Dig or Arc Force

By Lawrence (*****)

Date 05-21-2009 22:20

Hey Hawk,

Arc force helps add a little voltage to the arc when the electrode becomes close to or touches the work.

Generally.. High numbers on arc force are used for open roots; for example with 6010 and an open root the electrode goes right into the arc gap to form the keyhole.. If the electrode tends to snuff out, an increase in arc force will raise the working voltage for a short period and keep the arc ignited.

Usually the low-hi rods tend to produce more spatter than is tollerable with high dig settings... I normally run 0-3 when running E7018 unless I'm running extra low current for that rod diameter and am having sticking problems..

Anyhow.. Thats the nutshell version.... But if a higher number makes your low-hi work... There is not a thing wrong with doing what your doing.

By aevald

Date 05-22-2009 00:52

Hello Hawk, read your post here and Lawrences response. Did a little checking around and found this rather interesting article on Miller's site, thought you might enjoy it. Best regards, Allan

Attachment: UnderstandingaWeldersPersonalityVoltAmp.mht (394k)

By 357max

Date 05-22-2009 14:06

Amperage effects (has the greatest affect on) penetration/voltage controls (has the greatest affect on) the height and width of the weld pool/deposit. SMAW requires a constant amperage output. Increase amperage increase penetration conversly decrease amperage decrease penetration. SMAW's "arc force/arc control/dig' circuiting provides an increase in amperage/penetration with a decrease in voltage usually 19-21 volts. This is electronically controlled at speeds of a microsecond or faster. Most SMAW arcs will be 25 - 40 volts so there will be no additional amperage from the "dig" circuit. Shorten the arc length and the voltage drops below the machine manufacturer's "trigger voltage" and the "dig" circuit turns on. As soon as a normal arc length occurs the "dig" circuit turns off.
Starting first; set the with the "dig" at "0". Then set machine's amperage for desired/preferred weld pool and arc's control. Then adjust the "dig" control until "HAPPY"! Remember, the heat input is calculated with measured volts, amps and travel speed any extra control adjustment is just that - extra.
On a CC/CV machine the "arc control" becomes an inductance control when the machine is set to the CV mode.

By reddoggoose (**)

Date 05-22-2009 15:24 Edited 05-22-2009 15:27

When welding SMAW with a Miller machine, the dig becomes active at about 19 volts. What this does is as the voltage drops or arc length decreases to below 19V, current will increase. This increase in current will act to clear the short (low voltage). Higher dig values are typically used on XX10 electrodes which are rods that typically have a "stiff" arc, especially when welding downhill on an open root joint, which will help push the bead into the root and minimize the rod sticking. When running a 7018, a lower dig value is usually preferred. This is because a 7018 typically transfers across the arc in a globular transfer. If those globs hang off the end of the rod and touch the plate voltage drops (short). The dig will increase to the needed amount to clear the short. Large short clearing currents will cause the short to clear, but will be at a high current which will cause large spatter (unloading). Low dig settings limit the amount of current available to clear the short, resulting in a cleaner separation of filler material and a softer arc. An easy test is to run a 1/8 7018 on a flat clean plate with dig set in Minimum. Repeat the test on another clearn plate with the dig set to Maximum. On the Max setting you will notice large spatter pop out of the puddle, this is the unloading from to much short clearing current. By knowing how dig works you can tell how well a particular machine will run a given rod by looking at the Volt/Amp curve for the machine, before you even pick up the stinger.