I'm working on tracking down a power issue. I'm not sure if the issue is related to the incoming power to a machine, or if the issue is a bad transistor in the Spindle Drive...hoping someone can help steer me in the right direction.

I have 2 Vertical CNC machines with Fanuc 6M controls. Both are wired in a shop from a single rotary 3ph converter. Both machines are essentially the same electronics, motors, drives, and power requirements. However, The spindle on Machine 1 spins up nice and quick at about 80% spindle load during spin up. When machine 2 spins up it pegs the load meter at 200% until it reaches near RPM then tapers back to about 10%. On identical cuts, Machine 1 is at 60% spindle load, while machine 2 is at 125%.

Lately when both machines are running, when machine 1 changes tools, and then spins up, it will cause the spindle on machine 2 to slow a bit and the spindle load meter to be pegged at 200%. Sometimes it can catch RPM back up and be ok, and sometimes it alarms out with AL-02 "Excessive Speed Deviation". My guess is it is either starving for power or giving it all she's got with failing transistors. But I'm not sure if it's low incoming power, or if it is low outgoing power to the motor...

Also I should note that the spindle runs smooth. No electronic noise or chattering is heard. It seems like it is just always low on umph.

Anyone have any hunches or suggestions to try next?

Thanks
Benjamin
Barch Designs
877-201-9771