Many applications using ORCA^TM Series Smart Linear Motors benefit from the ability to have a freely rotating shaft when an additional degree of freedom is required. Made from smooth stainless steel, the shaft ensures the motor is fully waterproof and IP68-rated, while maintaining its robust build. Unlike traditional linear actuators, the shaft can rotate freely, offering several benefits including reduced friction and wear, improved efficiency, increased precision, and design flexibility. For instance, in polishing or grinding tasks, a polishing disk may require a precise amount of force while simultaneously being powered by a separate drive motor. In such scenarios, a freely rotating shaft is ideal for this application.

There are instances where immobilizing the shaft from rotating during operation can be beneficial for your application. Some applications require an “end effector,” where the component attached to the end of the shaft remains stationary during operation. For example, when installing press-fit inserts, the motor is used to apply and monitor a specific amount of force and depth, but it may be undesired for the tooling die at the end to rotate. In such cases, preventing the shaft from rotating can be advantageous for achieving the desired result and ensuring precise control during the process.

This application note will describe various ways you can immobilize the shaft from rotating.

When to Immobilize the Shaft from Rotating

• If rotation alignment is critical for the application.
• If there are provisions and space available to attach the specified mechanism.
• If reduced shaft play is desired. 

How to Immobilize the Shaft from Rotating

Mounting a Linear Bearing

There are several methods to use to stop the shaft from rotating. This example outlines a methodology requiring the least number of custom components. Required components are listed below:

• Flange-mounted linear bearings that fit 50mm spaced M4 screws.
• A rail that fits linear bearings with a satisfactory length for a full motor stroke.
• 4X M4 screws with a satisfactory length for a 5mm thread engagement in the stator.
• 1X M3 (or equivalent) screw to mount the rail to the end effector.
• End effector (or shaft mount) with threads for the rail screw – note that this must be rotationally locked to the shaft.

See the diagram above for this mounting option. The mount design features a through hole for the end of the shaft to allow additional components to be mounted on top of the component.

Practical Application Examples

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Component Recommendations for Sample Designs 

See below the links for the various off-the-shelf components used:

• Horizontal Mount Linear Bearing: View Here
• Guide Rail: View Here
• M4X15 Socket Head Screw: View Here

End Effector Design

Always refer to the Datasheet and CAD models for the most up-to-date information on dimensions of the motors. The following resources are for reference only, and should be confirmed through contacting a sales representative.

Critical Dimensions for Determining Mount Design	Critical Mount Features and Dimensions

The function of the component on the right is to add a properly positioned mounting thread for the rail, while being rotationally locked to the shaft. This can easily be combined into a design of a more comprehensive end-effector that might accomplish more functionality.