Haas Belt Drive Bar Feeder
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  1. #1
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    Default Haas Belt Drive Bar Feeder

    Anyone else having problems with their newer Haas bar feeder that uses a timing belt? Mine worked till a little past the warranty period and has turned into one PIA since. The issue is the belt slips on the drive pulley. HFO has installed a new belt onto the feeder and has been having the same problem. The belt had a sideways curve to it, looks to me an issue with too much tension and too much torque for the system. It feeds fine for about the first 3 feet of a 4 foot bar and then it looses position by slipping the pulley. The step where is slips is in the pulling the pushrod back. This step the feeder moves at 100% rapid. Is there a way to slow this action down?

    There are three permanent fixes to this problem system.

    Firstly would be slow the rapid down on the pushrod return. Does not look like this is operator accessible.

    Secondly using a bigger pulley on the servo drive motor. Of course this would require a parameter change to the control and I am still not sure that the current timing belt can stand up to the torque for long periods. Probably would still still require slowing of the rapids. Also thought of making the pulley longer, 2" wide instead of 1" and keeping the diameter. The changes that require Haas to change parameters are probably out.

    Thirdly would be to replace timing belt with a chain drive. I am slowly thinking that this is the way to go for a bulletproof drive system. I am sure that Haas did not go with a chain is they would have to lubricate it and the timing belt requires none.

    This bar feed system should be more robust than what I have encountered. I operate a job shop where we tune 1" dia to 3" in less than 1000 piece orders. Cant imagine using where it ran for long periods without operator intervention.

    Any comments would be appreciative. Thanks

  2. #2
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    i was working on that exact problem recently.

    i don't think changing the velocity makes any difference because the barfeeder trolley never reaches max velocity anywhere in its routine. what i think is happening is that the slack on the belt flips sides when it goes from accel to decel, which could be enough to make the belt skip.

    when the belt skips, is it throwing an alarm right away?

    what i DID see was someone removed the spring in the tensioner and used a bolt and some washers to tighten the shit out of the belt

    the belt is probably good for 400 lbs, but i suspect the bearings on the pulleys will fail well before that.

    either way, i suggest hounding your HFO about this.

  3. #3
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    have you disconnected the belt and ran the rabbit up and down the full length of travel? wondering if your into some sticky spots not letting free travel happen.

  4. #4
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    Default

    We bought two new barfeeders recently and the issue was actually too little belt tension. Tightened 'em up and they haven't had any issues since. We knew the problem was rapid-related because the barfeeders worked perfectly with the doors open (which reduces rapids to 5ish percent).

    From the factory, you could take off the front cover and easily twist the belt 360 degrees by hand. After upping the tension, it's more like 180. Not scientific, but somewhat repeatable.

    I believe Haas has a patch config that will take down the rapids to 75%. I haven't done that yet as I wanted to see long term if the belt tension fixes it. So far no issues. We recently ran a 5-day (120 hour) continuous cycle on one of the ST20Ys.

    Note that if your loss of position caused any bumps, you'll want to recheck the alignment of the everything, especially the push rod arms. They're design to slip rather than destroy themselves.

  5. #5
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    After contacting my Haas HFO, the applications team responded in a timely manner. They replaced the belt a second time and replaced both pulleys. A little wear was found in the pulleys cogs, corners were not a crisp as the new ones. The applications team did install the 25 percent rapid reduction patch. This makes it run a lot a lot smoother, no need for such a fast rapid. I would recommend to have this patch installed on all these machines. Maybe give it a fighting chance. Have not had a chance to run it after changing these. They did run the test program that runs the carriage back and fourth to see if it jumped. It was fine.

    FYI This feeder is a year and a half old with 1500 spindle hours on ST-25y with sub-spindle mostly running feeder type parts. I have run the machine for 2 weeks straight 3 to 4 times without problems. So the machine can be run with fast retract but will eventually wear out pulleys and belt.

    The tech guys did take the drive end of the feeder apart noting that on other feeders they had worked on, an ill aligned clutch on the bar loader mechanism made the machine clunk when loading new bar. The clutch shaft key needs to be aligned with the lug or it will not work smoothly. If you have this problem I can get you in contact with the tech. Let me know. Sorry, I should of taken pictures.

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