On these machines, do I have to be counting duty cycle, or can I just weld until the thermal shutdown kicks in, then give it a rest?
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On these machines, do I have to be counting duty cycle, or can I just weld until the thermal shutdown kicks in, then give it a rest?
Heat is the arch enemy of semiconductors. You can finds scores of graphs and curves of temp and lifespan. So for the most longevity you would be wise not to rely on the thermal sensor. It is on the heat sink and it will take time for it to reach the trip temp while the actual junctions continue to heat up. There is also hot soak and many other factors that come into figuring out a duty cycle. For some production shops, time is the most valuable asset and they will burn up machines pushing them to the limits routinely, then just swap out units when they die. For most of us, we run at a slower pace and it's not hard to stay under the duty cycle. Things like ambient air temp, humidity among others, can also effect duty cycle. If you are working your machine hard, give it a rest before it demands it, and it will give you many years of good service.Quote:
Originally Posted by joshuab
Everlast welders have huge fans andheat sinks which increase their duty cycles over some others,,,,if you can weld to the point that exceeds the duty cycle ,,then you are one hellva welder and should slow down cause you are working too hard..or maybe come over to my place I could use a guy like you..Quote:
Originally Posted by joshuab
Understand Duty Cycle
What is the definition of duty cycle?
The amount of time in a ten-minute period that an electrical device can perform work without overheating.
One way of classifying a welder's "size" is by how much amperage it can generate at a given "duty cycle." Duty cycle is the number of minutes out of a 10-minute period a welder can operate. For example, the Everlast 250EX TIG unit can deliver 250 amps of welding output at a 60 percent duty cycle. It can weld continuously at 250 amps for six minutes, and then must cool down during the remaining four minutes to prevent overheating. Six minutes of welding at 250 Amps is a lot of welding but at 200 amps it can weld at 100 percent all day under normal conditions with out over heating.
Running your welder to the duty cycle is like running your car to the redline in the temperature range and then letting it cool off. Do that routinely and intentionally and you will have a car and welder with issues.
That's really what I was wondering. "Is the thermal shutdown point the red-line, or is it some point less than that?" Seems like I've got my answer. Maybe I should invent a "duty cycle timer". It could sense the arc and count how many minutes out of ten you have been welding, and tell you when to stop. I'll be rich!Quote:
Originally Posted by performance
So, let me ask a different question then: how do y'all track your duty cycle? I know you're not out there with a stopwatch. Are you just winging it?
I buy a large enough machine for my usage that I don't have to worry about it too often.
What type of welder is it and what are you welding?Quote:
Originally Posted by joshuab
Duty of a welder shouldn't really ever be an issue at all unless you are using it commercially. It is difficult to use a welder at full output for a long period of time unless the welder is too small for the job you are trying to do with it.
Joshua,
When it is your dime, you learn pretty quickly how to take care of it. But experience will be the best judge you'll ever have. Time yourself on how long it takes you to weld a couple of welding rods continuously. Note the size/type etc. This will give you a pretty good marker on the duty cycle that you are doing. Years ago, 60% was the standard, and it was the standard because that was typically the time ratio of weld vs. chip/clean that you'd do. That's how the whole 60% duty cycle first came around. You'd weld 60% and clean and chip the other 40% before you needed to weld again.
Thanks, Mark. Now that I think about it, I do remember once hearing that a 1/8" rod should take about a minute to burn, so you could use that as a metric for your duty cycle. Still, I wasn't sitting there with a clock over my head marking ten minute increments before I could go back and burn another rod. With my old buzz-box, I was constantly running with the thing around 120-140, and 140 was its max output. Suffice it to say, I probably exceeded the duty cycle at least once. I feel a little better with my PA160-STH, since it's rated for 60% at 120 amps, which is usually top end of the ballpark that I'm in.
Welding 6 minutes out of 10 is quite a long time. For stick, you'll definitely be hard pressed as you'll need to replace electrodes and clean off slag, etc as Performance indicated and electrode size will dictate maximum amps used. It will also be tough to max out your amps MIG welding. For TIG welding if you intend on welding up beefy aluminum, you'll need to size your welder appropriately and there are calculators for common joint types, materials and amperage required to help you get a feel for that. If you don't see yourself going there, sizing your welder will be much less of a concern.Quote:
Originally Posted by performance
Duty Cycle by Everlast on a PowerTig 250EX
The duty cycle has been determined for the 250 EX (220/240 V 1 and 3 phase ). For the 250EX, the duty cycle is rated for 60% at 250 amps. The duty cycle is based off a 10 minute duty cycle rating at 40° C. This means that the unit is capable of being operated at the stated amps for 6 out of every 10 minutes without a break to cool down the unit. This does NOT mean that the unit can work 60% of any greater length of time. A full 4 mi-nute rest should be given to the welder for maximum life. The temperature light will come on and the welder will automatically stop welding when an overheat condition has occurred. If the light is on but the unit does not stop welding, this does not necessarily mean that you have not exceeded duty cycle. Heat will continue to be generated by and transferred to the electronics after welding has ceased. Welding in humid, or hot conditions can affect duty cycle as well. Do not shut down an overheated welder until it has safely cooled. Once the overheated condition has cleared, welding can resume. Do not oper-ate the welder with the covers removed.
I think if you have to keep running your welder at full power you need a bigger machine.
I could use a bigger machine but I only have single phase 220V can get the voltage up to 600V with a transformer but still only single phase.
At the typical 5-8 ipm for SMAW, that 60% translates into about 30-48" of weld. Quite a lot for a non-industrial setting. By industrial, I mean where you might have hundreds of parts all prepped to weld. For typical fabrication, even after something is all tacked and you are welding it out. It's really hard to get in 48" of nonstop welding without pausing to re-position either the part or yourself, chip, clean, grind, answer the phone, chase out the cat, yell at the neighbor, etc.
I think you're totally right. If you're running at about 60% duty cycle, that's more than enough for most any user. I guess I'm kind of conditioned to worry about it since my other welder had only 20% at the outputs I was running. I guess this is really the answer: most people have a welder with enough duty cycle to not have to think about it too much.Quote:
Originally Posted by Rambozo