Thread: Which mig?

Originally Posted by Lyle

Duty cycle has me confused now as I've heard different quotes. Seems you need to know to ask what the duty cycle is at a specific current/voltage. "oils ain't oils" so it seems.

Lyle.

Duty cycles are a strange thing to be honest as people assume they are all based on the same period of time and under the same conditions. All major manufacturers I am aware of use a period of 10 minute at 40 degrees celcius to measure their duty cycle but have heard companies (mainly chinese) using a 5 min duty cycle period.

Ive seen inferior chinese copies of original equipment that has a higher duty cycle that the item they have copied!!

I have rarely seen a copy that was a good let alone better than the original??? So I would take most of the duty cycles with a grain of salt on most of the chinese products.... The only time most hobby welders are going to exceed the duty cycle is when the are tacking things together..... Alot of tacking = 100% duty cycle due to the fact the machine/gun doesnt get a chance to cool down.

Most of the time the gun is the thing that will suffer the most as the machine most probably has a thermal overload anyway.... How many of you own these 200 amp AC/DC machines....There is no gas cooled tig torch available on earth that has is rated to handle 200 amps AC... DC yes but AC no... and if you have pulse take another 30% off.... But most people wont weld that high anyway....

Hope this helps?? Probably just confused you more??

Cheers Rappy

Originally Posted by Lyle

MacManLuke are you any closer to your decision?
What have you narrowed it down to? And why?

Lyle.

Still not sure!

Pretty sure im going to avoid chinese designed machines.

Then its the job of deciding between inverter and transformer.

Transformer seems more tried and tested / reliable but heavy

Inverter seems to offer more and be lighter but more sensitive to voltage / treatment.


Also considering spending a bit more and going for a 200+ amp model for more versatility.

Hey luke

Try have a look on machines4u.com has most well known brands on there and are sold by most of the best welding shops around australia....Need anymore help just ask....have sold a few welders in my time...not trying to sell you one just hopefully giving you ideas...

Cheers Rappy

good site!

But makes the decision harder! eg Esab is in the price bracket and i believe they are a good machine? also Cig 200 looks good, full trolley chassis and a few amps more for not much more than the 170-190 amp machines (transformer machine instead of inverter 175)

all too hard! so many similar options in the same price bracket

Hi Luke,

If I may suggest something, don't let price dictate the purchase, list your criteria, fulfill it with an array of product and then filter by price last. I find the below points helpful to fulfill the criteria part.

1. Do you need portability, pick up and carry etc? If yes go for inverter, if not go for transformer.

2. What amperage do you need to weld at? If you are planning to mainly weld at say 150 amps then look for a machine that can deliver that amperage at a realistic duty cycle. If for example the duty cycle is 30% at 150 amps ask yourself if you will be welding for 3 minutes non stop at 150 amps on the hottest day of the year. With the 60974.1 standard duty cycles are quoted at percentage use in 10 minute periods at set amps for 40 degrees ambient air.

3. Do you need to weld to a schedule? For example do you need to weld for a living and need to get jobs done on time for customers irrespective of the temperature. If this is the case look to point two above and then go for the 100% duty cycle rating at the amperage which you feel will cover your requirement. This will ensure you are never let down by the machine when you need it most.

4. How much overhead do you need? Sometimes you may need to weld at a higher amperage than the usual, with this in mind you need to pick a figure that you are happywill suffice as your overhead and ensure the welder can deliver it. Duty cycle will be very low at the upper limit so you need to keep this in mind. Current Vs Time Curve - A transformer machine will dip it's current output very quickly at it's uper limit as the transformer increases internal resistance due to temperature rise. For example you can see plenty of 200 amp transformer welders on ebay for $299. Yes they can weld at 200 amps but only for a very short time as the current diminishes very quickly with temperature, these machines are generally capable of only sustaining 60 -80 amps at 100% duty with a very rapid drop in their current vs time curve. An inverter machine on the other hand has it's current limited by the ability to dissipate heat from the inverter transistors so can sustain overhead for longer without an obvious curve but will shut off once the thermal trigger is activated.

5. Longevity - This can only be achieved with a transformer machine , it has no moving parts other than motor or fan (easily serviced) and if suitably protected with a thermal cut out will never suffer from dielectric break down. The speed controllers are PWM types and can be serviced in the field with parts available at Jaycar (simple timer, capacitor, SCR, transistor) To clarify, transistors are like moving parts...they are electronic switches and are rated in switching cycles so do ultimately have a life limit.

6. Purity of DC in the arc - Inverters have a cleaner DC as it has a 25Khz+ of ripple as opposed to Transformer machines with 50Hz ripple however you can add capacitors to a transformer machine to clean up the DC component.

7. The torch - The torch has a duty cycle also and is generally less than the machine. With gas shielded welding you get some cooling however with flux cored wire you will need to increase the torch head to accomodate this or else provide alternate cooling.


Hope this helps you
Pete (Tokentools)

Originally Posted by mac_man_luke

good site!

But makes the decision harder! eg Esab is in the price bracket and i believe they are a good machine? also Cig 200 looks good, full trolley chassis and a few amps more for not much more than the 170-190 amp machines (transformer machine instead of inverter 175)

all too hard! so many similar options in the same price bracket

Originally Posted by inverter_weld

Hi Luke,

If I may suggest something, don't let price dictate the purchase, list your criteria, fulfill it with an array of product and then filter by price last. I find the below points helpful to fulfill the criteria part.

1. Do you need portability, pick up and carry etc? If yes go for inverter, if not go for transformer.

I dont really see the need to be able to pick it up and move it because it will be used im my shed with a smooth concrete floor (so trolley with wheels will do for moving it around)

If i was going to move it, id most likely be taking it outside where id prefer to use a stick welder anyway (got a small AC unit which is ok)

2. What amperage do you need to weld at? If you are planning to mainly weld at say 150 amps then look for a machine that can deliver that amperage at a realistic duty cycle. If for example the duty cycle is 30% at 150 amps ask yourself if you will be welding for 3 minutes non stop at 150 amps on the hottest day of the year. With the 60974.1 standard duty cycles are quoted at percentage use in 10 minute periods at set amps for 40 degrees ambient air.

At this stage i dont really know what amps i will be welding at other than i know i want it to be good at low amps for possible car restoration project

Also because its a hobby, i cant imagine ill ever be super fast at prep work etc that id really catch up with the duty cycle (and i wont be working @ 40ºC either)

3. Do you need to weld to a schedule? For example do you need to weld for a living and need to get jobs done on time for customers irrespective of the temperature. If this is the case look to point two above and then go for the 100% duty cycle rating at the amperage which you feel will cover your requirement. This will ensure you are never let down by the machine when you need it most.

Answered in the previous point, nope - always going to be for "fun"

4. How much overhead do you need? Sometimes you may need to weld at a higher amperage than the usual, with this in mind you need to pick a figure that you are happywill suffice as your overhead and ensure the welder can deliver it. Duty cycle will be very low at the upper limit so you need to keep this in mind. Current Vs Time Curve - A transformer machine will dip it's current output very quickly at it's uper limit as the transformer increases internal resistance due to temperature rise. For example you can see plenty of 200 amp transformer welders on ebay for $299. Yes they can weld at 200 amps but only for a very short time as the current diminishes very quickly with temperature, these machines are generally capable of only sustaining 60 -80 amps at 100% duty with a very rapid drop in their current vs time curve. An inverter machine on the other hand has it's current limited by the ability to dissipate heat from the inverter transistors so can sustain overhead for longer without an obvious curve but will shut off once the thermal trigger is activated.

I really dont know at this stage, thats why im leaning towards a bigger machine if i can justify it

5. Longevity - This can only be achieved with a transformer machine , it has no moving parts other than motor or fan (easily serviced) and if suitably protected with a thermal cut out will never suffer from dielectric break down. The speed controllers are PWM types and can be serviced in the field with parts available at Jaycar (simple timer, capacitor, SCR, transistor) To clarify, transistors are like moving parts...they are electronic switches and are rated in switching cycles so do ultimately have a life limit.

I really would prefer to get something that will last but its never really going to be mistreated eg will be in a clean shed with good power supply and looked after - most likely moved very little

6. Purity of DC in the arc - Inverters have a cleaner DC as it has a 25Khz+ of ripple as opposed to Transformer machines with 50Hz ripple however you can add capacitors to a transformer machine to clean up the DC component.

I presume a cleaner arc would be easier to use? if so that is a plus for a beginner

7. The torch - The torch has a duty cycle also and is generally less than the machine. With gas shielded welding you get some cooling however with flux cored wire you will need to increase the torch head to accomodate this or else provide alternate cooling.

Ability to upgrade to a better torch would be a plus if it ever became a problem

My biggest concern is buying something that should do the job but lets me down.

eg your 200amp Inverter Mig is very tempting eg lots of features and a good price but being cheaper makes me think it might be inferior to some others (although it might not be!)

I just really dont want to end up with a machine that is nothing but a headache

Them Cigweld 175 transmigs are a pretty good machine as you can also use them for tig and stick welding and they are pretty good on steel up to about 6mm

Hi Luke

My recommendation would be to buy a brand name... Cant go wrong with WIA, lincoln, Kemppi or just about any of the others...Havent had may people complain that they bought the wrong machine... Workshop welder i would go with the new WIA 190 with a trolley should be able to get one of those for around a grand and go in to the draw to win a car this month!! lol... Great warranty on these too.... but just my opinion. Great low down and heaps of grunt... Also just because it say 200 amps on the box doesnt mean it is... I have a 200 amp migomag (wouldnt really recommend ) and my uncles WIA 150 has more grunt than mine does so???

Hope that helps

Cheers

I also have a WIA 150 and can recommend it. Haven't used it on thin car body material but it has welded heaps of 1.2 upward and various other tubes and always well behaved. Mine is made in Australia, not sure about the new ones.

I have bitten the bullet lately though and running it on Gas, the result is like night and day and don't think I will ever use gasless again, I would rather stick.
Just given it a workout building my new welding table which has some 10mm plate on top and some of the structure and it coped well with some fairly heavy welding with no worries at about 30 degrees ambient.

Looking to upgrade to something that can handle an Ally boat building project later in the year, but I think I will keep the little WIA setup for steel work. It would be a pain changing back and forth.

I am still doing the research on the Ally machine??? Like you lots of questions and everyone has a slightly different idea, but I have found a lot of helpful info from knowlegable people here and it all helps.

How well do the combo machines do TIG?

Would i be crazy to consider TIG over mig?

Originally Posted by mac_man_luke

How well do the combo machines do TIG?

Would i be crazy to consider TIG over mig?

From what I have seen, many of the combo MIG/Stick/TIG machines only have basic TIG function with scratch start DC only, but no doubt would be useful but not as comprehensive as a dedicated TIG.

I bought a dedicated TIG so I had Ally AC capability, HF start, Pulse etc which is not practcal in the above setups.

If you end up deciding on an inverter Mig, many come with DC Scratch start TIG capability anyway so you can always play around with it and it should be fine for steel work either way.

It would be nice just to have one of everything....

my latest thoughts are to buy a WIA 190 mig, get used to it etc

In say a year buy an AC/DC tig and then learn that

Hey all

In my opinion combo machines do everything ok.....not well. Far better off to buy dedicated a machines for each process and these ac/dc, mma, plasma cutter, coffee machine, garden edger......etc combos that do everything...well lets just say the ones i've seen (all chinese) do everything...really badly. There are combo machines that i would recommend but lets just say they are out of reach for the common hobby/handy man (ie fronius TPS machines). Dont think you'll regret the WIA mate, they just have sweet arc properties...smooth as silk...if you use good wire too. Buy brand name wire (cigweld lw1-6, hyundai 70s-6 (great wire), wia austmig es6 for example) too no ebay junk as wire is not very expensive really, $35-40 a roll, and lasts a long time. Keep it dry, rust free and your welding will be a pleasure not a pain.....

Cheers

Hi All,

A combo machine employs high current - low voltage for TIG and Stick welding or high voltage - low current for plasma cutting. The transformers in the inverter machines are either parallel / series via a contactor or twin winding with selection via a contactor. The reason you can combo them is that TIG, Stick and Plasma all need a constant current power source. It is not magic, it is not voodoo. It is elementary electrical principle. 200 amp TIG @25V arc voltage = 5 kilowats / 40 amp plasma @125 volt arc voltage is 5 kilowats. The same inverter drive is pumping out the same power for both applications and it is the transformer arrangement that is responsible for whether it is used as TIG / Stick or plasma.

Champion did make a combo in Australia many years ago but it was the size of a washing machine. It is only the inverter principle that makes it easy to manufacture in contemporary times.

In my oppinion and in my experience combo machines do things very well. Quite often it is the torch that is not suited correctly to the product or a lack of understanding how to set one up correctly. No offence to the Y genners but if it's not working for you, it could actually be you. Some research and understanding of how things work will often reveal the desired result.


John - old timer