Rotary Index Tables have many applications in manufacturing including machining, assembly, inspection and welding. Rotary Index tables are positioning devices used to index parts in angular increments to be machined or assembled. They are application specific and are designed and manufactured to meet the needs of a specific operation or set of operations.

Rotary Index Tables have applications across a wide range of industries. From holding large weldments in aerospace, to positioning containers for label application in consumer goods manufacturing, to positioning medical products components for assembly processes. You can find rotary index tables somewhere in virtually every manufacturing industry. 

Rotary index tables are usually positioned along a vertical axis or can be mounted horizontally. When mounted horizontally there can be a tailstock to support the weight of longer work pieces between to centers.

There are important factors to consider when selecting a rotary index table. In principle, it may seem relatively simple to rotate a component and stop periodically at precise angles. In practice however, it can become a surprisingly difficult challenge to design and build machines that will do this precisely and reliably over the lifespan expected of modern manufacturing machinery.

The number one factor when rotating mass is determining the mass moment of inertia. This is often times overlooked when sizing a rotary device for applications. Once mass moment of inertia is known, a rotary index table can be sized correctly for whatever speed needs to be achieved.

Another important aspect is the size of the piece being moved, how big is it and how heavy is it? Size is an obvious constraint as you need a rotary index table that’s large enough for the piece intended. In order for a rotary index table to operately effectively and not cause internal damage, it needs to accelerate and decelerate at proper speeds.

A third factor is precision. There are some applications such as rotating a large component to allow welding features on it where the individual stop positions can be fairly loose, such as say within +/- ¼” and other applications where repeatable positioning within thousands of an inch is necessary.

When selecting a rotary index table then, it’s important to be able to specify the following:

• - Accuracy
• - Backlash
• - Mass Moment of Inertia
• - Acceleration and Deceleration
• - Speed
• - Environment

To learn more about specifying a rotary table, you can get our guide here.

Servo Driven Gear Head vs. Programmable Index Drives for Horizontal Rotary Index Table Applications

Many rotary index table end users need the flexibility afforded by having a fully programmable tool. A seemingly simple way to achieve this is by using a gear head coupled to a servo motor or an AC motor with an encoder.  In reality though, while this seems simple and cost-effective, because of the physics described above, high inertia, combined with a goal of high accuracy can create a problematic mis-match.

To understand when you should be considering a cam indexer instead, read about the differences here.

Servo Driven Barrel-Cam Rotary Index Table

With a servo-driven barrel cam rotary index table, it’s possible to deliver a wide range of table sizes, with zero backlash and unparalleled accuracy. Servo driven rotary indexers allow heavy inertial loads to be rotated in a very smooth and controlled manner.

You can learn more about this type of rotary index table here.

Cam-Driven Indexing Rotary Index Table

Cam-driven rotary index tables can have significant advantages over other types of rotary index  table drive systems such as gear drives. Cam-driven rotary index tables provide extremely high accuracy because they operate with no backlash. There are several types of commonly used cam-driven rotary index table systems, each is best for a specific application.

Barrel Cam-Driven Rotary Index Table Drive

Barrel cams represent strength in indexing. Primarily found in rotary index tables, indexers utilizing barrel cams feature the greatest strength/size offering available.

To watch a barrel dam in action, see the video here.

Barrel Cam Rotary Index Table Drive

Flat / Disc Cam-Driven Rotary Index Table Drive

Flat, or disc, cams are valuable for their space-saving attributes and the potential to produce very long dwell periods and operate at high speed.

To watch a flat cam drive in action, see the video here.

Flat / Disc Rotary Table Drive

Globoidal Cam-Driven Rotary Index Table Drive

Globoidal cams are similar to barrel cams in shape (and come from the same steel stock), but have considerably different profiles. Tapered walls in the grooves are designed to accommodate cam followers fixed to an output shaft in a "star" configuration.

To watch a globoidal campaign in action, see the video here.

For more specifics on each type of cam-driven automation for rotary index table applications, you can read here.

Fixed and Flexible Rotary Indexing Tables

Cam driven rotary table indexers are sometimes call 'fixed indexers'. With a fixed indexer, the cam drives receive constant power input from the motor. This rotates the cam which then rotates the output. Based upon the design of the drive, the output will have 'dwell' periods (when the output is stopped) as well as acceleration, deceleration and peak velocity. Cam-driven rotary index tables have a number of advantages, however, they won't meet the needs of every application.

Rotary index tables can also be 'flexible'. Flexible rotary index tables use a cam that has a constant lead, that is the output is at a constant velocity if the motor is running at a constant velocity. Constant lead cams provide a high-precision mechanical transition of power to the output and since acceleration and deceleration are still necessary, the logic controller for the index tables motor provides the necessary control.

Rotary Index tables can be configured in a near infinite number of ways to meet the needs of specific applications. 

Common components / accessories that we are asked to provide include:

• Machine Bases
• Slip Rings / Rotary Unions
• Top Dials
• Tooling Frames
• Controls
• Robot Integration
• Custom Coatings
• Motors and Reducers
• Trunnion Riser Weldments
• Mechanical Safety Lockouts
• Explosion proof drive systems

For a more in depth review of these components, you can read here.

Rotary index tables are more and more commonly being integrated with robotics. Robotics provide a next-level of manufacturing capability when using rotary tables. Custom bases are often designed so that the robot can be mounted in the center stationary post of the index drive. With installations like this, end-users can avoid having to relocate or reprogram the robot since they are all one piece. 

To learn more about robot rotary index table integration, please visit here.