What are rotary actuators and how do they work?
Rotary actuators – also known as rotary drives or rotary cylinders – are mechanical devices designed to convert pneumatic energy into controlled angular motion. Instead of moving in a straight line like linear cylinders, pneumatic rotary actuators turn a shaft through a defined angle – commonly 90°, 180° or up to 360° on selected designs – so you can rotate, index or orient parts in automation equipment.
In pneumatic rotary actuators, compressed air acts on internal mechanisms such as vanes or rack-and-pinion systems. This movement is transformed into smooth and repeatable rotational motion. The result is a compact, reliable and energy-efficient solution for industrial automation tasks requiring precise positioning or indexing.
What types of rotary actuators does SMC offer?
At SMC, we offer a comprehensive range of rotary actuators designed to suit a wide variety of industrial automation needs, from compact tooling to heavier-duty rotation tasks:
Vane-type rotary actuators
Vane-type rotary actuators use internal vanes driven by compressed air to create smooth, repeatable rotation. They are typically compact and lightweight, making them a strong choice when installation space is limited and torque demands are moderate.
Rack-and-pinion rotary actuators
Rack-and-pinion rotary actuators convert the linear motion of air-driven pistons into rotation using toothed racks and a pinion gear on the output shaft.
This design is often selected when you need a robust pneumatic rotary actuator with consistent torque delivery and practical features such as adjustable end positions, with low backlash designs available depending on the series and configuration.
Combination pneumatic units
For compact automation, SMC also offers combination pneumatic units that integrate two functions into one body – such as linear movement with rotation, gripping with rotation or clamping with rotation.
This reduces the number of separate components, keeps piping and wiring simpler and helps speed up machine assembly. Many versions also include easy angle adjustment for common 90°/180° positions and are ready for auto switches to confirm positions, with flexible mounting to suit tight layouts (series-dependent).
Benefits of SMC’s rotary actuators
SMC rotary actuators are designed to make machine design easier by combining compact installation with series-dependent configuration options that help match the actuator to your application and environment:
Space-saving design for easy integration
Engineered with reduced dimensions to save space and simplify integration, SMC rotary drives allow for versatile applications even in tight or restricted environments.
Depending on the series and size, compact designs may also include practical features such as integrated angle adjustment, space-saving auto switch mounting and mounting styles that reduce the overall installation footprint – helping engineers fit a rotary actuator into dense tooling or compact machine frames.
Configurable options for your application and environment
SMC rotary actuators offer extensive options for mounting, rod modifications and environmental adaptability (e.g., spatter-resistant versions).
While options vary according to product family, selected models can offer multiple mounting methods (e.g., direct, flange or foot), along with different output shaft / shaft-end styles, alternative port locations (side or axial) and configurable sensing for position feedback.
Some series also provide application-specific variants or made-to-order specifications – such as different sealing materials, higher temperature versions, corrosion-resistant components or clean-environment options – so you can match the actuator to the installation and operating conditions.
Typical applications for rotary actuators
Rotary actuators are widely used across many industrial automation sectors, including:
- Pick-and-place units
- Indexing tables
- Packaging and labelling machines
- Assembly and handling equipment
Vane-type rotary actuators are often chosen for compact tooling and moderate loads, while rack-and-pinion types are commonly selected for general automation tasks where easy adjustment and stable drive performance are priorities.
How to choose the right rotary actuator?
There are several key factors to consider when selecting rotary actuators for your application:
1. Calculation of the moment of inertia: Calculate the moment of inertia of the part to be rotated with respect to the actuator’s axis of rotation.
2. Required output force: Determine the effective torque required by the application, including: Load weight, inertia and friction forces.
3. Rotating time and angle: Define the required rotating angle.
4. Calculation of kinetic energy: Calculate the kinetic energy of the load and confirm whether the energy is below the allowable range.
5. Confirmation of allowable load: Confirm whether the load applied to the product is within the allowable range.
6. Calculation of air consumption and required air flow capacity: Air consumption and required air flow capacity are calculated when necessary.
Frequently asked questions about rotary actuators
What is the difference between vane-type rotary actuators and rack-and-pinion rotary actuators?
Vane-type rotary actuators use air pressure acting on internal vanes to produce compact rotary motion. Rack-and-pinion rotary actuators use pistons and gears, often chosen when you want stronger torque transfer, adjustable end stops or 360° rotation options (series-dependent).
Do SMC rotary actuators support auto switches for end-position feedback?
Yes. Many SMC rotary actuator series and rotary devices support auto switch mounting to verify end positions.
Can vane-type rotary actuators rotate up to 270°?
Yes. Some compact SMC vane-type rotary actuators are available with 90°, 180° and 270° rotation, and their design allows rotation up to 270° (single vane type).
What’s the benefit of a double-vane-type actuator?
In some vane-type series, the double vane type is standardised for 90° and 100° and designed to provide approximately twice the torque of a single vane type while keeping the outside dimensions similar (series/size dependent).
Are there options for side-ported vs. axial-ported connections on vane-type actuators?
Yes. Some vane-type series offer side-ported or axial-ported versions so you can choose the port location that best matches your piping layout (with certain unit-equipped configurations limited to side porting).
Do rack-and-pinion rotary actuators have different cushioning styles?
Yes. In some rack-and-pinion series, cushioning depends on size/configuration and may be rubber bumper, air cushion or no cushion, helping you match the actuator to the load’s stopping behaviour.
