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Mazak service

D. Rey

Titanium
Joined
Jan 20, 2003
Location
Phoenix, AZ
So this is like pulling impacted molars here. I've been trying to get a Mazak tech to come out and fix my machine for a month, I can't get them to call me back. Left another voice mail this am, no call back yet. I'm sure they are busy, but I'm ready to get this thing working NOW.


Anyone know a Mazak tech in the Phoenix AZ area I can call?
 
Nah machine is a little beyond warranty, 1986 QT-8 lathe.

It's in great shape besides he alarms, 30,000 on hours, 1400 cut hours on the control. (maybe the whole control was replaced at some point?)

I'm getting axis alarms 12-13 and 25. Manual says that they are following errors, I replaced both resolvers but this did not help. I'm stuck there.


I also need to get a tool setter reinstalled and calibrated.

The biggest issue now is the alarms, I can still run without a tool eye.
 
Nervis1
Did it run a few days ago?
If it did, was it wrecked or crashed? and now it wont run?

Following errors are sometimes the result of a mechanical bind. Are you sure the slides are free and not binding? Manually hand crank the slides from end to end and that should show you a bind if there is one in either the ways, or the screws.
 
Well it will run, I can run through a program and it will sit for a while ~5 min. Then wham, axis freezes and the alarms come up, I restart the machine and all is well for another 3-5 min. I have not had any crashes, who knows about the prior owner.

I can (with the machine off) turn the screws by hand with no problems, smooth has silk.

Dave
 
Well, that sounds good.

I wonder if there is an adjustment on the sensitivity of the alarm.

Kinda like the low oil pressure alarm on a marine diesel that when at low idle RPM, and then put in reverse the idle rpm drops causing oil pressure to fall and that causes the bell to ring, only 2 solutions, raise idle speed or futz with the pressure switch. Maybe there's a futz with adjustment in that control for following error. Back in the really old days, we up'd the gain to reduce following error, who knows what is done now.
 
No. But I will now. I looked and looked for a local Mazak service center, they are not on the radar. Even looked in AZ metalworker.

Thanks for the number.

Dave
 
Discussion with Mitsubishi techs indicate the alarms are overcurrent alarms on the servo drive boards.

One issue was brought up I may have.

Incoming voltage is 250V, the taps on the lathe are 240-260 and the 240 tap was chosen. Would this cause the problem, should I try the 260 tap?

The tech also told me I could use a device to drop the incoming voltage to 240 if I needed to, I would rather not spend the money to do this though unless it was expected to fix the issue.
 
You would be better off to go with the 260 tap, after, check the final voltage input into the drives and see how it compares with the reccomended.
M.
 
Dave,

Some ore numbers for you.

Mazak California: 310 327 7172 they have a service guy that lives in Phoenix. They provide telephone support, but only talk to you if you give them the serial # of your machine.

You already talked to mitsubishi, but their numbers are 714 220 2796 in california and 847 478 2100 in Il. They also do testing of board for a nomnal fee, so you can send a questionable and get it tested instead of slurging for a new one.

Your drive problem may be due to bad brushes in the servo motors, I think they are DC motors, my best memory is that control still used them.

Not to ask dumb questions, but I assume you are going to the diagnose page to see all the alarms, as the position screen only shows one of them.

Good luck on your problems.
 
That's all real useful, thanks for the numbers.

You think the Mazak guy will come out if I call him direct or do you have to go through the regonal repair center?

I did get an appointment BTW, had to play a little phone tag but when I talked to them they sounded pretty nice, helpful.

This machine has AC servos.

The diagnosis page I really don't understand, the alarms are listed on the left and I see 12 or 13 depending if the axis is x or z, then alarm 25, to the right is a big list of on and off abcdefs bits (hex format right?) but I don't have any master list to tell me what all that means.

The Phoenix Mazak man is coming this tuesday, I'll take bets on the problem, (Im guessing DC power supply to the drives as the drive alarm is overcurrent protection) maybe start a pool guessing how much this is going to cost me?
 
too many locked servo rotors on drives
transitor damage
Mitsubishi TRS50b $1500 repair/return apiece
5 to 7 working day's at mits
either that or droop and gain misadjusted
service call 20 minutes work
sorry i didn't see your post sooner
also the thing with the drill offset
if you have the tool index on a t-2 set for home
and then a big negative offset
the machine goes home
then the first thing it does is takes the offset
if there ain't room behind home for this
it smacks the end of the ball screw
and could damage the drive as discused
.
but
that little qt8 is a solid machine when running
i've got about 8 in that vintage that
have been sittin' here for 20 years
making little bolts and the like
for millions of cycle's
and still out perform the
brand new haas light duty crap
 
also
that tool sensor from mazak is about 1700 bucks
go to toolsensor.com
part number h4a-18-50 for about half the price
also
all world mach.
1301 w. diggins
harvard, ill
60033
(815) 943-9111

for many mazak parts
including
tool eyes
switches
seals
and the like
 
also
there is no "calibration" on tool eye
there is a little bar mounted on side
indicate in x-axis to 0--0
then there are parameters to set to get numbers to match machined part
it's easy
i got a book
shot me an e-mail at
[email protected]
i can maybe scan it and mail you a copy
if you look at your parts book
the "referance" numbers are the generic equivalant
on any nonmazak specific parts
 
Nerve
Have you checked for loss motion in your axis? Mechanical slop like wore thrust bearings and bad ballscrews.Since you can power up the machine and it stays on for 5 minutes before it shuts off. It could take that long of the axis hunting for true position and can't find it do to mechanical play either in bearings or ballscrews. Put a .0001 indicator on the end of the ballscrews turn the axis by hand one direction about 1 inch as soon as you reverse directions and your indicator jumps that is lost motion.It should be zero!! There is some adjustment to tighten the thrust bearings. Next you have to determine if its thrust bearings or bad ballscrew. Do the same procedure with indicator on ballnut.

Hope this helps.

Regards
Deckeldoctor
 
I appriciate the advice.

I just did what you asked, the backlash was zero, no play at least on my B+S .0001 guage. When I reverse the direction of rotation by hand no jumping at all, the needle just reverses travel nice and smooth.

I see that the backlash in the control is set to 10 for x (about .004 in?)and 5 (.002 in)for y. The settings are mm/1000 per the parameter page. Should this be zero? When I put my guage on the axis and jog back and forth the backlash also appears zero also. To really check backlash do I have to jog the axis or rapid back and forth to the guage?

Is there anything else that could make the control loose position? I replaced the resolvers about two weeks ago on both axis so that is unlikley to be the source. Never know, maybe I got two more bad resolvers. Now that would be my luck right there LOL.

Dave
 
nerve
The backlash comp would normally be zero. If you had good thrust bearings and ballscrews and the servo drive adjusted correctly. This machine also has ballscrew mapping also in which you can put a compensation factor for every inch of travel. Does this machine have DC drives? Have you checked the servo drive setup lag and drift,since you changed resolvers this could have changed ?

Regards
Deckeldoctor
 








 
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