Synchronised Tapping Attachment
Synchronous tapping features a rigid tapholder rather than one that's flexible, or floating. The floating type also is known as a tension-compression tapholder because it allows axial extension and compression to compensate for some mismatch between the machine's spindle speed and the infeed of the tap.
“With the tapping attachment, you feed in and retract—when you retract it automatically reverses the tap to bring it back out. If you have a workpiece with a lot of the same sized holes, you can have a big impact in reducing cycle time by using a self-reversing tapping attachment.”