How do You Select a Rotary Index Table?

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When it comes to the manufacturing of rotary index tables, there are many ways to achieve movement of mass. Whether extremely light inertia loads or loads in the hundreds of thousands of kgm2. Whether it is rotating, lifting or pushing, there are many variables to consider when selecting a robust rotary index solution that will meet or exceed your expectations. Below are two important aspects to consider when choosing an indexer for your next application.

Accuracy

How important is accuracy for your application – This is all relative. To some a ¼” +/- is fantastic and will meet the accuracy for their application. Others need accuracies in the microns for measurement indexing devices for example. Then, there is the applications that fall within those extremes. The misconception is that you can take an inaccurate indexing device and make it accurate by introducing shot pin or wedge lock devices. These devices add complexity and cycle time to use and in the case of introducing these devices with a highly accurate indexing machine can cause damage also making it less accurate. Under real world testing, with choosing specific components, Motion Index Drives, servo rotary indexers have measured accuracies as high as 5-6 microns. These are not results professed by Motion Index Drives, these are results testified by customers.

Backlash

Backlash in the indexing system – When it comes to starting and stopping masses, it is important to know how fast you need to stop your applications mass. In a less rigid environment or where increased backlash is present, the faster starts and stops will pose many problems with control. When moving a mass whether rotary or linear, starting and stopping in a system with several arc minutes of backlash can cause a lot of back and forth motion within the gearing system. The result is a force that can be difficult and maybe even impossible to calculate. Furthermore, when a gear head is used for a rotational application, the further from the center of rotation the mass is, the more backlash is magnified. In applications where the decelerations times are extremely slow the backlash may not be a problem. Think of a ferris wheel at a carnival, it takes several seconds to stop. Now, can you imagine if that ferris wheel is to start and stop in fractions of a second? The vibrations alone would most likely tear the ride apart within days or maybe hours of constant starting and stopping in a fraction of seconds. In the case of cam indexers, there is “Zero Backlash.” The mechanics of a cam indexer offers an extremely rigid, very controlled system. Our cam indexer systems are able to withstand fast cycle times with stop times in the milliseconds. We utilize this same technology in our linear Precision Link Conveyors to give an extremely accurate smooth motion.

Additional things to consider when choosing an indexer will be highlighted in further editions. To learn more about rotary index tables in general, see our guide here.

Interested in learning how to select a rotary index table? Get the guide below!

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