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Maybe off topic but I'm gonna ask...

aj

Hot Rolled
Joined
May 12, 2006
Location
Burlington, North Carolina
Anyone here ever hear of a spindle run-away problem with Takasawa lathes and Fanuc controllers? We had a guy worked here about 3 days that said something about it happening where he worked.
 
Anyone here ever hear of a spindle run-away problem with Takasawa lathes and Fanuc controllers? We had a guy worked here about 3 days that said something about it happening where he worked.

usually fanuc parameter book is not the easiest to understand. if a parameter not set correctly many bad things can happen
 
Depends of whether or not Takisawa used a Fanuc drive for the spindle or something from another manufacturer. Vintage of the machine has a lot to do with that. Prior to the early 80s, Fanuc did not make spindle drives and motors above 20-25HP so builders had to use someone else for bigger machines. The interfacing of errors or alarms between components from different manufacturers varies widely. AC versus DC also makes a difference. A DC field wound motor can easily run away if the field voltage control circuit malfunctions.

In the end the guy's story could be true. As often as not I've seen similar tales be the result of using CSS (G96) and not putting in a G50 S____ to limit the maximum speed to something reasonable for the workpiece and facing in to X0 or canceling tool offset combined with an X0.
 
Depends of whether or not Takisawa used a Fanuc drive for the spindle or something from another manufacturer. Vintage of the machine has a lot to do with that. Prior to the early 80s, Fanuc did not make spindle drives and motors above 20-25HP so builders had to use someone else for bigger machines. The interfacing of errors or alarms between components from different manufacturers varies widely. AC versus DC also makes a difference. A DC field wound motor can easily run away if the field voltage control circuit malfunctions.

In the end the guy's story could be true. As often as not I've seen similar tales be the result of using CSS (G96) and not putting in a G50 S____ to limit the maximum speed to something reasonable for the workpiece and facing in to X0 or canceling tool offset combined with an X0.

you would think a parameter would limit max rpm even if program asks for it. like limits of Feed rate you can program F5000. but most machines will only give max set by parameter. i can see mm and inch and G20 G21 giving a wrong or unexpected feed rate too
 
I understand that a DC motor can runaway if it loses its field coil current (?) while it is running. When I rebuilt a cnc lathe with a 20 or 30 hp motor on it, it had a keep relay in the cabinet in the field coil circuit, so that if the circuit went dead, then the main contactor would open and kill the power to the motor.

More modern drive amplifiers can detect this field loss and shut down the drive, too, in a more controlled manner.
 








 
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