Problem with machine and program zero for tool movements

[merhas06]

Hello,

I’m new in CNC and I have a lathe machine ECOCA equipped with FANUC 0i-TC and rear turret.

After the machine setup (reference return position, tool offset, program zero…) and when I want to execute the program all tool movements are referenced to the zero machine and not to program zero[/B][/COLOR]. If for example I want to execute the bloc N10 G00 X100.0 Y100.0, the tools starts the movement to the right and the over travel alarm appear in the screen.

I find this problem at the beginning of the program and in the tool change position inside the program.

With many other programs this works very well and all tool movements are referenced to the program zero at the right end of the part.

I tried many alternatives to fix the problem, but this happens involuntarily and I can’t locate the problem and how to correct it.

Why this happens with some programs and not with others?

You are all kinds to help me.

[neilw20]

Do you have a manual?

[merhas06]

Hello Neil20m

Yes I have the machine manuals.

[neilw20]

Please read the manual as it is specific to your machine.
There should be some examples, and how to define where your work zero is.
Ask more questions, as you become familiar.

[merhas06]

Hello again,

Thanks a lot.
You are perfectly right. I have read the manuals and I have executed many parts on the machine. But sometimes this problem appears with no explication.
What is surprising is that with the same program, at the beginning the tool moves to the wrong direction. After some manipulations like referencing zero return again or pressing reset key,… and it works. I know that these manipulations are nonsense, but sometimes they look good.
I think the G-code is Ok since the graphic simulation is correct.
The FANUC System That I have is FANUC 0i-TC.
The tool offsets are adjusted very carefully and I think they are Ok since it works well with relative coordinates.

[christinandavid]

If for example I want to execute the bloc N10 G00 X100.0 Y100.0, the tools starts the movement to the right and the over travel alarm appear in the screen.

Try re-iterating the current work-offset in use on this line also. This may not apply to lathes, but on mills absolute mode (G90) should also be re-iterated after program restart.

DP

[neilw20]

Use absolute mode.
You will go nuts with incremental mode.
The zero will appear to keep moving. Every point you get to is a new zero. Little wonder you are confused!!!
Incremental mode does have many uses, but learn to work in absolute mode, and understand how it works, before using incremental mode.

[merhas06]

Please have a look on the program and tell me what wrong with this. the program is long, so I omitted the part related to grooving drilling.
The simulation is perfect either on machine or on CIMCAD software.

O0000
N1 G21 G40 G99;
N2 T0100;
N3 G97 S1500 M04;
N4 G00 G42 X55.0 Z0 T0101 M08 (here, the tool moves to zero machine and not to the part??)
N5 G01 X-0.5 F0.2
N5 G01 Z1.0;
N6 X52.0;
N7 G71 U2.0 R0.5
N8G71 P11 Q20 U0.4 W0.2 F0.2
N10 G00 X14.0
N11 G01 X15.0 Z0 F0.2
N12 X20.0 Z-2.5
N13 Z-6.0
N14 G02 X20.0 Z-14 R5
N15 G01 Z-22.0
N16 G01 X20 Z-23.79
N17 G02 X30.17 Z-32.5 R10
N18 G01 X40.0 R5.0
N19 Z-70.0
N20 U2.0 W1.0
N21 G00 X100.0 Z100.0 T0100 M09 (here, the tool moves to zero machine and not to the part)
N22 M01
N23 T0200
N24 G97 S1500 M04
N25 T0202
N25 G00 G42 X55.0 Z1.0
N26 G70 P10 Q20
N27 G00 X100.0 Z100.0 T0200 M09 (here, the tool moves to zero machine and not to the part)
N28 M01
N29 ..
.GROOVE CUTTING
.
N35 ..
. (DRILLING)
.
M30
%

[HuFlungDung]

In your program, I do not see any reference to a work offset (such as G54) or a coordinate system shift (G50). If your controller is an older vintage, it may not use G54 and you will have to set a program datum reference using a G50 X.xxx Z.zzz style command.

Does your manual not address this part of machine operation?

If X100. Z100. is your tool change position, that is not machine zero, since machine zero would be -100 in both axis from that position. The handiest place to have machine zero is X0 on the centerline and Z0 at the face of the chuck. But, there are various ways of handling the machine coordinate system and shifting the work coordinate system upon that system.

First, we'd need to find out what the controller uses. G53 is the machine coordinate system. So look through your manual for sections on G50, G53, G54 and see what comes up.