[kenny wright]

Mazak FH480, machine will go into low gear, but doesn't read RPM's and will not orient. I've checked the magnet sensor, appears to be in good condition. When you try to orient the spindle, it times out. Any suggestions?

[botha.y]

First of all, has it ever worked before?

[kenny wright]

yes, it was working in low gear before, we sped up the drllls changed velocity and rpms and it quit working.

[Night Shift Wiz]

Have you tried cleaning the two plugs on the magnesensor preamp?

[Rokkin]

If it doesn't read RPMs AND not orient I would say spindle encoder / broken belt.

[Night Shift Wiz]

If it doesn't read RPMs AND not orient I would say spindle encoder / broken belt.

I didn't think mills had spindle encoder belts.

You could also have a gear shift problem. Some spindles only orient in a certain gear. If it won't go into that gear or one of the prox switches is bad it won't orient. Don't think that would affect the rpm display, though.

[kenny wright]

We had the PLG sensor changed one year ago. When we do the manual gear change from high to low it's as if the gears are not engaged, any suggestions on gear shift problem, what would cause it not to stay engaged? Would you start at the back or the front of the spindle? Or is there somewhere else we should look?

[Night Shift Wiz]

We had the PLG sensor changed one year ago. When we do the manual gear change from high to low it's as if the gears are not engaged, any suggestions on gear shift problem, what would cause it not to stay engaged? Would you start at the back or the front of the spindle? Or is there somewhere else we should look?

Gear shifter is usually just a segmented air cylinder (may be hydraulic) (may even be servo motor these days) that pushes the shifter linkage on the back of the spindle. Check for loose hardware on the cylinder or linkage. Could be a chip on one of the prox switches confusing the controller as to what gear it is in. Could be a bad solenoid valve for the cylinder. The controller will usually jog the spindle while shifting gears. If the spindle is unable to jog for any reason that could affect it, too.

[Rokkin]

I'm a little confused. When you say it "doesn't read rpm" are you saying that you're not getting rpm display on the screen, but the spindle turns properly in whatever gear you choose??
From what you wrote initially that is what I was assuming, but based on the subsequent posts that might not be so. If not, please describe the problem a bit more.

Does the spindle rotate properly without any alarms?? Does it start to rotate but sound noisy or does it just sit there and do nothing when commanded??

[kenny wright]

it shifts into gear (visual verification on that) doesnt read the rpms. if you try to manually start the spindle in shows too much load on the load meter and alarms out. if you try to orient the spindle it alarms out on the time. it doesnt make any unusual noise while moving the spindle

[Night Shift Wiz]

Kinda sounds like the PLG again. It will cause erratic motor behavior and overcurrent. There's a procedure for bypassing the PLG and running the spindle motor in open loop. I'm getting ready to leave for the weekend and can't help you with that.