[onemanshop]

Hi,
I have a Niigata horizontal machine with Fanuc 15, the problem is that the Y axis motor is getting hot after a few hours and stop the machine with SV001 alarm. There is no counterbalance on this machine.

I took all the servos out and cleaned the fins (lots of mud) changed the fans on the power supply and the cabinet.
I changed the servo motor and also switch the servo amplifiers X to Y, but the same problem occurs.

I suspect the problem is the brake not releasing.

How to check if the brake is releasing? Any other suggestions are welcome.

[ifixcnc]

There should be an dc supply voltage to the brake that is switched by a relay. With power off, OHM out the contact side to see if the coil and cable are OK. Then with power on monitor the DC to the coil to see if it is present when the axis is not moving. Also look at the servo page or Moni and watch the load. There maybe something mechanicaly wrong that is running up your load.

[onemanshop]

There is a bridge rectifier S4VB40 before the relay when the main power is on and control off I get 140v DC.
When the control is on the voltage drop to 88v DC and stay the same if I move the axis.
I checked on both sides of the relay (in/out) and get the same 88v. The book shows 100v going into the bridge from the transformer. I believe the brake needs 90v.

Is the brake switching on and off all the time when the axis moves or only when the control is turned on first time?

[ifixcnc]

The brake is only on when the contol is off in this case. This is normal as the axis drive is always on when the control is on. The brake is locking when there is no power. That is a saftey thing, incase of power loss. Did you OHM the brake coil?

[onemanshop]

ifixcnc Thank you for your answers
I checked the brake voltage at the motor and is 89v and looks like the brake works I can hear the click when I switch the control on.

What is weird is that the surfacing program I am running is 90% X and Z moves.

It looks like I need to take a part the Y-axis and look for mechanical problems, bearings, the ball screw or the gibs.
What is the most common mechanical problem you found from your experience?

[ifixcnc]

We have SPN 40s & 50s here, so far no major issues. Knock on wood. Niigata will let you register your SN for 2500$, the tech help is pretty strong. They would not sell us a part untill we registered. So down the road you maybe forced to do so. There are some basic tests one can do to try to isolate your problems. Backlash is a big tell tale sign, or rough movement. Also monitor the load on the Fanuc and see if the bind is local or all thru the travel. Good luck!

[onemanshop]

I tried to find the load monitoring on my fanuc 15 and I can't all it has is a spindle load in the fanuc part that is not showing anything.
What will local bind be caused by?

[ifixcnc]

Bind in a single area is mostly crash related, or alot of wear from alot of use of a certain area of travel. After thinking about this I am wondering if the sensor in the motor is giving you a false reading. Harbor Frieght has cheap Non Contact Infared Temp Guns. Check the motor to see if it really is hot. In the 3100 parameters you can turn on axis load meters. Under the system pages you normaly have the servo tuning pages, load meters are there as well.

[onemanshop]

Thanks again!
Was no crash since I got the machine.
The motor is really hot will burn your hand, I touch it with a wet rag and steam was going up.
I am taking the Y axis off today I hope is just some bearings, there are 4 bearings on bottom and 3 on top.

[Al_The_Man]

I have had this problem on a 15 and it was due to tuning, remove the motor from the shaft or ball screw and power up the machine and see if the motor heats up.
Also while the motor is disconnected check the mechanics.
Al.

[onemanshop]

I tried what you suggested - started the control and the motor was vibrating not rotating and gave me a SV001 after 30 sec.

[Al_The_Man]

I tried what you suggested - started the control and the motor was vibrating not rotating and gave me a SV001 after 30 sec.

Appears to confirm tuning problem, gain too high?
Al.

[underthetire]

Agree, servo tuning sounds off. How are your circles coming out?

[onemanshop]

I took the y axis apart already and planning to change the 4 bottom bearings stack (40TAB09) just to make sure - they don't look too bad.
The ballscrew is smooth and moves on its own weight.

I actually changed the Y servo motor last week and this one is doing the same thing.
How do I adjust the gain? Is there a parameter?

[underthetire]

Ballscrew sounds shot. Should have enough preload to hold its own weight.

[onemanshop]

Ballscrew sounds shot. Should have enough preload to hold its own weight.

Are you sure? The ball screw is big and heavy about 21/4 dia and over 6FT in length.

[underthetire]

Well, are you holding it by the nut or screw? Should be pre load on the ball nut, but if you don't have backlash problems I wouldn't worry to much. Did you check diag for position error while jogging, all three axis should match. If this is a box way machine, you may want to adjust gibs while your in there as well.

[onemanshop]

Th ball screw is in vertical position with the nut mounted on the machine and all bearings out and I can turn it by hand. No backlash before.
The machine is a box way machine - 25" pallets horizontal fanuc 15.

One thing I noticed when changing the servo motor that the spindle head will not glide on its own down.

[underthetire]

Does it have a separate Y brake or is it built in to the motor?

[onemanshop]

Y axis brake is part of the servo motor.

The whole problem with the motor getting hot started when machining 3D surfaces that had thousands of very small moves (.001") in the program.