A rotary indexing table moves your payload on a "disc" by pneumatic accelerating. For the later on locking, e.g. to enable the following operation on the workpiece, the retard of kinetic energy also is a valid player in each cycle.
When chosing the rotary indexer, not only "pure load "is the topic, but the position of the load and the location of load compared to the center. The valid pyhsical size is the moment of inertia "J".
Every workpiece inerts turning around a center and inerts every change of angle speed! The moment of inertia depends on the distrubution of mass in relation to the turning center. That means: shape, material (density) and mainly the distance to the rotation axis affect the situation.
Harmful: distance to rotation axis has a quadratic relationship in this formula of physics. In other words: if the mass is near to the center, there is less moment of inertia to handle.
As most often your workpiece is a stated fact, the moment of inertia can be influenced in the construction by
- distance to rotation axis
- design of workpiece-holder
- design of table / disc, the workpiece holder is fixed on
Example 1
Table/disc * partition 4
| kind of disc, material | thickness | diameter | weight | moment of inertia |
| full slice, steel | 10mm | 200 mm | 2,45 kg | 122,5 kgcm² |
| full slice, steel | 10 mm | 250 mm | 3,83 kg | 299,1 kg cm² |
| full slice, steel | 10 mm | 300 mm | 5,51 kg | 620,3 kg cm² |
| full slice, aluminium | 10 mm | 300 mm | 1,91 kg | 214,7 kg cm² |
| full slice, PA6 GF15 | 10 mm | 300 mm | 0,87 kg | 97,8 kg cm² |
| cross, steel | 10 mm | 300 mm, B=25mm | 1,17 kg | 88,4 kgcm² |
Example 2
workpiece, cylinder D = 30mm, length = 100 mm, full material
| material | weight | distance to rot. axis | J cross rot. axis | J along rot. axis |
| steel | 0,55 kg | 0 mm (central) | 4,91 kgcm² | 0,62 kgcm² |
| steel | 0,55 kg | 50 mm | 18,7 kgcm² | 14,4 kg cm² |
| steel | 0,55 kg | 100 mm | 60,1 kgcm² | 55,8 kg cm² |
| steel | 0,55 kg | 200 mm | 225,4 kgcm² | 221,2 kg cm² |
| steel | 0,55 kg | 300 mm | 501,1 kgcm² | 496,8 kg cm² |
A low monet of inertia can maybe be handled by the smaller rotary indexer - less space and less costs!
Link to brochure Rrotary indexing tables - with graphic load diagrams / mass in relation to distance
