How to Decide Between Traditional or Integrated Actuators

When machine design engineers are designing linear motion systems, they must consider two types of electric rod-style actuators to ensure that their designs are reliable and efficient.  The two types of actuators available are integrated and non-integrated motor actuators.   Each actuator design offers performance advantages depending on the application type and requirements.

What is the difference between Integrated and Non-integrated actuators?

Tolomatic defines traditional actuators as a screw assembly driven by an external motor that is attached to the actuator by a couple, belt, or gearbox.  Common applications for traditional actuators include sawmill/timber processing; food processing; material handling; pressing/riveting; metalworking and tube bending; and oil and gas applications.  The reason Tolomatic traditional actuators are good solutions for these types of applications is because they offer ease of integration, ability to provide stroke lengths, high force capability and internal anti-rotation solutions.  

Examples of Tolomatic traditional actuators include actuators in the RSX, RSA and ERD series.

Tolomatic defines integrated actuators as a screw assembly rigidly coupled to and driven by an internal hollow-core servo motor.  Security barriers, flight simulators and robotic spot welding are the type of applications that use integrated actuators.  Integrated actuators offer a compact footprint, lighter weight, force repeatability, acceleration and responsiveness, shock and vibration, and ingress protection.

Examples of Tolomatic integrated actuators include the IMA and Servoweld actuators.

Things to Consider when Deciding Between Integrated and Non-Integrated Actuators

1.  Actuator Costs - Traditional actuators typically cost less than integrated actuators.  BUT, when purchasing a traditional actuator, the cost of the servo motor and the labor costs associated with mounting and installing the motor must be considered.  In many cases, integrated actuators are a more economical choice.

2.  Ease of Integration - Because traditional actuators are made up of an actuator, servo motor and motion controller, these items can be source separately, i.e., different manufacturers.

This identifies the major difference because integrated actuators combine the mechanical actuator and servo motor into one unit from the same manufacturer.  This means that the unit must be integrated with the servo drive and motion controller.  Integrated actuators require additional time to configure the integrated actuator to the servo drive and tune the actuator system.

An advantage of integrated actuators is their flexibility to maintain mechanical form, fit and function regardless of the control system being used.  This can provide further flexibility for multiple control schemes while avoiding the need to modify mechanical assemblies.

3.  Size and Weight - The unique compact design of an integrated actuator places the center of gravity along the center axis of the actuator and closer to the mounting face.  The results in more efficient movement when the actuator is used for end-of-arm tooling, especially as the size of the actuator used in the application becomes heavier due to size. 

4.  Platform:  ingress protection, maximum stroke, and anti-rotation - By design, integrated actuators have fewer mechanical joints and fasteners for fewer potential ingress points.  Traditional actuators can have longer travel lengths because the nut assembly travels along the screw, providing support along the entire stroke length.  The design of the nut assembly in traditional actuators combines support with an internal anti-rotate mechanism.  Integrated actuators will typically not be able to accommodate internal anti-rotate provisions while maintaining a high degree of ingress protection.

PRO TIP:  What is ingress protection?  Ingress protection ratings or IP ratings, refer to the level of protection offered by an electrical enclosure, against solids and liquids.  In an environment where dust or water could damage electronic components, a sealed enclosure is used to prevent such ingress and safe house the electronics.

5.  Efficiency and Reliability - Integrated actuators have fewer moving parts than traditional actuators resulting in higher efficiency and reliability.

6.  Positional Accuracy and Repeatability - Integrated actuator's rigid motor connections provide superior positional accuracy and bi-directional repeatability.

7.  Force Capability, Repeatability and Ratings - Traditional actuators provide better performance in high duty cycle and peak performance applications due to more favorable heat dissipation characteristics.

8.  Acceleration and Responsiveness - The rigid connection in an integrated actuator creates a stiff torque transmission system, resulting in increased acceleration rates and responsiveness.

9.  Shock and Vibration - Because of a low center of gravity that is closer to the mounting face, integrated actuators will typically have a higher tolerance to shock and vibration loads.

10.  Safety Considerations for Vertical Loads - Integrated actuators provide a rigid connection between the brake and screw assembly to ensure safe operation in vertical loads.

Additional Resources:

Tolomatic "Your Motor Here" Program