Technology / Frequency AC Motor – Power of Innovations

What You Need to Know About the Frequency AC Motor on SLitter Rewinder

Motors are important components when it comes to the efficiency of any slitter rewinder machine. They are the first parts of a slitter rewinder that will show you if the slitter rewinder is working or not. A motor is the mechanical or electrical device that generates the rotational or linear force used to power a machine.

A slitter machine depends heavily on motors because most of the mechanisms of the machine are rotational. From the unwinding section, slitting to the rewinding sections, all these depend on synchronized rotation to work perfectly. At the center of the rotation are the different motors installed on the slitter rewinder.

Slitter rewinder machines utilize either of these three distinct motors. These include:

  • The AC motors
  • The DC motors
  • Asynchronized servo motors

Slitter Rewinder Motor Types

Motors are mechanical or electro-mechanical devices that convert energy into motion. Energy, in the form of electrical, hydraulic, or pneumatic, is converted to rotational or linear motion and then output to a shaft or other power transmission component where it provides useful work.

As stated earlier, electrical motors utilized in slitter rewinder machines include AC and DC varieties, and the asynchronized servo motor.

The AC motors

AC Motors are electro-mechanical devices powered by alternating current to produce rotational motion. The rotation provides mechanical work to drive other rotating machines such as the unwinding and rewinding shafts of the slitter rewinder machine.

AC motors are highly flexible in many features including speed control and have a much larger installed base compared to DC motors, some of the key advantages are:

  • Low power demand on start
  • Controlled acceleration
  • Adjustable operational speed
  • Controlled starting current
  • Adjustable torque limit
  • Reduced power line disturbances

For AC motors, standard frame sizes are available over a range of powers to ease interchangeability. This means that AC drives make it possible to have motors of different varieties with different enclosure systems. Enclosures can vary from simple open designs to non-ventilated designs that are totally enclosed and fan cooled.

It is worth noting that AC motors form a large portion of motors in use today and drive pumps, fans, compressors, slitter rewinder machines among other uses. AC motors are of different types that include;


In this type of motor, the rotation of the motor is synchronized with the frequency of the supply current and the speed remains constant under varying loads, so is ideal for driving equipment at a constant speed. It is mainly utilized in high precision positioning equipment such as machines and process controls.

Asynchronous motor

Induction motors are also one of the commonly used motors. Induction motors are also known as asynchronous motors because they always run slower than synchronous speed. Induction motors are categorized into squirrel cage motors and slip ring motors.

The DC motors

A DC motor is an electrical machine that converts electrical energy into mechanical energy. In a DC motor, the input electrical energy is the direct current which is transformed into the mechanical rotation.

From the above definition, you can conclude that any electric motor that is operated using direct current or DC is called a DC motor. DC motors have distinct parts that include:

  • The shaft: The shaft extends outside the motor casing allowing connection to an external system to transmit the rotational power.
  • Armature conductors: The armature is a rotating part that rotates on its axis and is separated from the field coil by an air gap.
  • Field winding: A DC motor field coil is a non-moving part on which winding is wound to produce a magnetic field.
  • Pole shoe
  • Frame: The frame protects the internal parts of the motor from water and other environmental elements.
  • Commutator: The primary function of a commutator is to supply electrical current to the armature winding.
  • Interpole: Interpole holdsthe motor shaft in place. The interpole minimizes the shaft’s friction connected to the casing, which increases the motor’s efficiency.

DC motors can be categorized into:

  • Self-Excited DC Motor: In self-excited DC motors, the field winding is connected either in series or parallel to the armature winding.
  • Separately Excited DC Motor: In a separately excited DC motor, the field coils are energized from an external source of DC supply

Because DC motors are varied in their working mechanism, they have different applications depending on the type of the DC motor. For instance, the cumulative compound DC motors are used in rolling mills and elevators while the shunt DC motors are mostly used in smaller machines such as blowers and fans.

It is important that you factor in the type of the DC motor that you want to be installed in your slitter rewinder machine. Consider the component that the DC motor will be running on.

Asynchronized servo motor

Asynchronized servomotors are electro-mechanical devices powered by alternating or direct current to produce rotational motion and positioning. To control the radical position of the motor rotor with respect to its stator, servomotors make use of a feedback loop.

The reason that asynchronized servo motors are widely used is that they are ideal for applications that require motion control. Machines such as the slitter rewinder require smooth, controllable motion to avoid the web from breaking or tearing. Asynchronized servo motors come in handy in such intricate applications.

A good example of the application of the asynchronized servomotors is the guiding of the paper jumbo roll into the slitter head. The slitter rewinder machine utilizes an asynchronized servomotor to index a precise amount or size of jumbo paper roll into the slitter head for slitting.

Asynchronized servo motors have made slitter rewinder automation much easier. Compared with the past, material feeding might have been controlled with a motor driven mechanical indexer which was cumbersome and resulted in poor quality slitted paper rolls.

Differences Between AC Motor, DC Motor, And Asynchronized Servo Motor

There are several differences between the AC motor, DC motor, and the asynchronized servo motor. These differences include:

  • For AC units, the major choice is between induction and synchronous machines. Brake motors are induction machines that have integral brakes which can hold a loaded motor in position.
  • For DC machines, the principal choices are between brushless units and those that employ brushes.
  • AC motors develop higher torque and are brushless while the DC motorshave a lower torque and have brushes.
  • For AC synchronized motors, the rotor winding is fed with a DC supply with the help of slip rings. On the other hand, asynchronized servo motor windings are permanently short-circuited, hence no slip rings are required.
  • If the motor has no commutator and brushes, then it is an AC motor. On the other hand, if the motor has a commutator and brushes, it is a DC motor.
  • AC synchronous motors require an additional DC power source for energizing rotor winding. Asynchronized servo motors do not require any additional power source.
  • AC motors are generally efficient and costlier than asynchronized servo motors,
  • DC motors offer excellent response characteristics when starting, stopping and reversing their spin direction compared to AC motors.

Why AC Motors Are Popular

The AC motors are mostly preferred compared to DC motors. Most of the slitter rewinder machines are installed with AC motors. There are various reasons for this which include;


With only a few moving parts, AC motors have the potential to last for years. The durability of AC motors makes them a preferred solution for heavy use applications such as slitter rewinder machines and other types of machines that require heavy, continuous operations.

High torque

AC motors develop higher torque and are brushless. The speed and the power of an AC motor can be varied using a controller. An AC motor requires no commutator and brushes; hence there is no sparking.


AC motors can work for many hours without overheating. This characteristic makes them ideal for excellent performance in many applications. AC motors are known for excellent performance in many applications without overheating, degeneration or braking. Because they do not overheat easily, AC drives are preferred in applications with high demand of continuous production such as paper sheeting or slitting machines.

Quite operations

AC motors produce less noise compared to DC motors. This makes them ideal for usage in areas that require minimal noise output.


AC motors are available in a wide range of sizes and power outputs. This wide range makes it ideal for many applications.

Best Quality and Efficient Slitter Rewinder Motors

Choosing the right motor for your slitter rewinder machine can sometimes prove to be an uphill task. But at Jota Machinery, we always ensure that we install the best motors in the market in our machines.

For our slitter rewinder machines, we partner with the best AC, DC, and asynchronized servo motor manufacturers. Most of our slitter rewinder machines are installed with Yaskawa AC drives for Siemens master motor.

By partnering with world renown slitter rewinder motor manufacturers and suppliers, we aim at ensuring that you get a slitter rewinder that meets your business needs and that you are guaranteed of quality, efficiency, and durability.

Visit our website to learn more of our broad product portfolio. You can also interact with us on all your inquiries, information, or clarifications on slitter rewinder motors.

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