Problem Machine treats feed as rapid after tapping


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    Default Machine treats feed as rapid after tapping

    The Sharp SV-3220 mill with a Fanuc Oi-MC controller that I am using has a malfunction that occurs after a rigid tapping cycle. After the tapping cycle finishes, a tool change takes place, and then the following operations that use G01, G02, and G03 ignore their specified feed rates, and run at what appears to be maximum rapid feed rate! Too fast, obviously to cut parts. Has anyone seen something like this occur, or have an idea why it is happening?

    - The tapping code is below. This machine require M29 to synchronize the spindle and feed rates.
    - There are extra spindle and cooling start/stop commands added before and after tapping just to see that the spindle setting is correct and to ensure cooling while tapping.
    - This machine sometimes has homing and coordinate system problems, especially if a program is stopped prematurely. These problems go away either during the following program, or after a following program runs all the way through once.

    G00 G17 G20 G40 G49 G55 G80 G90
    ...header, followed by tool change...
    M03 S120
    M08
    M05
    G95 G98
    M29 S120
    G84 X.1969 Y.5906 Z-0.44 R0.2 F0.0197
    ...more hole coordinates follow...
    G80 G90
    M03 S300
    M05
    M09

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    Somebody figured out the problem. The machine in this case is in G95 mode, and should be switched back to G94.

    The programming format used in this cycle was spindle speed and pitch--which is feed-per-revolution. This used the command G95, and the feed-per-revolution value is defined by "F." After the cycle is through, the machine is still in G95 mode, so any time a spindle speed is specified for cutting, the feed rate is still calculated for distance per revolution! So that means the machine will try to move extremely quickly for essentially all typical feeds and speeds specified for cutting purposes.

    The solution turns out to be very simple. Once the cycle is finished, G94 needs to be added to put the machine back to feed-per-distance mode. So the line after tapping could look like "G80 G94" plus any other commands that might typically be used.



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    Default Re: Machine treats feed as rapid after tapping

    Interesting, your first line seems quite excessive as to the codes used. Do you need to specify all those codes to your machine?
    I can only say to you I would write it something like this.

    G80G90G54G00 X.1969 Y.5906;
    M8;
    S130 M3;
    M29 S130
    G84 Z-0.44 R.1 Q.076 F10.0;
    M98 P***;
    G0 Z3.0;
    M09;
    M30;

    However many machines are different, from my experience maybe that first line is really confusing the machine. I'm not sure. Haven't ran all machines.
    I would imagine somewhere in the parameters that your machine defaults to G95 instead of G94, maybe watch the boot up. Is this a mill or lathe? The majority of mills will boot up in G94.



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Machine treats feed as rapid after tapping

Machine treats feed as rapid after tapping