Linear Actuator | FAQs

1. Determine the force required to move the load:
   • Force: Mass of the load × Acceleration
2. Calculate the weight of the load:
   • Weight: Mass × Acceleration
3. Determine the acceleration and deceleration:
   • Acceleration: (Final Velocity – Initial Velocity) / Time
4. Calculate the total load:
   • Total Load: Force + Weight

Yes, linear actuators can both push and pull. When extending, they apply a pushing force, and when retracting, they generate a pulling force.

Key factors to consider for pulling applications:

• Load Capacity: Ensure the actuator can handle the required pulling force.
• Mounting: Proper installation is crucial for effective force application.
• Durability: Choose actuators made from robust materials to withstand repeated use.
• Examples:
  • Automotive Seats: Actuators pull seats back to their original position.
  • Door Systems: Actuators pull doors open and closed smoothly.

Modifying the stroke size after manufacturing is hazardous and can potentially damage the unit. For example, adjusting the stroke length of a hydraulic press once it's assembled can compromise its structural integrity, leading to mechanical failures or safety risks. Similarly, altering the stroke dimensions of an engine component post-production may result in improper functionality and reduced lifespan of the machinery.

Much of the noise from a linear actuator is caused by vibrations in its housing. As the electric motor operates, it induces vibrations throughout the actuator’s body. When these vibrations contact hard surfaces, they produce significant noise.

The duty cycle is expressed as a percentage and represents the proportion of time a linear actuator is actively operating versus resting. For example, a 50% duty cycle means the actuator runs half the time and rests the other half. Understanding the duty cycle helps ensure the actuator is used within its operational limits for optimal performance and longevity.

No, a linear actuator does not inherently apply a constant force. To maintain steady force, sophisticated control systems with feedback mechanisms are required.

• Examples:
  • Closed-Loop Control: Uses sensors to adjust the actuator’s force based on feedback.
  • Open-Loop Control: Lacks feedback, so force can vary depending on conditions.
  • Feedback Systems: Essential for applications requiring precise force control.

A linear actuator is classified as a second-order system because it combines mechanical components (mass, springs, and dampers) and electrical elements (inductors, capacitors, and resistors), leading to complex behaviors like oscillations and resonance.

• Manual Control:
  • On/off switches: Used to extend or retract the actuator.
  • Wireless remotes: Enable remote operation for convenience.
• Electronic Control:
  • PLCs or microcontrollers: Provide automated control for precise operation.
  • Sensors: Offer feedback for real-time position monitoring and control.

• Limit Switches: These are physical switches placed at the actuator’s endpoints. When the actuator reaches an endpoint, the switch is triggered, signaling it to stop.
• Position Sensors: Devices like encoders monitor the actuator’s exact position and send signals to stop when the desired position is reached.
• Built-in Controllers: Some actuators have integrated electronics that automatically stop movement based on pre-set positions without external sensors.

The stroke length of a linear actuator refers to the total distance the actuator's output shaft can extend or retract from its fully retracted position to its fully extended position. Essentially, it defines how far the actuator can move in a single operation.

What is a Servo Motor:

A servo motor is a specialized rotary actuator designed for precise control of angular or linear position, velocity, and acceleration. Unlike standard motors, servo motors incorporate built-in feedback mechanisms—such as encoders or potentiometers—that continuously monitor the motor’s output. This feedback allows for real-time adjustments, ensuring accurate and repeatable movements essential for high-precision applications.

A servo-based linear actuator is a highly precise device that converts rotational motion from a servo motor into controlled linear movement. Unlike standard linear actuators, servo-based models incorporate advanced feedback mechanisms, such as encoders or potentiometers, which continuously monitor the actuator’s position, velocity, and force. This real-time feedback allows for precise adjustments, ensuring accurate and repeatable motion control.

Key Features:

• Precision Control: Achieves exact positioning with minimal deviation, essential for applications requiring high accuracy.
• Integrated Feedback Systems: Utilizes sensors to provide continuous monitoring and adjustment, enhancing reliability and performance.
• Dynamic Performance: Capable of rapid and responsive movements, suitable for applications demanding quick and exact actions.

Advantages:

• Enhanced Accuracy and Repeatability: Critical for maintaining high standards in precision-dependent environments.
• Improved Control: Advanced feedback systems enable fine-tuned adjustments, reducing errors and increasing operational efficiency.
• Versatility: Suitable for a wide range of industrial applications, from heavy machinery to intricate automation systems.

Motor Options

V_max = (Motor RPM × Lead (mm/rev) ÷ Gear Ratio) ÷ 60

• V_max: Maximum linear speed in millimeters per second (mm/s).
• Motor RPM: Rotational speed of the motor.
• Lead: Distance moved per revolution of the screw.
• Gear Ratio: Accounts for reduction or increase in speed due to gearing.
• 60: Converts minutes to seconds.

• Connect power terminals: Ensure the voltage matches the actuator’s requirements.
• Link control inputs: Connect inputs (like extend and retract) to a controller (e.g., PLC or Arduino).
• Attach sensors or limit switches: Monitor the actuator’s position for accurate control.

Typically, a standard rotary motor is employed, converting rotational motion into linear movement using various mechanisms.

• Rack-and-Pinion Setup: Ideal for applications requiring high speed but lower strength, such as automotive steering systems.
• Worm Drive: Used for slow movement with high mechanical strength, common in heavy machinery and conveyor systems.
• Perpendicular Axis Configuration: Motor axis is at a right angle to the direction of motion, seen in robotics for compact designs.
• Screw Drive with Gearbox: Provides moderate speed and high strength, commonly used in CNC machines and 3D printers.

The PLA is offered with the choice of three types of screws…a ball screw, lead screw and acme screw. These are offered in various select screw leads per the sell sheet.

Yes. Sudden external forces that occur while a system is stationary or moving require a larger safety factor then steady loads. Such loads can be generated by inertia due to impact and vibration or starting and stopping. The following table contains ranges of safety factors to consider for such loads. To use the safety factors, multiply the nominal load magnitude by the appropriate safety factor to estimate the effective load. The effective load should then be compared to the rated load capacity of the actuator.