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MPL-B520K-MK72AA Low-Inertia Servo Motor — Detailed Product Introduction, Technical Parameters, Applications, Advantages and Model Recommendations

The MPL-B520K-MK72AA is a high-performance low-inertia brushless AC rotary servo motor belonging to the MP-Series MPL low-inertia servo motor family. It is designed for industrial motion-control systems where accurate positioning, rapid acceleration and deceleration, stable speed control, and repeatable machine movement are important.

This model uses a 460 V AC class, 4000 rpm operating-speed class, 165 mm frame size, 50.8 mm magnetic stack, multi-turn high-resolution absolute feedback, a keyless shaft, and a right-angle SpeedTEC DIN connector. It is supplied without an integral motor brake.

The following information is organized for technical comparison, product selection, engineering reference, and product description purposes. Where a complete overall mechanical envelope is not reliably established from the available model-level information, the dimensional section distinguishes the confirmed frame/stack dimensions from dimensions that should be checked against the mechanical drawing before fabrication.

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1. Product Basic Information

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2. Product Introduction

The MPL-B520K-MK72AA is a low-inertia brushless rotary servo motor intended for applications requiring controlled rotary motion rather than simple constant-speed motor operation.

Its low-inertia design allows the motor to react quickly to changes in the commanded position and speed. This characteristic is particularly useful on machines where the motor repeatedly accelerates, decelerates, reverses direction, or performs short positioning movements.

The motor operates in the 4000 rpm speed class, making it suitable for relatively high-speed machine axes. At the same time, its approximately 10.7 N·m continuous torque provides a useful torque level for medium-duty industrial motion applications.

A major feature of this particular configuration is its multi-turn high-resolution absolute feedback. The feedback system allows the servo system to monitor motor position with high resolution and maintain closed-loop control over repeated machine movements.

Another important characteristic is the keyless shaft. Instead of using a traditional keyed shaft connection, this configuration is intended for compatible clamping, coupling, or other keyless mechanical transmission arrangements. This can be useful when the mechanical design calls for a precise shaft connection without a conventional shaft key.

The model is also configured without an integral brake. This makes it a straightforward choice for horizontal axes and other applications where a motor-mounted holding brake is not required.

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3. Product Series and Model Code

The MPL-B520K-MK72AA belongs to the MP-Series MPL low-inertia brushless servo motor series.

The model number itself provides useful information about the motor configuration.

This coding system is useful when comparing different motors from the same family.

For example, changing the shaft designation from K to a keyed-shaft configuration can produce a motor with substantially similar electrical performance but a different mechanical interface. Similarly, changing the brake designation from 2 to 4 identifies a brake-equipped version.

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4. Detailed Technical Parameters

Important dimensional note: the 165 mm frame size and 50.8 mm magnetic stack length are key dimensional specifications for this model. However, the complete external dimensions—such as total motor length, shaft projection, flange dimensions, mounting-hole spacing, and connector clearance—should not be estimated from the frame size alone. For machine fabrication or replacement work, the applicable mechanical drawing should be used.

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5. Dimensions and Weight

For equipment selection, the frame and magnetic-stack dimensions are particularly important because they determine the general mounting class and motor envelope.

The approximately 11.3 kg motor weight should be considered when designing the mounting plate, machine frame, linear axis, rotary mechanism, or other supporting structure.

For replacement applications, the weight is also important because a replacement motor with a substantially different mass can affect mounting rigidity and machine dynamics.

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6. Main Performance Characteristics

6.1 4000 rpm High-Speed Operation

One of the key characteristics of the B520K configuration is its 4000 rpm speed class.

This makes the motor suitable for applications where the machine needs relatively fast rotary movement, rapid cycle times, or high-speed positioning.

Typical examples include high-speed indexing mechanisms, feeding systems, rotary positioning equipment, packaging equipment, and other automated machinery.

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6.2 Low-Inertia Construction

The motor is designed as a low-inertia servo motor.

Low rotor inertia is valuable when the machine needs frequent speed changes. Instead of being optimized primarily for slow, constant-speed rotation, a servo motor of this type is intended to respond quickly to command changes.

This can improve:

• Acceleration response
• Deceleration response
• Positioning performance
• Reversing response
• Short-cycle operation
• Synchronization between multiple axes
• Dynamic response during machine indexing

For machines with frequent start-stop operation, low inertia can be especially useful.

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6.3 Multi-Turn Absolute Feedback

The multi-turn high-resolution absolute encoder is another important feature.

Unlike a basic motor that simply rotates in response to voltage and current, a servo system continuously monitors motor position through feedback.

Multi-turn feedback is particularly useful where the motor can rotate through multiple revolutions and the control system needs to retain accurate positional information.

This can benefit:

• Rotary indexing
• Screw-driven axes
• Position-controlled conveyors
• Packaging machinery
• Automated assembly
• Pick-and-place mechanisms
• Winding and unwinding systems
• Material positioning equipment

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7. Keyless Shaft Design

The MPL-B520K-MK72AA uses a keyless shaft extension.

This is an important mechanical distinction when comparing it with keyed versions of the same motor family.

A keyless shaft can be suitable for clamping-type couplings and other mechanical transmission designs where the connection is made by frictional clamping rather than a traditional shaft key.

The keyless design can provide advantages in applications where:

• Accurate coupling alignment is important
• A clamping hub is preferred
• A conventional keyway is not required
• Mechanical assembly requires a clean shaft interface
• The transmission manufacturer specifies a keyless connection

However, the shaft connection must always be compatible with the selected coupling, pulley, gearbox, or mechanical transmission component.

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8. No Integral Brake

The MPL-B520K-MK72AA is supplied without an integral motor brake.

This makes it particularly suitable for applications where the load does not need to be mechanically held by a motor-mounted brake.

Typical examples include many horizontal axes, conveyor systems, rotary mechanisms, and other applications where the servo system itself provides the required motion control.

For vertical axes or applications where the load must remain mechanically held after power is removed, a brake-equipped configuration may be more appropriate.

A closely related brake-equipped model is the MPL-B520K-MK74AA.

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9. Connector Configuration

The motor uses a SpeedTEC DIN right-angle connector.

The connector arrangement is designed to make cable routing easier in machine installations where a straight connector would consume excessive space.

The connector is also designed with approximately 180° rotational adjustment, which can be helpful when the motor is mounted in a confined machine enclosure.

This can reduce unnecessary cable bending and make the motor easier to integrate into compact machinery.

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10. Product Applications

The MPL-B520K-MK72AA can be used in a broad range of industrial motion-control applications.

Packaging Machinery

Packaging equipment is one of the typical application areas for high-speed servo motors.

The motor can be considered for:

• Product feeding
• Film feeding
• Indexing
• Cutting mechanisms
• Sealing mechanisms
• Label positioning
• Rotary indexing
• Conveyor synchronization
• Product transfer

The 4000 rpm speed class and low-inertia characteristics can be useful for packaging equipment where cycle time is important.

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Automated Assembly Equipment

Automated assembly machines often require precise positioning rather than simple continuous rotation.

The motor can be used for:

• Component positioning
• Rotary indexing tables
• Assembly slides
• Screw mechanisms
• Pick-and-place systems
• Component insertion
• Automated adjustment mechanisms

The multi-turn absolute feedback is particularly useful where the machine must maintain accurate position during repeated cycles.

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Material Handling Equipment

The motor can also be applied to controlled material-handling mechanisms.

Examples include:

• Position-controlled conveyors
• Transfer mechanisms
• Sorting equipment
• Indexing conveyors
• Automated handling axes
• Belt-driven positioning systems

The exact motor selection should take into account load inertia, acceleration requirements, duty cycle, and transmission ratio.

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Printing and Converting Machinery

Servo motors are commonly used in equipment where several rotating or feeding mechanisms must remain synchronized.

Possible applications include:

• Web feeding
• Roller positioning
• Material indexing
• Cutting
• Tension-control mechanisms
• Registration systems
• Rotary positioning

The low-inertia design can be useful where rapid corrections are required.

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Textile Machinery

The motor can also be considered for textile-related motion systems where accurate speed and position control are required.

Potential uses include:

• Material feeding
• Roller control
• Winding
• Indexing
• Positioning mechanisms
• Synchronized rotary motion

The exact application suitability depends on the required continuous torque, peak torque, speed, and environmental conditions.

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Machine Tools and Automated Machinery

The motor may also be used in automated machinery where controlled rotary movement is required.

Potential applications include:

• Rotary axes
• Feeding mechanisms
• Positioning systems
• Tool-changing mechanisms
• Automated fixtures
• Linear screw drives
• Belt-driven axes

The key consideration is whether the required load profile remains within the motor’s continuous and peak torque capabilities.

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11. Main Product Advantages

11.1 High-Speed Servo Performance

The 4000 rpm speed class provides a good balance between speed and torque for many industrial automation systems.

It is particularly useful when machine productivity depends on rapid movement and short cycle times.

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11.2 Low Dynamic Inertia

The low-inertia rotor design allows the motor to respond quickly to changes in commanded speed and position.

This is useful for machines that frequently accelerate, decelerate, and reverse.

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11.3 Multi-Turn Absolute Feedback

The multi-turn high-resolution encoder provides detailed position information and supports precise closed-loop motion control.

This is an important advantage in applications where accurate positioning must be repeated over many machine cycles.

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11.4 Keyless Shaft

The keyless shaft makes this version different from keyed B520K configurations.

It is suitable for compatible clamping-type mechanical connections and can provide a clean mechanical interface for suitable couplings.

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11.5 Compact 165 mm Frame Class

The 165 mm frame provides a relatively compact mounting format for a motor with approximately 3.5 kW output capability.

This can be advantageous when machine space is limited but a smaller motor does not provide sufficient torque or speed.

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11.6 Flexible Connector Orientation

The right-angle DIN connector and approximately 180° rotational capability can simplify cable routing.

This is especially useful in compact machine designs where cable space behind the motor is restricted.

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11.7 No-Brake Configuration

For applications that do not need a motor-mounted holding brake, the no-brake configuration avoids adding unnecessary brake hardware.

This can also make the motor lighter than the corresponding brake-equipped version.

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12. Five Same-Series or Closely Related Recommended Models

The following models are useful when selecting an alternative within the same B520K/MPL family.

Selection explanation

MPL-B520K-MJ72AA is a close alternative when a keyed shaft is preferred and a brake is not required.

MPL-B520K-MJ74AA is appropriate when the machine needs a keyed shaft and an integrated 24 V DC holding brake.

MPL-B520K-MK74AA is the closest brake-equipped version while retaining the keyless shaft concept.

MPL-B540K-MJ72AA is a better choice when the B520K torque capacity is insufficient. Its torque and power capacity are considerably higher.

MPL-B520K-SJ72AA can be considered when the application calls for a different feedback configuration while remaining within the general B520K mechanical/performance family.

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13. Five Popular Models for Broader Brand Comparison

The following five models provide a broader comparison across the same general servo-motor product range.

These models represent several different application directions.

The MPL-B430P-MJ74AA is useful when a smaller motor and higher-speed operation are more important than the torque level of the B520K.

The MPL-B4530F-MJ74AA and MPL-B4540F-MJ74AA are suitable when a smaller 130 mm-class frame is desirable.

The MPL-B4560F-MJ74AA provides a higher continuous torque level while remaining in the smaller 130 mm frame class.

The MPL-B540K-MJ74AA is the more powerful option when the application requires considerably more torque and power.

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14. Direct Comparison With the MPL-B520K-MJ72AA

The most important difference between the requested model and the keyed B520K version is the shaft arrangement.

Therefore, if the machine already uses a keyless coupling arrangement, the MPL-B520K-MK72AA is the natural choice.

If the existing mechanical system requires a conventional keyed shaft, the MPL-B520K-MJ72AA is the more appropriate alternative.

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15. Comparison With the Brake-Equipped Version

The MPL-B520K-MK74AA is another very close alternative.

For a horizontal axis where no holding brake is required, the MK72AA is generally the simpler configuration.

For a vertical axis or an application where the load needs to be mechanically held after stopping, the brake-equipped version can be more suitable.

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16. Recommended Selection by Application Requirement

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17. Advantages for Industrial Automation

The overall value of the MPL-B520K-MK72AA is not based on one specification alone. Its advantage comes from the combination of 4000 rpm speed, low rotor inertia, multi-turn absolute feedback, approximately 10.7 N·m continuous torque, approximately 23.2 N·m peak torque, and the 165 mm frame class.

For machines that perform frequent positioning movements, this combination can provide a good balance between mechanical size and dynamic performance.

The motor is also relatively flexible mechanically because the keyless shaft can be paired with suitable clamping couplings or other compatible transmission components.

The right-angle connector is another practical advantage in machine construction, particularly where the rear area of the motor is close to guarding, machine panels, or other equipment.

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18. Product Selection Considerations

Although the MPL-B520K-MK72AA has a broad range of potential applications, selecting a servo motor should not be based only on the motor’s rated speed and continuous torque.

The following factors should be evaluated before final selection:

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19. Overall Product Assessment

The MPL-B520K-MK72AA can be regarded as a high-speed, low-inertia industrial servo motor intended for demanding closed-loop motion applications.

Its 4000 rpm speed class makes it appropriate for high-cycle machinery, while the approximately 10.7 N·m continuous torque provides useful continuous mechanical output for medium-duty servo axes.

The approximately 23.2 N·m peak torque provides additional short-duration capability for acceleration, deceleration, and transient loads.

The multi-turn high-resolution absolute encoder is particularly useful for precise positioning and repeated machine movements.

The keyless shaft differentiates this model from keyed versions and should be considered carefully when replacing an existing motor. Mechanical compatibility is just as important as electrical compatibility.

The no-brake configuration is well suited to applications where a holding brake is not required. For applications that require a brake, the MK74AA or MJ74AA configurations are more appropriate alternatives.

The 165 mm frame size and 50.8 mm magnetic stack place this model in a substantial industrial servo-motor class, while the low-inertia design keeps the motor suitable for dynamic motion applications.

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20. Final Product Summary

In practical terms, the MPL-B520K-MK72AA is a strong choice for an industrial machine that needs fast and repeatable servo movement, high-resolution multi-turn feedback, approximately 3.5 kW power, 10.7 N·m continuous torque, 23.2 N·m peak torque, and a keyless mechanical shaft interface.

When choosing between the closely related models, the most important differences are generally the shaft type, brake configuration, feedback configuration, frame size, speed, and torque level. For a direct replacement, the mechanical mounting dimensions, shaft interface, connector arrangement, feedback compatibility, and required drive configuration should all be checked together rather than selecting the motor solely by power rating.