Compact electric rotary actuators provide unlimited 360-degree movement

Festo offers three sizes of ERMB rotary modules, with maximum output torques of 3.1, 8.8 and 24 Nm. The smallest model – the ERMB-20 – measures just 65 x 145 mm with a height of 54 mm and weighs a mere 850 g, making it one of the most compact and lightest units on the market. Yet despite its small form factor, the actuator can handle direct loads of up to 30 kg and moments of inertia as high as 200 kg cm/cm. The largest model, known as the ERMB-32, can accommodate moments of inertia as high as 3,700 kg cm/cm.

ERMB series rotary modules use a pre-tensioned toothed belt to transfer power from the motor shaft to the output pinion, resulting in smooth, low-noise operation with minimal backlash. The actuators’ dynamic performance is little short of spectacular; all three models can achieve an angular velocity in excess of 30 rad/s – which translates into a 180 degree positioning time of less than 0.2 seconds – with a repetition accuracy of ±0.03 degrees.

All ERMB series rotary modules feature a built-in homing sensor for use when indexing, and can also be equipped with an optional sensing kit for monitoring angular displacement. The sensing kit is available with and without a protective housing, to best suit the application, and can be mounted on either side of the rotary module. It uses two sets of easily adjustable cams in conjunction with a pair of magnetic proximity sensors to provide digital feedback to the system controller, and offers a very flexible means of implementing blocking or ‘anti-crash’ motion control sequences.
Festo’s ERMB rotary modules are mechanically compatible with the company’s extensive range of electric and pneumatic products, such as linear positioning axes and grippers, and are suitable for use with a wide range of stepper and servomotors, including third-party products.

When teamed with Festo’s MTR-DCI intelligent servomotors, ERMB rotary modules provide a complete, all-in-one programmable rotary positioning system. These innovative motors incorporate gearing, together with an optical encoder and all necessary controller and power electronics, in a single, compact package, and even offer a built-in LCD option which enables the axis to be commissioned at the point of use, if required. MTR-DCI servomotors can be controlled via a variety of fieldbuses – including CANopen, Profibus DP and DeviceNet – and the built-in controller is capable of storing 16 motion control programs in non-volatile memory, including acceleration and velocity profiles for rotational movement.

Customers can specify a rotary actuator, mounting interfaces and motor/drive combination in a single part number, to help reduce administration time and cost.