Rotary indexing tables come in different kinds, but we will be analyzing the wormgear rotary indexing table versus the face gear rotary indexing table.
Wormgear Type Rotary Indexing Table
This kind of table gives you infinite positioning and enables you to carry out rotary cutting. A CNC controlled servomotor rotates a wormscrew. The spindle of the rotary indexing table has a wormwheel that is rotated by a wormscrew. These rotary systems accuracy when it comes to absolute positioning depends on the wormgear set quality. It also depends on the servosystem’s accuracy & resolution as well as the servoposition feedback medium. Lots of servosystems make use of encoders for motor position monitoring instead of using the rotary spindle. To ensure that there are no inaccuracies whatsoever, high-end systems utilize glass scales, or they may make use of encoders exactly on the spindle for monitoring spindle position.
A lot of shops make use of Wormgear Type Rotary Indexing Table due to the fact that it is equipped with infinite positioning and is very flexible when it comes to handling virtually any job that might surface.
If the CNC of the machine tool controls it directly, it is basically called the full fourth axis because it offers the benefits which come with making use of just one CNC program. The operator does not need to carry out any programming at the shop. There’s also a very minimal chance that crashes will result from errors in operation. There is also the capability of making different kinds of movements simultaneously with respect to carrying out helical milling operation which exotic workpieces usually require.
Position accuracy is often an issue because of the lack of industry standards. There are manufacturers that carry out testing and certification with respect to absolute position accuracy in terms of degrees, but they usually fail to tell you what the meaning of their specifications are. Apart from those expensive systems where the rotary spindle comes with directly placed glass scales, accuracy specification mostly applies to a new rotary indexing table prior to crashes subjection which is kind of rare. Wormgear sets can be damaged by very small crashes.
Face Gear Rotary Indexers
Discrete positioning is what you get with these indexers. Minimum index increments will take place at fifteen, five, or one degree, and this is influenced by how many teeth you find on this gear. Regardless of what the minimum increment is, the workpieces which can be machined happen to be those that come with angles which represent minimum multiples.
Face gears which you finding indexes have a similarity with those which can mostly be seen in CNC lathe’s turrets. Indexing must be very accurate and rigid in order to adequately withstand the forces encounter by the lathe turret due to high cutting.
If the face gear indexer is of good quality, there will be a fantastic accuracy in terms of absolute position. This accuracy is maintained as long as the indexer is still in use regardless of how many crashes take place. Units that have the right, absolute position accuracy, which is about 5 arc secs or below can be accessed. They are very ideal when it comes to carrying out very high precision jobs. Rigidity is also very high.
Indexing can only be carried out in increments of five degrees, fifteen degrees, or the minimum specified for the model. The only way that face gear rotary systems (two pieces) can be combined with tailstocks or tombstones which have outboard support is if that support comes with a sliding joint.
You’ll also find face gear rotary systems which make use of a servodrive for the achievement of approximate positioning. Then they go ahead to get their final accurate positioning by depending solely on that same face gear. These systems can move in two directions and very fast. A simple command can be used to program random moves. A pneumatic piston is mostly used by some other systems for approximate position rotation. Systems like that are known to be just one directional. These systems approach to crashes.