[kudos]

Hi there,

on our citizen L16 machine i am trying to use the spindle index function to mill some flats,
control is Mitsubishi , Spindle drives are Mitsubishi Z200
every now and then the control will come up with a Spindle index alarm, and i am unsure why as there is no other error to indicate why and manual is not too helpfull also. so i was wondering if any one here has had the same kind of issue and fixed it?

if it was a alarm that always came up im sure it would be more easy to fix, but sometimes we can make a part or 4/5etc then some it will just alarm out, some times index the first position fine, and alarm on the 180 command, other times on the first index (spindle 0)

i may also add alot of the time the pin does fire in and go home, then the control alarms out, only been a few times where it has alarmed out before firing the pin into place, even then it looks to be lined up well to do so,

does the spindle drive it self need a re-tune or something?

here is part of the program if it helps,

M05
M28 S0
M58 S3=3000 G98
G04 U1.0
G00 X11. Z100.5 Y11. T16
X7.
G01 Y-11. F150
M28 S180
G04 U0.5
Y11.
G00 X11. M60
M05
G99

thanks for any help, Rob

[MCImes]

Your code seems fine and because its intermittent, its not a code issue. That would alarm every time in the same spot.

The only times I've seen something similar to this it has been the Main Spindle encoder starting to die. One time this happened to me where the spindle would work fine until you tried to do a synchronized move like tapping or threading, then it would alarm with some spindle alarm. Another case it would not index, tap or thread, but the spindle would work fine for simple turning or drilling.

So my guess is that the encoder on the Main is dying. If its an older machine (which it appears to be based on the code you provided) it's likely that the encoder is starting to go. If you can double check that somehow, try that (you could swap it with another working machine if you have another L16). Otherwise if its not too expensive it'd be worth just replacing the encoder to eliminate that possibility. Thats what it sounds like to me.

Report back with the cause if you fix the problem

[kudos]

HI, thanks for the reply,

i am putting a thread on the shaft, and threading is working just fine never errors and pitch is good so is the finish on threads.
i know it has had a new Main spindle drive at some point in its life going over the paperwork, and also new encoder pully and belts as they lay in a box.
i am not so sure on the encoder side of things.

when i took the encoder cover off, i did notice the encoder was quite loose on the belt , when i sorted that out it did index abit better, i guess as there was alot less slack in the feedback loop. but what your saying does make sense, its a easy overlooked thing too.

i did check the switch feedback on the PLC input bit page and works fine reading the switch

[MCImes]

Hm...if you can get to that screen when its in the alarm state it would be interesting to see if the PLC is reading the bit when its alarmed.

Otherwise a loose belt could sure cause that alarm. Machines dont have much tolerance for slop in the feedback system (for good reason!) before they alarm. If tightening the belt fixed it Id say you found the problem.