We have a Mitsui Seiki HR5B horizontal machine center with fanuc AC spindle motor A06B-1012-B-100, drive A06B-6044-H112 and fanuc 11M control.In the last few months it has been intermittently functional and very sporadic.
All the time though it would stop with error 38 - spindle speed abnormal. At times it would run perfect at 200 rpm but would alarm out at 1000 rpm and sometimes it would do the opposite. At the same time the loadmeter would stay at maximum for a longer period than normal at start up before it alarms out. Turning the control off the loadmeter would stay at around 50% and motor turning a good half a minute unless the maiin switch is turned off.
Having minimal understanding of cnc I would assume though that the parameters must be ok if it function ok at times. One of the encoder cable wire was found frettaged and had only a few strands left so we install a new encoder with new cable with no effect to the problem. By the way the encoder compartment behind the motor was half filled with oiil. The motor was mega tested ok though.
When it is running ok, it would then sometimes make noises different to normal running and coincide with fluctuations of the loadmeter. The odd sound appears to be coming from the motor and at the back of the drive assy behind the pcb.
I would appreciate all the help given to resolve my machine problem.