Motors: Stepper vs. Hybrid Servo vs. Servo
When shopping for your next laser you will likely read about servo motors and stepper motors. Boss Laser offers different options when it comes to the motors that power our machines. When engineering our machines, we understand the correlation between speed and value. Before deciding which choice is right for you, we must first understand the difference between the motors used in the industry.
WWhat Is a Stepper Motor?
Stepper motors received their name simply because they move in incremental steps between poles. These poles aligned in a circle and are energized individually to turn the motor shaft. In general, most stepper motors in this size range will have anywhere from 50 to 100 poles.
Imagine the face of a clock with a minute hand. And each number is magnetized. When the “1” magnet turns on, the minute hand will shift towards it. Then the “1” turns off and the “2” turns on, thus moving the minute hand towards the “2” on the clock face. This is the same principle being used when a stepper motor operates.
What Is a Servo Motor?
A servo motor operates differently by using less poles, between 4 to 16 in this application, but having the ability to energize multiple poles at once. By energizing multiple poles at once, a servo motor can hold position between two poles, whereas a stepper motor can only hold position on a pole.
To accomplish this, servo motors are also closed-loop. This means they provide feedback using an encoder to the controller about their position. Most stepper motors are open-loop. Meaning they receive a signal to move, but do not send a return signal to the controller about their movement.
What Is a Hybrid Servo Motor?
Hybrid servo motors (also called hybrid stepper motors) are motors that use the high pole count of a stepper motor but feature the closed-loop functionality of a servo motor.
When pushing a traditional stepper motor to the limits, it possible to miss a step. Adding an encoder to stepper motors improves accuracy and allows for stepper motors to be run at higher RPM’s. Higher RPM’s means more speed for your machine without the high cost of servo motors.
Open Loop vs. Closed Loop
Another major difference between these motor types is open loop vs. closed loop. These terms are used to indicate the transfer of information between the controller or driver, and the motor.
In an open loop system, you know where you hope the head will go, but there is no feedback to let you know if it did or how accurately it did so. The signal is sent from the driver to the motor but that is where the transfer of information stops.
With a closed loop system, the motor provides additional feedback to the driver about its position. This is achieved using an encoder. You know precisely where you want the head to go, and you also know precisely where it is.
Stepper motors use open-loop systems. Where hybrid servo and servo motors use closed-loop systems.
Choosing the Right Motor
When it comes to laser machines, faster is always better. The faster a machine can engrave means the more product you will produce. More production is better for business.
For high-speed applications, there is no substitute for servo motors. However, that does come at a cost. Stepper motors are the most economical option, followed by hybrid servo motors.
In conclusion, Boss Laser offers all three options. We know our customers have many unique applications and business aspirations. Our products are designed to meet every need while offering a solution for everyone. If economy is most important, we have stepper motor available. If speed is most important, we have servo motors available. And lastly, if you are in the middle, we have hybrid servo motors in select machines.
|Motor Selection||Max Speed||System Type|
|Stepper Motors||400mm/s||Open Loop System|
|Hybrid Servo Motors||1300mm/s||Closed-Loop System|
|BOSS Turbo Drive Servo Motors||2000mm/s||Closed-Loop System|