Have a Qt-6t with the fusion 640t controller that has had a persistant problem for over a year now. It has a 12 station turret if it matters.

When in automatic mode the turret will sometimes freeze unclamped during a tool change. The spindle is still on, coolant still on. It will not throw an alarm. I have left the machine sit this way for over an hour trying to see if it will stop and give an alarm for diagnostic purposes. The operator has to switch the operating mode (to home, jog, rapid) after which the turret will clamp. Simply resetting the machine does nothing. Then put back in auto and restart the process. When the turret indexes the sound made during clamp is rather pronounced (a loud 'clunking' sound) and there is a 'cavitating' sound made when it is rotating. When standing next to the machine one can actually feel the turret index through the floor. Maybe this is normal, but none of our other 6T's make this much racket during a tool change.

About nine months ago we replaced the turret drive motor at the recommendation of our tech. Someone from mazak in chicago came out and timed it. This issue did not show up again for about three months after that. It doesn't appear to be getting any worse and it doesn't seem to matter which stations are involved. Although it will usually lock up at the same tool on a given program. Sometimes it happens several times an hour, sometimes only once or twice during a shift.

If I'm leaving any crucial information out just let me know and I'll dig it up tomorrow at the shop.

Thanks,

Jason