KRC4 compact cabinet to add a KUKA rotary positioner

I'm not intimately familiar with the KRC4Compact, but having seen the inside of a few, I'm not surprised that KUKA says it doesn't support additional axes.

What degree of motion integration do you need? If you only need an indexer, then you could use a 3rd-party servo and command it using I/O.

OTOH, if you need full kinematic integration, where the robot can weld on the positioner while the positioner rotates, your options are very limited. Either you add a KUKA 7th axis "the right way", or you try rolling your own with RSI (which, while technically possible, would be an entire R&D exercise of its own).

the KRC4compact is the small controller and it powered from a single phase circuit. the same goes for the matching drivebox. obviously this is why there are limitations on current and motor size.

but as usual, when there is a will, there is a way.

small drive and motor can still be used to move huge load. simply change the gearbox to get suitable gear ratio. increasing gear ratio by suitable factor (3 or 10x for example) would give you ability to drive larger loads but speed of the positioner would be of reduced. that may still be ok since arc welding is a pretty slow process and you mentioned using kinematic coupling.

the other option is to not use kinematic coupling. have a larger single axis drive of suitable size (large) and control the positioner as an indexing table. then large drive can make the quick repositioning but there will be no welding on fly while positioner is moving.

technically yes and if i recall it is already made in the form of KRC4 small size 2 cabinet (rather than a separate drive box).