Which CNC motor to choose? Well, there’s no easy answer to this as every case requires an engineer and/or designer to identify and implement the most practical solution for a particular project’s task, requirements, and budget.
Electrical motors are needed when the application needs precise control, for instance, stepper and servo motors. Both motors are able to perform the exact job, which is rotating the shaft a specific number of turns or degrees, but each one does it differently.
In this blog, we’ll discuss the difference between stepper motors and servo motors for CNC machining so you can determine which is more suitable for your project.
What are Stepper Motors and how do they work?
Stepper motors divide the full rotation in a couple of steps. They use the permanent magnet or an iron rotor to accomplish this and the series of electromagnets that surround it. All these components make up a motor’s stationary part, also called a stator.
Motors activate every electromagnet in a controlled sequence to advance the rotor step by step. However, this kind of division isn’t universal. The motors are also able to attain the sub-step resolution by using the fractional stepping technique. During this technique, the motor activates several phases all at once, and the users are able to achieve greater control when they activate phases in the analog method known as ‘micro-stepping’.
What are Servo Motors, and how do they work?
Just like stepper motors, servo motors range in different sizes, price points, and shapes. Certain inexpensive micro-servos for hobby-use usually feature the variable resistor, allowing them to move to and return from the angular position even with external force.
In addition, there’s also more pricey industrial servos that feature both position and speed feedback. Oftentimes users couple such motors with gearboxes in order to increase their torque. Users can actually command servo motors by using external control hardware for traveling to a specific position and turning in a highly controlled manner.
So what do you need, stepper or servo motors?
It all depends on your requirements. The fundamental difference between the two that you should consider comes down to the following:
- Stepper motors don’t feature feedback. They can’t provide you with feedback on whether or not they have traveled their intended distance. In case there’s a glitch in a system or even physical impediment during spinning, they may skip steps and then continue along like nothing’s wrong.
- Servo motors feature feedback. When servo motors are commanded to get to a specific position, they will do their best just to get there.
- Torque vs. speed. Another important factor worth mentioning is that stepper motors usually lose torque when the speed increases, meaning the servo motor is better for higher speeds. However, steppers exert great torque at low speeds.
- Sensors. In case you are using a stepper, you will most likely be required to have the ability to order the system to “zero” so the known point before a system can accomplish its designated task.
Have any more questions regarding stepper or servo motor? Give us a call. The experts at Epic Tool will be happy to assist you.