PDA

View Full Version : Add a fan to an arc welder



Stirfie
21st Aug 2005, 11:28 PM
HI
I just bought my first arc welder. I have been doing some practicing over the weekend. I found out that my welder only has a 10% duty cycle at 60A. I don't intend to do a lot of work with it, but thought if I added a fan to it I could get more up time with it.
If I add the fan would it need to be blowing into the welder, or out of the welder (extracting air).

I am a sparky and understand the normal saftey issues.

Regards
Paul

Mick C.
22nd Aug 2005, 08:48 AM
The mig welders that i have seen, as well as my own WIA, all have the fan blowing into the cabinet, and usually onto the transformer or rectifier, as these are the only areas that get hot and will be the area that is duty cycle rated. Also as far as cooling is concerned, the greater the pressure differential across the item being cooled, ie- the transformer, rectifier, or heatsink, the greatest cooling, is with the fan blowing into the item to be cooled, rather than just displacing the air around the item or sucking accross or through the item. There are formula to be found about this, but we did a mock setup at work for cooling a high powered FM Radio transmitter, and the cooling effect is a LOT more than just a few deg C, i think we came up with a figure of about 20% cooler just by turning the fan around.

Grahame Collins
22nd Aug 2005, 06:46 PM
Stirfie,
Hi,
I look at the figure of 10% duty cycle and say why bother?
Bloody hell mate Most figures I can recall at the very worst go from 20-25 % duty cycle. As the work value increases ( the higher amp load ) the duty cycle decreases )

You have got a welder capable of working at ony 10% of the time and the only at 60 amps. What do you intend to weld ? If the figures you have supplied are correct do not bother with the fan.Take the welder and soak it - IN DEEP WATER.
Honestly the money you save even on the fan could be put to a good little unit even a liitle GMC stick welder that will give much better efficiencty for infrequent use.
If you are going into some major projects grab something like a Flowarc welder

These units are top shelf and Aussie made to boot.OK they are around $400/$500 dollar mark but ya gets what ya pays for. Four copper coils, protected infinately adjustable operating controls , high low /voltage connections, steel ball bearing rubber coated wheels etc.

Other wise it just cheaper to hire welder if your not welding often.

My two bobs worth.
Grahame

echnidna
22nd Aug 2005, 06:50 PM
Put a kitchen exhaust fan on so it blows through the machine, will help duty cycle but you're a sparks and already know that.

Stirfie
22nd Aug 2005, 10:04 PM
Thanks for all your replies. I bought the welder from repco, just a $99 job. I mainly got it to learn on. If I ever do any heavy duty stuff, I will hire one (thanks Graham). I have bought a 12cm fan from dick smiths for $30, I have installed it and will see how it goes.

Regards
Paul

Stirfie
12th Sep 2005, 10:34 PM
just to let people know, I added the fan and I now have lots more uptime with the welder.

knucklehead
12th Sep 2005, 10:45 PM
HI
If I add the fan would it need to be blowing into the welder, or out of the welder (extracting air).


When you try and cool something like this the air should be drawn through the coils. The air needs to be directed through the coils (elliminate as large leaks)and the hot air exhuasted out. Blowing air on to the coils is much less effective, it just circulates already hot air.

I added on of these fans to my cheap welder and improved it no end. Mine is wired so that when ever there is power to the unit the fan is on. This means when you get a thermal shut down the fan will still be running and the reset time is much reduced.

Stirfie
12th Sep 2005, 11:01 PM
Hi, I mounted the fan at the back, drawing air in through the rear vent, and the hot air is expelled through the sides. I also wired mine so that the fan is on when the welder is plugged in. Even when the thermal overload cuts out, it takes much less time to come back on again.

Mick C.
12th Sep 2005, 11:09 PM
My WIA machine has the factory fan fitted to blow air into the machine to aid in cooling. The greatest cooling effect is when you have the greatest pressure differential across the item to be cooled and this only happens when the fan is blowing onto the item to be cooled. If the air flow is set up correctly in the machine, it will displace all the air in the machine rather than move it around.