Fanuc OI-MC Rigid Tapping Issue

VTM · Nov 18, 2021

So this is on a 2008 Fadal 3016FX Per the post title It has a Fanuc OI-MC Control. We've already ran a couple hundred of these parts. Each having three 1/4-20 tapped holes. Swing shift last night all the sudden It starts pulling parts out of the vise while tapping and generally not holding pitch and cobbling up threads. Might tap a couple good holes then go to crap. Unpredictable. Any Ideas here? Is there a way to check that the orientation sensor is functioning properly? Would that even cause the problem? I have two of these machines basically Identical. The only difference I can see is that on the one that is functioning properly. Acts like this right before tapping >> Positions to hole. Spindle orients and stops. Holds position solid until it goes into rigid tap. On the other the same thing except after it orients I can see the spindle rotation drift a bit before going into rigid tap like I said the other is solid, never drifts stays put until it goes into rigid tap.

I know some of you will ask for the code even though we've successfully ran a bunch of parts before this problem. So here It Is. Any help appreciated!

N7G17G80G40G90G49G0
T7M06
( 1/4"-20 CUT TAP )
G90G54
S500M03
G90G0X0.Y.866
G43Z.5H7T1
M08
M29S500
G84G98X0.Y.866Z-.875R.5F25.
X-.75Y-.433
X.75
G0G80Z.5
M09
G91G28Z0.

DouglasJRizzo · Nov 18, 2021

About the only thing I see wrong is engaging rigid tap from a moving (M03)spindle.
Generally, you engage M29 (rigid tap) from a stationary spindle.

VTM · Nov 18, 2021

DouglasJRizzo said:
About the only thing I see wrong is engaging rigid tap from a moving (M03)spindle.
Generally, you engage M29 (rigid tap) from a stationary spindle.

Makes no difference with or without M3. We've tapped 1000's of holes using that same format for years across four different Fanuc controllers successfully.

BobM3 · Nov 19, 2021

No one mistakenly removed the M29 command? I did once. The machine did a pretty good job syncing the vertical and rotation using the just the G84 command. It took a few parts to realize there was a problem.

VTM · Nov 19, 2021

BobM3 said:
No one mistakenly removed the M29 command? I did once. The machine did a pretty good job syncing the vertical and rotation using the just the G84 command. It took a few parts to realize there was a problem.

Nope, The code Is verified good on the control.

Mtndew · Nov 19, 2021

VTM said:
M29S500
G84G98X0.Y.866Z-.875R.5F25.

This part is identical to what I've used forever on a Fanuc control.

I wonder if someone messed with a parameter?

VTM · Nov 19, 2021

Mtndew said:
This part is identical to what I've used forever on a Fanuc control.

I wonder if someone messed with a parameter?

As I mentioned above we have two of these machines that are virtually Identical. I have verified that all the Rigid Tap parameters that I could find are exactly the same between the two machines.

Mtndew · Nov 19, 2021

VTM said:
As I mentioned above we have two of these machines that are virtually Identical. I have verified that all the Rigid Tap parameters that I could find are exactly the same between the two machines.

Maybe an encoder issue?

dandrummerman21 · Nov 19, 2021

Is the belt for the spindle a timing belt (ribbed) or a serpentine belt (smooth like the belt running an alternator in a car) ?

Because we had a mid 90s leadwell with the "high speed spindle" option (was only 10000rpm as opposed to the standard 6000), but to achieve that, they went with a smaller pulley, AND they used a smooth belt instead of a timing belt.

The smooth belt would cause us issues sometimes. If your belt is loose and smooth, I could see that being the issue.

On edit: I would still check the belt situation, but I only now saw you have 2 and they behave differently. I'd be comparing parameters for rigid tapping and see if any of them are different between the two. Looks like they start at parameter 5200. there's a few other parameters for rigid tapping besides those, as i search the pdf for "rigid"

On second edit: You say you've already done that... I gotta start reading it all before typing.

VTM · Nov 19, 2021

Mtndew said:
Maybe an encoder issue?

This is a possibility. Not sure It's easy to test for though and we have no other positioning Issues with the Z-Axis.

VTM · Nov 19, 2021

dandrummerman21 said:
Is the belt for the spindle a timing belt (ribbed) or a serpentine belt (smooth like the belt running an alternator in a car) ?

Because we had a mid 90s leadwell with the "high speed spindle" option (was only 10000rpm as opposed to the standard 6000), but to achieve that, they went with a smaller pulley, AND they used a smooth belt instead of a timing belt.

The smooth belt would cause us issues sometimes. If your belt is loose and smooth, I could see that being the issue.

On edit: I would still check the belt situation, but I only now saw you have 2 and they behave differently. I'd be comparing parameters for rigid tapping and see if any of them are different between the two. Looks like they start at parameter 5200. there's a few other parameters for rigid tapping besides those, as i search the pdf for "rigid"

On second edit: You say you've already done that... I gotta start reading it all before typing.

These are the belts.

.

They could be an Issue although they look pretty good. I've seen much worse. This is one thing we will try first. Incidentally this is one of the differences between the two machines. The one with the problem is a 15k spindle and It has the Hi-Low cylinder setup. But all that looks good upon Inspection. The other is just a 7.5k spindle and only has one timing type belt.

norb · Nov 19, 2021

Maybe run an M19 spindle orient in MDI and see if that helps. I have the same machine.

Vancbiker · Nov 19, 2021

VTM said:
These are the belts.View attachment 334868.

They could be an Issue although they look pretty good. ……

Unless there is an encoder directly driven from the spindle then a slipping belt on reversal is likely the problem.

The Fadal belt changer design is prone to slipping on reverse rotation.

Unless there is an encoder directly connected to the spindle, the system uses the encoder built into the motor. Any slippage in a system like that results in loss of synchronization of the spindle and Z axis.

VTM · Nov 19, 2021

Vancbiker said:
Unless there is an encoder directly driven from the spindle then a slipping belt on reversal is likely the problem.

The Fadal belt changer design is prone to slipping on reverse rotation.

Unless there is an encoder directly connected to the spindle, the system uses the encoder built into the motor. Any slippage in a system like that results in loss of synchronization of the spindle and Z axis.

I agree, we're going to replace them just to be sure. This machine has all Fanuc Red Cap servos Including Spindle motor so no encoder on the top of the motor It Is built in just like you said.

Vancbiker · Nov 19, 2021

If that model Fadal uses that silly air/oil tensioner system you should be sure it does not have air in the oil side.

VTM · Nov 19, 2021

:-) I have two like that. So I'm familiar with the system. That's one thing we've looked at and all seems to be good there.

mmurray70 · Nov 19, 2021

VTM said:
These are the belts.View attachment 334868.

They could be an Issue although they look pretty good. I've seen much worse. This is one thing we will try first. Incidentally this is one of the differences between the two machines. The one with the problem is a 15k spindle and It has the Hi-Low cylinder setup. But all that looks good upon Inspection. The other is just a 7.5k spindle and only has one timing type belt.

Yeah the Fadal high low system with the Hydraulic boosters is a mess. Make sure its working properly as other suggested. This sounds like your problem. Might want to check the orientation sensor too. And the gap between the magnet.

The fadals only have encoder on the motor. There is some belt slip but it reads the orientation sensor every time it passes by and compensates for belt slip. So if you have a bad encoder, belts, tensioners or orientation sensor it could be causing problems.

Are you sure its a 15,000 rpm? I thought the 15000 machines were one speed only with that same belt you pictured. Usually the 2 speed ones are 10,000. Maybe this is something they offered in later years when they had fanuc controls.

VTM · Nov 20, 2021

barbter said:
Check coolant strength....

Yes, check your encoder via M19.

S1000M3
G4P10000
M19

Thin nib black marker pen and make a line from spindle nose across to housing.

Then run up S5000M3
G4P10000
M19
Check line alignment.

S10000M3
G4P10000
M19
Check again etc

I'll try this out and see what we get.

VTM · Nov 20, 2021

mmurray70 said:
Yeah the Fadal high low system with the Hydraulic boosters is a mess. Make sure its working properly as other suggested. This sounds like your problem. Might want to check the orientation sensor too. And the gap between the magnet.

The fadals only have encoder on the motor. There is some belt slip but it reads the orientation sensor every time it passes by and compensates for belt slip. So if you have a bad encoder, belts, tensioners or orientation sensor it could be causing problems.

Are you sure its a 15,000 rpm? I thought the 15000 machines were one speed only with that same belt you pictured. Usually the 2 speed ones are 10,000. Maybe this is something they offered in later years when they had fanuc controls.

The cylinders are working fine. What's the procedure to check the orientation sensor?

This Fadal has a Fanuc spindle motor. So no little plastic round encoder on top like a traditional Fadal Spindle motor.

And yes. It's definitely a 15k spindle.

mmurray70 · Nov 20, 2021

VTM said:
The cylinders are working fine. What's the procedure to check the orientation sensor?

This Fadal has a Fanuc spindle motor. So no little plastic round encoder on top like a traditional Fadal Spindle motor.

And yes. It's definitely a 15k spindle.

Im not too sure to be honest. Cant hurt to do a program telling it to run for while, then orientate, then repeat. Let it run for a while and If thats all good with no alarms or failed orientation its probably fine.

I bet there is still an encoder of some sort in or on the Fanuc motor. Theres obviously an encoder there somewhere or it would be impossible to rigid tap. Shouldnt be too hard to find. Id be tempted to try replacing it. Some newer spindle motors have more complex feedback devices with analog signals that need to be tuned. Never know could be dealing with something like that, I honestly dont know much about the Fanuc Fadals sorry.

Cool! Never saw a 15,000 rpm 2 speed before.

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