What factors affect duty cycle in a mig welder?

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And can one do anything to help improve it if you are stuck with the welder you have? Does welding cable length or diameter matter, for example?Thanks,Russ
Reply:What are you trying to achieve? What type of machine do you have? The duty cycle of the machine is what it is at the specified ratings. You lead length and cable size will effect the output at the lead end. The longer the lead the more you need to increase the size of the cable to maintain the output. You also need ot factor in the ground cable as well, the complete loop._________________Chris
Reply:I could be off base on this, but my understanding is that the heat generated and not dissipated from the transformer is the reason for having a duty cycle.  If you could cool the transformer more effectively, you could substantially increase the duty cycle.Smithboy...if it ain't broke, you ain't tryin'.
Reply:My main question was just an "in general" type. I have a Lincoln HD mig something or other that I bought used. I don't remember the exact model, haven't had it too long and it is at my old house currently in another town, so I can't look at it to see. I haven't even had a chance to use it yet.But for example, what happens to duty cycle if the welding cables are shortened? Does that allow you to weld for a longer period of time before the machine shuts down? Same with adding a fan to the case. Maybe I didn't explain myself too well initially. What I am after is what can I do to make my welding machine's life easier? Going out and buying a new one because I killed this one is not a good option for me.  Adding a fan to the case is something I can do, for example, if that will improve things. Or, put it this way. I am basically a hotrodder at heart. Are there things I can do to hotrod the welder to improve it?Thanks,Russ
Reply:Originally Posted by russ69coupeMy main question was just an "in general" type. I have a Lincoln HD mig something or other that I bought used. I don't remember the exact model, haven't had it too long and it is at my old house currently in another town, so I can't look at it to see. I haven't even had a chance to use it yet.But for example, what happens to duty cycle if the welding cables are shortened? Does that allow you to weld for a longer period of time before the machine shuts down? Same with adding a fan to the case. Maybe I didn't explain myself too well initially. What I am after is what can I do to make my welding machine's life easier? Going out and buying a new one because I killed this one is not a good option for me.  Adding a fan to the case is something I can do, for example, if that will improve things. Or, put it this way. I am basically a hotrodder at heart. Are there things I can do to hotrod the welder to improve it?Thanks,Russ
Reply:Duty cycle is part of the design of the machine.  The machine is designed to handle only a certain amount of power for a certain amount of time before it gets too hot and has to cool off.Duty cycle on a welder has nothing to do directly with how long your welding leads are.  The welding lead length does have a relation to the duty cycle though, because if you have too long leads on the machine and you are losing too much amperage in the leads then you would try and compensate by turning up the amp output from the machine which means the machine is now working harder.  Also, your leads will get hotter if they are long, thin, or you have more amperage going through them.To make the most of the machine you have, as Rojodiablo said, make sure it isn't crudded up with dust and crud and make sure it has cooling air able to flow in and out through the machine's vents (don't jam it in back against a wall or cover it with a tarp or welding blanket to keep 'clean', without air flow it will overheat.)Using a machine within its limits will help it work better.  You're not going to weld 1/2 inch plate with a little 120V MIG unit, it just can't put out enough heat/amps.  Those little machines really shine on thin stuff, sheet metal up to 1/8 inch stuff is usually within their comfrotable limits.  Using them for heavier/thicker stuff starts to depend more on operator skill and work prep and you may hit duty-cycles limits then.And in case you didn't realize it, duty-cycle for welders depends on the amp output being used.  If you turn the amps down, your duty cycle usually goes up.  A typical 120V MIG unit might be rated at a 20% duty cycle at 90A output (2 minutes of continuous welding/arc time and then 8 minutes of idle cooling time), but might have an 80% duty cycle at 40A output (8 minutes of continuous welding/arc time and 2 minutes of idle cooling time). [Millermatic 135, because Miller has nice graphs of duty-cycle vs amperage output in the manuals.]Heat build up is the primary factor in the duty cycle rating, so try and keep the machine cool and let it flow its cooling air like it was designed to.To hot-rod the welder, you could run vortex coolers if you really want to try and push the machine hard.  But just remember that you only have so much power coming out of any machine.  Just like you can't use a 1/4" socket wrench to torque a big bolt to 700 ft-lbs no matter how long a cheater bar you put on it.