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  • Run time before overheating unit?

    I know somewhere I read that I should not run my hobart 187 mig for more than 10 minutes welding?

    Does that mean I need to shut off the unit after 10 minutes of welding to let it cool ? I usually weld for 3-4 minutes and then walk away for 5-10 minutes and let the welder sit there in the " ON " position with the fan running. Is this proper procedure for keeping the machine at a happy temperature?

  • #2
    No, no, no...the 10 minutes relates to duty cycle...for example if the duty cycle is 60% then this means you can weld at maximum current wide open for 6 minutes before the thermal overload breaker kicks in and shuts off your machine for 4 minutes.

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    • #3
      It's like Rocky said, but I wouldn't worry too much about it. The worse case scenario is the theraml overload trips, but I've never had that happen on any of the three MIG machines I've owned.

      I can't normally hold a position that will allow me to weld up to the duty cycle without stopping to reposition something - either me or the work!

      Hank
      ...from the Gadget Garage
      MM 210 w/3035, BWE
      HH 210 w/DP 3035
      TA185TSW
      Victor O/A "J" series, SuperRange
      Avatar courtesy of Bob Sigmon...

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      • #4
        Gotcha guys!

        So letting it sit with the fan on is not going to hurt the machine right?

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        • #5
          Originally posted by 9 LIVES View Post
          Gotcha guys!

          So letting it sit with the fan on is not going to hurt the machine right?

          That's correct. Won't hurt nothing with the fan on.

          556man

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          • #6
            Someone else correct me if I'm wrong, but I think it would be better to leave the fan on if it does overheat. That way it's drawing cold air by the transformer to cool it better. Then again, maybe the thermal switch kills power to the whole machine when it trips, but I doubt it.
            HH210 w/spool gun
            HTP Invertig 201

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            • #7
              leaving the fan on is beneficial to the welder. it helps to cool the transformer more quickly. shutting it off when it's hot can only help to shorten its life. i leave mine on for a few minutes after my last weld, and check to see if the exiting air is cool before shutting it off. maybe i'm a bit cautious, but i like to baby my new machine.
              5 rules for happiness:

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              5. expect less


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              • #8
                9Lives, You do not want to know the run time till the 187 overheats. What you want to know is how long you can weld BEFORE it overheats. Overheating is a bad thing cause repeated overheatings cause the smoke to come out. Thus the Duty Cycle is born. First consult your manual Section 4.2. Down loadable from Hobart if necessary. I got the generic cause I do not have your machine serial number. This section explains Duty cycle and overheating. Note the bold lettering stating "Exceeding duty cycle can damage unit or gun and void warranty". You exceed the duty cycle, barge into the safety zone and overheat the welder to many times, it will let the smoke out rest assured. A chart is provided to help keep you in the duty cycle and out of overheating. For example : @ 135 amps the duty cycle is 30%. That means in a 10 minute period of time you weld for 3 minutes and don't for 7. This keeps things cool. Cool is good. Notice that at 75 amps your duty cycle is 100%. Weld all day long continuously.
                By welding for 3 or 4 min and walking away leaving it run for 5 or 10 min you are utilizing a duty cycle of sorts. You should in no way turn the unit off if it does overheat as that stops the fan cooling thus creating a temperature spike.and maybe some smoke coming out.
                If you are like me, once the hood is down I can't see my watch, but you could have a wall clock, look at the time, weld a bit, stop, glance at the time to get a feel for the duty cycle. Hope this helps you out.
                Last edited by Mr Meck; 11-08-2007, 01:04 AM. Reason: That english thing

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                • #9
                  Mr. Meck:

                  I read your post with some difficulty due to my current state of sobriety, and your lack of pagination, but I think I got the gist.

                  My question to you, the theory you explained notwithstanding, is how often in your GMAW experience have you exceeded the duty cycle to the pont that the thermal overload has operated, and how many times have you seen a machine "let the smoke out" because of it?

                  Just curious, as it flies in the face of my, admittedly, meager experience, yet I've welded some pretty good projects with the MM 210, without issues, at tap 6 and 80 on the WFS running .030.

                  Hank
                  ...from the Gadget Garage
                  MM 210 w/3035, BWE
                  HH 210 w/DP 3035
                  TA185TSW
                  Victor O/A "J" series, SuperRange
                  Avatar courtesy of Bob Sigmon...

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                  • #10
                    Hank,

                    Mr Meck is correct in his definition of duty cycle. Duty cycle is defined as the percentage of time a machine can be operated at a particular amperage in a 10 minute period. In other words, if the machine is rated for a 40% duty cycle at 100 amps, the welder should only weld for 4 minutes in a 10 minute period, letting the machine cool for the remaining 6 minutes. Machine should remain on with fan running during the cool down period.

                    We all know the MM210 is a very robust machine and that Miller tends to be very conservative in their duty cycle ratings. As you have stated, most welders, due to having to reposition the work, adjust position, etc., never run up against the machine's "duty cycle". Ambient temperature also plays a big role in the actual machine's duty cycle. As the ambient temperature goes down, the duty cycle goes up and inversely, as the temperature goes up the duty cycle goes down.

                    I think duty cycle is much more a factor in the smaller machines where the duty cycle tends to be in the 30% range of their rated output. For the guy who's "pushing" a smaller machine, duty cycle becomes much more of an issue. For instance the MM140 is only rated at 20% duty cycle @ 90A/18VDC or 63A/21VDC whereas the MM210 is rated at 60% duty cycle @ 160A/24.5VDC.

                    What I find interesting is that it seems that all manufacturers rate their machines based on amp output, yet the machines only have voltage taps (or voltage adjustment) and wire feed speed (wfs). I guess they expect the user to go to the graphs and figure out how many amps they're really pulling out of the machine.
                    SundownIII

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                    • #11
                      Originally posted by SundownIII View Post
                      Hank,

                      Mr Meck is correct in his definition of duty cycle.......
                      I agree. That's not the point I was trying to make. Just my opinion, but I've not seen, in the "real" world, a significant number (any, for that matter) of machines that have "let the smoke out" due to overworking past the duty cycle norms.

                      My point was prpbably not very well stated, but what I'm trying to say is the duty cycle is no "big deal" as far as damage to a welding machine is concerned. Thermal trips due to long weld times are few and far between, in my experience.

                      Sorry if I confused anyone!

                      Hank
                      ...from the Gadget Garage
                      MM 210 w/3035, BWE
                      HH 210 w/DP 3035
                      TA185TSW
                      Victor O/A "J" series, SuperRange
                      Avatar courtesy of Bob Sigmon...

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                      • #12
                        You're nit-pickin, again Hank... I would only add here that the duty cycle is based on running maximum welding parameters...running wide open....less than that, and the duty cycle increases percentage wise. But that's nit-pickin too.
                        I have tripped the TOP (thermal overload protector) many times on a MM130 at work, where I had to weld 6' of trench plate. Ya really need 100% duty cycle for long continuous welds. It's a royal PIA to have to wait for the machine to cool down.

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                        • #13
                          Did you wish for wish for 2nd welder during cool down?

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                          • #14
                            Rocky,

                            In your case, I don't doubt it! I still remember the pictures you posted a few years back!

                            Hank
                            ...from the Gadget Garage
                            MM 210 w/3035, BWE
                            HH 210 w/DP 3035
                            TA185TSW
                            Victor O/A "J" series, SuperRange
                            Avatar courtesy of Bob Sigmon...

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                            • #15
                              Originally posted by Rocky D View Post
                              No, no, no...the 10 minutes relates to duty cycle...for example if the duty cycle is 60% then this means you can weld at maximum current wide open for 6 minutes before the thermal overload breaker kicks in and shuts off your machine for 4 minutes.
                              Just to clarify, though I know Rocky D knows this, most machines are not rated at their maximum outputs but at a lower "rated output".

                              For example, my MM175 was rated at 130A for 30%, so it would be even shorter at 175A, which it is capable of doing.

                              And I tripped its thermal overload a few times before I got bigger machines. It stops weld output and sits there with the fan on.

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