Mazak QT15 x-axis noisy sound and vibrations
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    Default Mazak QT15 x-axis noisy sound and vibrations

    Hi,

    I just bought a Mazak QT15 1989 lathe ith T2 control. And I noticed the X-axis sounds like houling when you run it in rapid manualy. I have searched on the internet and found out it could be the bearings. I noticed I have 10-15% load when jogging x-axis even very slow. My first tought was bearings. So I took away the bed cover, and the cover for the the nut adjusting the ballscrew, and I can turn it by hand easly with no backlash and force needed to turn it.

    Is it the servo or encoder? I also read that it might be the coupling that might be loose to the balscrew, I have not checked that yet. But I looked at it before and all screws are still there atleast. The servo is connected direcly to the ballscrew.


    If you hold you're hand on the turret when moving the xaxis you can feel vibrations, like the servo is oscillating and not running smooth as it should. I also read you can tweak the servo parameters, is this possible on the T2?

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    First of all I would lika to say thats I am very happy to see that there is anyone else from Sweden here.
    Were is Sweden do you live? (I live in the Östersund area)

    To your problem:
    10-15% load when jogging X axis is normal.
    Take an indicator and check that every 0,01mm on the wheel is 0,01mm in reallity.
    If you do this over an range of a few mm so the ballscreew turns 1 turn whithout any problem I dont think you have a servo or encoder problem.

    When you do this you can also adjust your backlash with the BL parameters.

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    Hehe, yes im from umeå so quite close to you.

    When I jogg the Z-axis I have no load at all (not even 1%) thats why I tought it might me somthing wrong with x-axis at 10% load when jogging.

    I will try to indicate it with the bed covers gone then I can see the movment of the ballscrew too. I did not get the manual yet, do you happen to know which one if the BL parameter in the parameterlist?

    But still if its noting wrong with the servo, what is causing the vibrations and sound?

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    You have BL X Z C
    X = X-axis
    Z = Z-Axis
    C = C-Axis (T2 dont have the C-axis)

    If your BL X is 20 (0,020mm) and you have a backlash of 0,03mm you set BL X to 50 (0,050mm).
    Then you dont have any backlash anymore.

    I have scanned all my books from my QT10N T2 if you need them.
    Are you familiar with mazatrol T2 already or is this your first Mazak?

    If you dont get any reading on the loadmeter when running Z axxis at 100% I think you have something wrong with that loadmeter.

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    This is my first mazak.

    Yes but is there a parameter that is named BL or somthing so I know its BL. Or do you have the nr for BL kompensation on x and z?

    Another thing I noticed, the jogging is very slow. every "click" is 0.001mm and when I press then x10 button its 0.01mm. Is there a way to scale this to be faster? Really annoying.

    No ideas about the sound from x-axis? If you put you're hand on the turret you can feel the vibrations. And Z-axis is totally smooth and quite. I read some mill had problems with servo gain settings if you had to much backlass it started to "houl/vibrate". My first tough was if its somthing like that.

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    The parameter is named BL

    Press both 0,001 and 0,01 and you get 0,1 per click

    Has it been running all time or has been idling for a time before you bought it? (I guess it has running since it works )
    I have a Mazatrol T3 (T3 is the same as T2 but with C-axis) course documentation in swedish that I think would be great for you, I could scan that for you.

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    As has been mentioned press 1x and 10x together and make sure both the leds stay on and it will give you 100x. The noise may be the ball screw bearings themselves. Especially if you are getting a vibration. Might pay to pull the screw out seeing as you have the covers off already and check all of the bearings

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    Ahh thanks. That makes sense.

    BL x = 12 BL z = 30. (METRIC) And it seems right i have checked with indicator. Can it still be the thrustbearings that makes the sound or should I have more backlash for that?

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    Quote Originally Posted by panscan View Post
    Ahh thanks. That makes sense.

    BL x = 12 BL z = 30. (METRIC) And it seems right i have checked with indicator. Can it still be the thrustbearings that makes the sound or should I have more backlash for that?
    Not neccesarily. They might have swarf in them to give the vibration and the noise

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    Here is a video that shows the diffrence in sound on the axis. Servo noise - YouTube
    I guess T2 is too old to be abel to tweak the servo gains in the parameterlist. I can't find anything about it in the parameters, if its not hidden?

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    It should not sound like that
    Try oil the ballscrew with as much oil as possible to see if the sound change, but I Think you should have a lot of backlash if the sound was from the ballscrew.

    T2 has hidden parameters but most of the machines dont use these. I think they are for options like robot, spare toolmagazine, automatic jaw change, etc.
    You can find the hidden parameters by the following steps:
    1, Enter parameter meny
    2, Press the second or third (Cant remember) yellow button from the right.
    3, enter 1131 and input
    4, Now you have 1 or 2 pages of parameters extra that probably is empty on your machine.

    Would be interesting to remove servo belt and drive the ballscrew by a cordless screwdriver or something to check if noise is from servomotor or the ballscrew.

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    Sqt machines have a hydraylic counterbalance located in the X-axis.If your QT has a similar one, check its hydraylic valve/distributor.It has a pressure gauge,and a regulator.Try to lower the pressure by 5-10%...

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    Quote Originally Posted by benganboll View Post
    It should not sound like that
    Try oil the ballscrew with as much oil as possible to see if the sound change, but I Think you should have a lot of backlash if the sound was from the ballscrew.

    T2 has hidden parameters but most of the machines dont use these. I think they are for options like robot, spare toolmagazine, automatic jaw change, etc.
    You can find the hidden parameters by the following steps:
    1, Enter parameter meny
    2, Press the second or third (Cant remember) yellow button from the right.
    3, enter 1131 and input
    4, Now you have 1 or 2 pages of parameters extra that probably is empty on your machine.

    Would be interesting to remove servo belt and drive the ballscrew by a cordless screwdriver or something to check if noise is from servomotor or the ballscrew.

    But this machine does not have belts to x-axis its a direkt drive, its only a coupling to the ballscrew on the backside.

    Called ravema mazak dealer but they didnt know much he said I should adjust the parameters just by testing. But In the operation manual I can't find any parameters for gain control of the servos. I don't think T2 have that ? I mean my backlash are 0.0012mm on the xaxis. Could it be the ballnut that have moved and is not 100% linear with the rails so its trying to bend the screw alittle and that making the load? I need to point out as you can see in the video this turrent is flat and not at an angle so load should be less than 10-15% when jogging in rapid, or?

    zephyrous:

    This turret have horisontal railes no angle. But thanks for the tip. This is annoying. When I called mazak he said I should have more backlash if it the bearings. But my tought is if this machine have crashed or somthing and that have made diples in the bearing raceways and thats the vibrations? Without loosing any backlash.

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    Default Mazak QT15 x-axis noisy sound and vibrations

    The noisy X sounds mechanical to me ---- probably thrust bearings are bad.

    The ballscrew could be worn, but Mazak's have very good screws, and unless it has been starved for lubrication or wrecked hard, the ballscrew is probably OK.

    Also, the high-quality THK or NSK linear guides are like the ballscrews ---unless they've been starved for lube oil, the guides are probably OK.

    The QT15's are tough, and I would bet the machine will run accurate parts as-is.

    Replacing the thrust bearings isn't too bad of a job, especially on the flat-bed-designed QT15's.


    ToolCat Greg

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    Quote Originally Posted by panscan View Post
    But this machine does not have belts to x-axis its a direkt drive, its only a coupling to the ballscrew on the backside.
    Hmm, my QT10N T2,QT10ATC T3 and ST30ATC T3 has belt from motor to ballscrew and the resolver mounted on the ballscrew via a coupling. (where is resolvers mounted on QT15?)
    I Think it could be worth to remove motor to move X axis "by hand" to see if vibration is still there.

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    Quote Originally Posted by panscan View Post
    Here is a video that shows the diffrence in sound on the axis. Servo noise - YouTube?
    That's your thrust bearings. Its not a screw noise. Go ahead and pull them, you will be surprised how, toxic dirty they look.

    Don't ask me how I know, I just know. Those thrust bearings are toast.

    Regards Phil.

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    Quote Originally Posted by machtool View Post
    That's your thrust bearings. Its not a screw noise. Go ahead and pull them, you will be surprised how, toxic dirty they look.

    Don't ask me how I know, I just know. Those thrust bearings are toast.

    Regards Phil.
    Thanks, I will remove them on sat. and take some pictures. I hope its the bearings, cheaper repair that way . Is there any other way to lock the ballscrew since the nuts are tighten very hard in the coupling to ballscrew. Or is it just to lock it with a screwdriver which is not optimal.

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    Hi again,

    I never "fixed" this noisy problem yet since the machine have been cutting within tolerance no problem. But I feel its time to check the bearings. Anyone removed the servo motor from a QT15 without belt drive? Looks like its a spring coupling between the lead screw and the servo flage. Its all integraded so seem like I have to loosen one bolt and turn the ball screw and then losen next one.

    Next thing is that my x-axis don't home anymore it over travel until the hard stop. So I guess its "only" the switch? And when I bother with this testing to home and checking the switch, I noticed the adjustable stop that runts in contact with the switch was in its longest position so it would home at a very low x stroke. Since I'm struggling to make alittle to big parts for this late would it work to adjust this contact point to optimize the x-axis stroke? I mean I have to rezeroing all the tools if the ballscrew goes another turn or 3 but thats not a problem at all. Right now I have been bothering with special made shortened toolholders, and if it works to move the switch contact point more nearby the hardstop I can use normal holders to do the parts with a hair of margin. I have not been abel to test it yet since it seems like the swish is dead. Can this happen if you turn off the machine outside the home position point?

    Last question, is it possible to see part cycel time? Or estimated cyceltime when doing the simulation? I can't find it. Only part counter and total machine time and total on time etc.

    Thanks in advance!

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    Since none could answer my question, i'll do it my self .

    I have done some testing and it was the limit switch that was broken. No problem found replacement sensors for 28usd. And regarding the travel, its possible to gain more travel just move the limit switch trigger closer to the hard stop, mine was very conservative adjusted I gained almost 45mm more travel in x axis. The limit switch does not have to be as precise as the OEM from mazak which have repeatabillity of 0.05-0.1mm as long as the servo stops at the same rev, and the pitch of the ballscrews are quite high so no problem mouting any microswitch if have to do a quick fix and don't mind make a small mouting bracket for it.

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