What Is The Difference Between Linear And Rotary Actuators?

Actuators are used to move parts in machines. They take electrical or fluid power and turn it into motion. That motion can be either straight or circular. This is where linear actuators and rotary actuators come in. Both are used in many fields, like automation, robotics, and medical systems. They may sound similar, but they work in very different ways. Understanding the difference helps you design better systems and choose the right motion for each task. Let’s start with linear actuators, understand what they are and how they work.

What Is Linear Actuator?

A linear actuator creates motion in a straight line, and we also call this for “linear motion“. It doesn’t rotate. Instead, it moves something forward and back, up and down, or side to side along a path. This motion is created by turning a motor’s spin into linear force. This can be done using a ball screw, belt drive, or other method. Some linear actuators are powered by electricity, others by air (pneumatic) or oil (hydraulic). They are used widely in factory automation systems, hospital beds, and imaging equipment, and so on.

What Is Rotary Actuator?

Unlike linear actuators, rotary actuators move in a circle. They create turning motion, either full rotation or just a few degrees. They’re built to move parts that spin, swing, or turn. A rotary actuator connects to a rotating shaft or arm. When powered, it turns that part smoothly and under control. And they be appliy in robotic joints that move like a wrist or elbow, machine tools that rotate workpieces, and more.

Rotary actuators are important when rotation is part of the task. They are used where full or partial turns must be done quickly, quietly, or with precision. Now that you’ve seen both actuator types, let’s look at how they compare.

The Differences Between Linear And Rotary Actuators

The biggest difference is how they move. A linear actuator moves straight. A rotary actuator turns. But there’s more to it than just direction. Each one performs differently in real-world applications.

Motion Type and Function

Linear actuators are designed for direct push or pull motion. They are used to move loads along a fixed path, such as lifting a platform or sliding a guide rail. Rotary actuators, on the other hand, turn a part around a center axis. This turning motion is ideal for controlling rotation, such as moving a robotic arm joint or opening a valve.

Force And Torque

Linear actuators apply linear force. This is measured in Newtons and describes how much weight they can push or pull. In contrast, rotary actuators apply torque. Torque is a twisting force measured in Newton-meters. In industrial use, torque becomes important in systems like turntables, mixers, or clamping devices.

Space And System Layout

Linear systems often require more installation length. The actuator must extend in the direction it moves. This is a key factor when designing machines with limited space. Rotary actuators are more compact and operate around a fixed axis, making them easier to fit in tight or enclosed assemblies.

Precision And Control

Both types can be controlled accurately, but in different ways. Linear actuators typically use limit switches or linear encoders to manage stroke limits and position. Rotary actuators often use rotary encoders to track angle, direction, and speed. Direct drive rotary motors can reach sub-degree accuracy with smooth control at high speeds.

Energy Use And Efficiency

Rotary actuators, especially direct drive types, are known for their high efficiency due to fewer moving parts. This reduces wear and makes them ideal for clean, maintenance-free environments. Linear actuators, especially screw-driven ones, have more contact surfaces and may need regular service depending on load and travel length.

Applications In Industry

Linear actuators are used in equipment that needs precise lifting, shifting, or pressing. For example, in semiconductor stages, inspection tables, or lab automation. Rotary actuators are chosen when a controlled spin is needed—common in robotic movement, valve operation, or rotary indexing tables.

Both types can also work together in the same system. A robot might use rotary actuators for its joints and linear actuators to move a part up and down.

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