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IndustryArena Forum > MetalWorking Machines > Sharp CNC > Machine hang during tool change
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  1. #1
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    Machine hang during tool change

    I am hoping someone here can help me with a problem I am having with my Sharp 2412 mill with FANUC Oi-Mate controller. There is no rhyme or reason to this problem and no pattern that I can find. Here is what happens. During normal program exec, the machine will hang during tool change. The TxM6 is called, the spindle goes to tool change height and orients then....nothing. Just sits there with the green light blinking and the control displays M6. I can push the RESET button, switch to EDIT and go back up a few lines to the new tool and start the program from there. It might work normally for a few tools, or hang on the next change. Sometimes, it will run totally normally. Pushing the CYCLE START button during the hang does nothing. I have made sure that M01 is not active on the panel. The problem seems to be getting worse. I am not afraid to dig into the guts and check whatever I need to. Anyone have any ideas?

  2. #2
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    I have a very similiar problem, as yet unresolved.

    Lets say I am running on 25% rapid, and have a tool change in the program. The machine will change tools, then take off at 100% rapid. It will execute the program until the next toolchange, but will hang up on m6 in the toolchange macro exactly as you describe. If it takes off with the wrong rapid rate, it hangs up EVERY single time.

    I personally think it has something to do with being cold. I know that sounds crazy, but the only time mine does it is when it is fall or winter, and I didnt run the heat at night. Start machine up, it hangs up for about an hour then quits, and runs fine. I think is a bad connection somewhere, and when the control doesnt get both signals (in the ladder) it defaults to 100% rapid but cant tool cahnge because of the missing signal.

    You said yours is getting worse, is it getting colder in your shop?

    My dealer has looked at it twice, he added some more dwell time to the toolchange, might have helped some. It went several months without doing it, then 2 weeks ago, started again. I cant get my dealer to return any phone calls. I have an independant repairman coming Monday, if we figure it out I will definitly let you know.

  3. #3
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    Mine used to hang randomly on tool changes (about 1 in 50) and more so when the machine was cold. I would hit the start button and it would continue like nothing was wrong. I turned up the the low side on my compressor so supply pressure would not fall below 100psi and adjusted the regulator on the back of the machine to the high side of the green zone. Knock on wood, it seems to have fixed it. Also, check your supply lines to make sure you are not restricting it through funky plumbing.

  4. #4
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    Spock, you have described the EXACT same condition I have. I used to run on 25% rapid and after a tool change it would take off at 100% and then hang on the next change. I can say that I don't think temp has anything to do with it. It has run in a shop that was cold (55 degrees) and now in a shop that is around 70. It even did it in the summer. My machine will hang all day long. I originally thought that it might be electrical noise from my sharp lathe. The problem got worse after we installed that, but it still does it even if the lathe is not running. It is very frustrating and a huge waste of time.

  5. #5
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    Mickey D,

    I have had that problem as well, where the machine would just stop, mine usually in the middle of a cut. Push the start button and all would be cool again. I think my compressor might be a little low on the low side. I also know that my regulator on the back of the machine is set to about the middle of the yellow. I adjusted it up awhile ago and did not see any difference so put it back where it was. I will try those 2 changes together and see what happens. Spock, can you tell me what your compressor / regulator settings are? Maybe we might be on to something. I did read another post that talked about limit switches in the spindle gear box. Maybe the controller is not getting a signal it needs. I am not too familiar with that stuff and have no idea what the "Ladder" is.

  6. #6
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    Talking Cycle progress.

    I've had similar problems on an rather large OKK CNC with a Bosch Controller.
    Part of a cycle to say change a tool operates various mechanisms in sequence.
    Cycle starts first part of sequence. Waits for a limit switch to say that part of cycle is complete.
    Next step commanded, wait for next limit switch.
    Each sequence starts moving something.
    That sequence is usually completed by hitting some limit.
    Eg Tool picker at location ready to pickup a tool.
    If any of the limit switches are not sensed correctly, or at all then the cycle waits, hence the green light just waiting.
    Also some parts of sequences may be progressed based on timers instead of limit switches. If a time is set to short, or something does not move fast enough to get to it's next spot, because it's gummed up that can do it too.

    Easiest thing with limit switches is putting a 0.1uF Capacitor across the switch, so you get the capacitor supplies extra wetting current to keep the contacts clean. This is usually a safe fix, if no capacitor is across a switch.
    If it causes some operational grief, then just remove it.

    When the machine is 'stuck' try thumping around the areas where the limit switch(es) are/is and you may identify it. Careful of unexpected movement if the machine normally moves FAST.

    Every case I have had on an aging machine has been tardy limit switches.
    Clean plunger mechanisms and get rid of gummy old lubricant.

    May appear temperature related, because lubricants get more sluggish at low temperatures.

    Also look at connector plugs. Make sure all pins have positive pressure.

    Search and destroy....... It will fix it. Don't blame software. It is just doing it's job. If it worked yesterday, it ain't broke.
    :cheers:
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  7. #7
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    I am 100% sure it aint software, it is mechanical.

    My air compressor runs between 140 and 170 on pressure.

    My regulator on machine is set to .65 Mpa, near the top of the yellow.

    The idea that there is some grease on a switch, getting cold and stiff, and not allowing it to move freely makes sense to me. Then, the switch cant send it's signal, in the ladder schematics in controler it defaults to 100%, machines until the next toolchange, then hangs up waiting for signal.

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    I agree Spock. It does make sense that it could be a limit switch. Do you have the same machine? A sharp sv2412? Anyways, I will be running it today and I am sure it will hang. I will try Neil20's suggestion of banging around where limit switches are and see if that might be it. I think before that, I will take a good look at the Z axis limit switch that I can see. Lets work together on this one and see what we can find out ?

  9. #9
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    I had that issue on the loaner machine I had for a couple of months. Charlton Lu told me to add a bit of dwell fro the limot switched in the tool change macro. That cured it na dI also did the same for my machine. I have not had any issues. I do keep the pmachine pretty clean though. Limit switched being what they are...

  10. #10
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    I have a sv24-12 super mini with OI-MC control.

    Adding dwell was what the dealer service did, and it seems to have helped alot, but didnt cure it for mine.

    I keep my machine very clean, but I think when repairman gets here on Monday I will have him go thru switches with contact cleaner or something, check for anything loose, etc. Thing is, my machine did this when brand new, no chips or dried sticky coolant or anything!
    I will let you know if we find anything out.

  11. #11
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    Well another day of machine frustration. Did some bangin around with a rubber mallet. No luck. Checked what limit switches I could find. Not sure where they all are. How would I add more dwell in the tool change macro? I am pretty handy with computer stuff so if I knew what value to change I will give it a try. Also here is something I noticed. When the machine hangs, I can rotate the spindle freely. I know from experience that when I do an M19, the spindle is locked in its oriented position. Could the issue be here? Spock, let me know what the repairman says. Thanks.

  12. #12
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    I'll send you my tool change macro in the morning if you send me an email...

  13. #13
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    Question Limit switch here?

    Quote Originally Posted by javajesus View Post
    Well another day of machine frustration. Did some bangin around with a rubber mallet. No luck. Checked what limit switches I could find. Not sure where they all are. How would I add more dwell in the tool change macro? I am pretty handy with computer stuff so if I knew what value to change I will give it a try. Also here is something I noticed. When the machine hangs, I can rotate the spindle freely. I know from experience that when I do an M19, the spindle is locked in its oriented position. Could the issue be here? Spock, let me know what the repairman says. Thanks.
    There may be a limit switch to detect spindle unlocked.
    If so it must be satisfied for further progrees.
    Does anything happen after the spindle disengages?
    The unlocking maybe of an electronic nature, with no switches, in which case this won't be the problem.

    Press on...
    regards.
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  14. #14
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    What must be understood is that the 1st thing the machine does wrong is come out of a toolchange and take off at an unspecified rapid traverse rate. When it does this, it reads every G0 code in the program and goes 100%, regardless of the switch setting. It reads G1 correctly.

    The hangup comes after it has executed all the code for that tool, and goes to change position in Z, starts reading thru the toolchange macro, and then hangs at M6.

    If i run a single tool program with no change it will still take off at wrong rapid rate sometimes, then do the machining, and return to Z home. I change parts, hit cycle start again, and it takes off again at either the right or wrong rate, but there is no hangup then because there is no toolchange.

    That leads me to think that the problem is not toolchange related, but that the hangup is a symptom, and the culprit is whatever lets the machine take off at the wrong rate to begin with.

  15. #15
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    Spock
    Is this a 0iMate control or a 0iMc?
    Never had it happen to me but I have a 0iMc control not the Mate...

  16. #16
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    Bosch Control similar.

    I have seen the Bosch controller lose the feed rate setting.
    In the PLC the part that reads the feed rate pot got screwed up because of unexpected sequences with limit switches. Problem appears to be earth/noise problem. Make sure all the cable shields are connected properly. (usually at one end only).
    Sounds like earthing problem at pendant or where FEED pot is located.
    I suspect that during the normal PLC scan, the feed pot has been read incorrectly. There also could be a noise spike from some other fault coincident with the reading of the pot.
    I notice on this controller, the feed pot is also sampled when manual control is selected to/from remote jogging. This sometimes read the wrong value. Again
    bad earthing fixed it.
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  17. #17
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    PBMW,
    I have the OI-MC. And I really like this little machine, but I want to get rid of this bug. It is bad when I have to walk across the shop to restart a program, but what is worse is that when the machine takes off at 100%, you better have everything right or something is going to get hit hard.

    neilw20, last time the tech was here he checked the signals, and I honestly cant remember the details, been several months. I remember that there was a place for 2, and they determined what the rapid rate was.

    Is it possible that electrical noise might be a culprit? Could interference from another source (machine?) hurt? I am having some issues right now with interference in my phone system. I just put in cat5 cable to see if it helps. The way it has been lately, whenever I am on the phone and I have a spindle motor slow down real fast, I get serious noise in my phone. Could this be affecting the scan? Over my head here.

  18. #18
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    We have just had the same problem with our 2412, it ended up being an adjustment in the head that has to be made manually. I am not sure what the exact fix was because I was not the one doing the repair but it was an adjusment to the limit switch from what i remember. The machine had just hung in tool change position and the only way to fix it was to hit the emergency stop(dont do because the tool will fall out). Once the adjustment was made we had no further problems with the machine hanging up. Sorry I cant give exact details to the fix but I can tell you that it is a limit switch for the tool change.

  19. #19
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    Limit switch, had the same problem and now it is fixed.

  20. #20
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    Phone interference.

    Quote Originally Posted by spock View Post
    PBMW,
    I have the OI-MC. And I really like this little machine, but I want to get rid of this bug. It is bad when I have to walk across the shop to restart a program, but what is worse is that when the machine takes off at 100%, you better have everything right or something is going to get hit hard.

    neilw20, last time the tech was here he checked the signals, and I honestly cant remember the details, been several months. I remember that there was a place for 2, and they determined what the rapid rate was.

    Is it possible that electrical noise might be a culprit? Could interference from another source (machine?) hurt? I am having some issues right now with interference in my phone system. I just put in cat5 cable to see if it helps. The way it has been lately, whenever I am on the phone and I have a spindle motor slow down real fast, I get serious noise in my phone. Could this be affecting the scan? Over my head here.
    Use the phone to call a VERY experienced CNC doctor/installer/designer. Not just a serviceman. A soundly designed earthing system design is a MUST.
    If somebody says they will TRY something go somewhere else.
    This problem must be analyzed and fixed.
    How much is the machine worth?
    Phone noise probably normal from motor control. Long cables will do that.
    If the program is resuming part way through, a command in the tool cycle has may have selected G0 as a part of the tool change cycle.
    After each TOOL CHANGE, before any move put G1 on the next line.
    If that works, your tool change cycle is badly written.
    Do you use G0 for rapids within a program?
    It is a good idea to only use G1, and do rapid moves in a controlled manner by selecting a high feed rate for the move. This is good practice
    Any sub program that does something, such as change a tool, or whatever, should leave the machine in the same state as it found it, unless the intention is to change something.
    As protection against this problem I have noticed the bosch controller forgets the feed rate on purpose after a tool change, which then causes an error G1 move without feedrate selected. Also, if no feed rate selected, G0 does not work.
    Buy me a ticket to visit you (and return!) and I will fix it for free. You buy the parts! (LOL)
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

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