125 afc overload alarm

The machine is a 1997 Mazak H400 with an Mazatrol M-2 control. The part is a fairly simple 4 face forging with not a lot of machining. There is one face that gets a 3 sided chamfer that is giving me issues. I had it programmed as a line left in mazatrol, ran almost 1000 parts successfully before I had to shut the machine down and repair a loose Z axis ballscrew support bearing. While in the mess I also repaired a weak encoder coupling on the Y axis. No the rest of the program runs, but I stops at the chamferring unit with 125 AFC overload. SFM is 250, feed is 0.020 per rev, and cutter is a 0.500 cabide end mill with a 0.125 corner chamfer.
I tried changing it to a "manual program" inside of mazatrol with the same result. It comes in to depth, cuts one leg, but stops at the point it would make the first turn of the horseshoe.
any ideas? what in the world does AFC stand for and how does it get overloaded?

automatic focus control (AFC) allows for consistent and repeatable tool load, calculates the cutting load threshold and prevents overload conditions.

There is a code to turn this on/off as well as a setting in cutting conditions I think.

I had the same thing not long ago on the same machine with a 640.

After you replaced the bearings it increased the load on that axis and then when the tool loads it exceed the setting.

Good Luck

AFC in Mazak Lingo is Adaptive Feed Control. You must have the Mazak monitoring option on that machine. Its part of Tool failure, Tool life, Spare tool replacement stuff.

Not sure how you overcome it, as its more a programming issue. Its not an overload in the true sense, as in thermal over load. Tweaking up your encoder coupling might have it following correctly. So things like lag, in-position window, might be causing your hang up, on change of direction. Theres bound to be settings, parameters to do with this adaptive feed control. Never played with them my self. Nuts and bolts guy.

Regards Phil.

You may have to take some of the thrust off that leadscrew or if its ok just change the setting.

If your load monitor is within reason changing the setting is the way to go.

Regards

LOL, I meant Adaptive Feed Control in any case its a simple fix

D.M.

I was just about to barrel you about that one. Focus Control, you see that on the Mazak Lasers.

I’m not convinced on the Z axis drag. He changed two things. The Z axis bearings, and the Y axis encoder coupling. From my read of his description, The Z axis should all ready be at depth, and in position. He’s then interpolating then in X / Y

Hence my suspicion that by tightening up the Y axis feed back loop, my toss of the coin would be on the Y. Because it’s more responsive. I’m guessing that it faults when he has run into the corner, and the tool is cutting more.

It maybe, that the additional, torque on the Y axis due to the new bearings has tripped him into that zone where it exceeds the limits he has in the AFC settings.

How does one, back off the thrust in that axis anyway? Both ends of the screw will carry high contact angle, angular contact, ballscrew support bearings. You have no option other than to positively lock the two inner rings together on the shaft to apply the preload. Short of re-positioning the housing’s, to modify the tension on the screw, not much you can do, is there?

Cheers Phil.

thanks guys
that was driving me nuts
dug through all my books and nuthing had that "125"
in it.
but numbers in that area were not servo load kinda stuff but programing errors
i'm for hack the control if meters look ok

I will look up the setting in the morning.
When I have a machine in front of me.

Regards

The z axis had a loose ballscrew that we fixed and the y axis encoder coupling was all messed up....and all we did was fix the encoder coupling and a little brake work. but what I don't get is that this is a glass scale machine... so WTF, the scale is not used? I don't think I will ever be convinced that mazatrol does not totally suck in mills. having alarms that don't appear in the book, whats up with that? Don't mind me, just a Fanuc guy venting.......any help is appreciated.

After I thought about it , the AFC alarm is generated by the spindle load not axis.

It was in my alarm manual, thats why I fixed it in 2 minutes and didnt really expore it further.

Get back to you tomorrow with more information.

Best

I looked in the "Tool File" on a 640T it had about 6-7 field's that has to do with AFC.

Look there and you will find the issue with AFC

Hope this Helped

Regards

what fields in the tool file has to do with AFC? This is a 1987 Mazatrol Cam M-2, so many of the things present on the 640 may not be present here. I won't get a chance to look it over until second shift today...