mazak VQC 20/40b spindle lube alarm

Hi everyone,
My VQC occasionally stops with spindle lube alarm, switching m/c off and restarting clears alarm. Ive checked the filter in the lube tank under the chiller unit and it was as new - no cleaning required. Return filter in head is spotless, oil is near new and correct type, chiller fins are clean and fan operates as normal.
I disconnected the wire to the oil pressure sensor on the spindle and m/c starts normally and then after time, alarm comes on, which suggests, perhaps fault is in chiller area- any idea,s would be appreciated - cheers

The chiller is for cooling oil, not spindle lube oil. Depending on max. spindle speed, there are various types of lube used. The high speed ones generally use an air oil mist system. The lower speed units with a gear box have another lube pump for the gearbox, and may use grease lubed bearings in the spindle.
The VQC 15-40 I was near today has a chiller, gearbox lube pump , a Way oil pump, and a hydraulic pump.

Switches do go bad, and suction seals on pumps let air in when they get worn (low pressure), and wires going to the spindle area do break on older machines, there are 2 flex loops.

There are quite a few variations over the years on these machines, and it may take awhile to locate the problem.

Occasionally means? once a day? or once a month? Locate the on screen status bit for that switch (pull the wire and watch it change). When it stops, check that bit asap, if it is open, jumper the switch to see if it comes back to a 1. When you power up the machine, there is a period of time before any lube checks are done, and homing the machine may make the problem go away for awhile. There also may be 2 (or more) switches that can cause the same alarm.

Bill

The chiller is for cooling oil, not spindle lube oil

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i think maybe that is for the head stock
the old vqc's are kind of a "gear box spindle lube combo" i believe and if it is a one time grease pack cartridge (which it may well be i've never pulled a vqc spindle) the machine still calls alarms in this system "spindle lube"
i suspect you are right though it's gonna be some little dip sht sensor somewhere.
there is also a little tracoid pump that returns oil from head, if that sight glass on side of head is showing oil its not pumping back correctly. not sure if there is a sensor up there or not
every time i get a new operator they come running over and say the head has no oil cause the sight glass is empty. wrong

every time i get a new operator they come running over and say the head has no oil cause the sight glass is empty. wrong

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At least their looking

Wippin nails it again! The reason it will run for a while is, the alarm is on a delay after the pressure switch drops out. This timer is reset each time you power off/on. Thus it will run until the timer counts out. Had one machine that would not run until I installed a guage snubber under the pressure switch. Two other exact machines ran fine without. Go figure. Put you a tee with a guage installed and watch to see if the pressure is indeed dropping off or if the pressure switch is dropping out while you still have pressure. I forget the threshhold on those sending unit types, but maybe you will have the large adjustable one instead. See attached pages from the maintanence manual.

Vqc - spindle oil pressure

Thanks everyone for reply,s Leelund is right with respect to the fact that my VQC indeed uses the chiller to cool spindle oil, the trochoid pump acts as scavenge pump just like dry sump system in race cars etc. I think installing tee in take off for pressure sensor and fitting pressure gauge is the answer.
After resetting m/c the alarm often will not come on for hours or days, the service manual says that the pressure sensor is activated whenever pressure drops to below 0.3 kg/cm, or .66 psi which is next to nothing, i,m wondering what is normal running pressure is, when hot. i would think it would be at least 30 psi +.After i have installed gauge i will reply with the result, thanks for help cheers