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Posted by Private on March 22, 2008, 12:34 am
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> In my downloaded Lincoln DC welder manual, they refer to the welding
> current controls in terms I am not sure of. They say when you want a
> "buttering" arc, to set the main current step dial, then use the fine
> current at the lower settings. It says 6010 is what you want a
> "buttering" arc for.
>
> Then it says if you want a "digging" arc to do the opposite, to set the
> main current lower, then adjust the fine current to the upper settings on
> its dial.
>
> I have not heard of these terms before. The 6010 was specifically cited
> in the paragraph on buttering, but no rod was mentioned in the "digging"
> paragraph. Would the "digging" setting be for 7018 or heavy iron powder
> coating rods?
>
> I have welded for a long time, but have lost information on my grey matter
> hard drive here and there along the way. I'm having to relearn some of
> this. And then, anything you don't do for a while, you get rusty.
>
> Thanks.
>
> Steve
What is the URL of the manual you downloaded?
Your questions raise the issue of semantics as these terms are often used in
contradiction to expected usage and are also subject to varied definition
and usage. Here is some information you may find helpful, note that I make
no claim to be an electrical engineer.
Google 'drooping volt amp curve'
http://www.google.ca/search?hl=en&q=drooping+volt+amp+curve&meta=
http://www.millerwelds.com/education/articles/article108.html
http://www.welding.com/welding_terms.shtml
http://newsgroups.derkeiler.com/Archive/Sci/sci.engr.joining.welding/2006-07/msg00137.html
or Google groups
CC welding generators have a drooping volt amp curve. This means that the
voltage will vary between >60 volts OCV (open circuit volts) when not
welding, ~ 40 volts when welding and <10 volts when short circuited. The
amps will also vary with arc length, the amps will be lowest with a long arc
and highest with a short arc or short circuit.
Most motor generators have ~five (or six) sets of winding configurations (or
ranges) which are selected using the left step control dial. The right dial
is a rheostat which IIRC controls the exciter voltage and thereby the amount
of OCV and power generated in each range. If you are looking for 125 amps
you can probably get it with a low left range and a high right setting, or
with the next higher left range and a middle right setting, or the next
higher left range and a very low right dial setting. Each combination will
result in a different slope for the drooping volt amp curve and will result
in different arc characteristics as the operator varies the arc length. As
a skilful operator whips the arc of a 6010 they are lowering the amps as the
arc lengthens which allows the puddle to freeze, then shortening the arc to
raise the amps and the electrode burnoff rate as they get back into the
puddle. This technique is easier when using a flat VA slope (low OCV &
right dial) as there will be relatively more change in amperage with change
of arc length. (see figure 10-3 in following link) The combination with a
high right setting will result in a forceful or digging arc that will
increase penetration, it will also give a steep VA slope and a smaller
variation of current as the arc length is varied. The combination with a
low right dial setting will result in a soft arc that will be quieter and
less forceful. Many welders like to use a low left / high right setting for
large electrodes and welding flat fillets and a higher left / lower right
for welding vertical or overhead. A very high right dial setting will allow
6010 electrodes to be very forceful with high penetration and are sometimes
used for 'quick and (very) dirty' cutting.
Here is a link to the Army welding manual TC 9-237 (caution it is a funky
site and the pages are very slow loading, wait until done before attempting
to page down)
http://www.fortunecity.com/village/lind/247/index_WELD.htm
I suggest you read section 10-2 especially the para(2) dealing with dual
control machines, and study figure 10-3..
http://www.fortunecity.com/village/lind/247/weld_book/Ch10.htm
Get a good demo and practice lots. Good luck, YMMV
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