Quiet Operation- As a general rule, each additional component in a system is another opportunity for noise. By eliminating some of the components found in traditional motors, frameless motors are almost always quieter.
- Low Maintenance- Similar to the above point, each additional component in a system adds complexity and the need for maintenance. Since frameless motors use comparatively fewer components, they also require much less maintenance than traditional motors.
Where Are Frameless Motors Used?
Frameless motors are typically used anywhere that very high efficiency and low maintenance are required, such as in machine tools, centrifuges, and mixers.
An interesting application is in collaborative robots. Collaborative robots are a subset of robotics that are used to help human operators complete tasks without restrictive safety fencing in place. Instead of traditional motors and gearboxes, frameless motors can be used in the joints of a collaborative robot because of their power and low space requirements. They allow the “limbs” to move naturally while also being unobtrusive to the operator.
Speak with an MCMA member expert about frameless motors and other options for your application.Search for motors experts at MotionControlOnline.org.