High or Low Inductance?

Date 05-20-2009 15:56

Kurt,

The highest probability is that someone is playing you. Is he an older welder? Older machines for power sources had variable 'induction' settings to tweek the arc. Worked along with 'Slope' settings.

Most welders didn't have a clue as to how they worked and only messed things up by playing with them.

Most of the machines today do these automatically. Only difference in settings is a high and low range to go from short circuit transfer, your setting, to spray transfer. Only changes the volts/amps of the welding, does not let you adjust the slope or induction.

I don't know much about the Deltawelds. Hopefully someone else will chime in here with more info. Also, it does seem like Miller and Lincoln are putting more and more controls on machines again. Some of them you feel like you have to be an Electrical Engineer to run or at least adjust the things. Being able to change things can be good if the personnel running it knows what they are doing, not just guessing.

Have a Great Day, Brent

By Lawrence (*****)

Date 05-20-2009 15:59

Hey Kurt

I'm sure this will turn into a long thread with lots of responses.

But for the purposes of GMAW we need to start with understanding of what inductance is... What slope is.. and how they can effect GMAW.

It sounds like your deltawelds have two seperate "slope" terminals or taps. One flat and one steep.

If your machine has two taps... The Flat slope tap is desirable for Spray Transfer GMAW and FCAW... The Steep slope tap provides better short circuiting performance.

Inductance is another type of control that has a greater effect on the rate of current change... Inductance controls are most valuable in GMAW short circuiting transfer mode... The inductance is generally a 1-10 setting on a knob or touch pad. The lower the setting the greater frequency of short circuits. The higher the inductance setting the lower the frequency of short cirucits. A high inductance number is preferable for open roots where full penetration welded from one side is required.. A low inductance number may be suitable for very thin material where burnthrough is being avoided... a middle type setting is where folks generally start and then adjust according to working requirements.

By CHGuilford (****)

Date 05-20-2009 16:06

Ow. My head is hurting already.

:)

By welderbrent (*****)

Date 05-20-2009 16:32

Lawrence,

Thanks for that information. I have an old Linde machine that we use for FCAW-G that has slope and induction settings. I am always having to grab books and refresh my memory on how things work. Your answer gives a very good, brief description of the process.

Do many machines still use this, or is my interpretation right that most have gotten away from these settings and the machine adjusts reasonably well automatically?

Have a Great Day, Brent

By Lawrence (*****)

Date 05-20-2009 16:58

Brent

There is a variety of stuff out there on the market today.

All my new inverter power supplies... Miller Axcess, Miller 350P, Lincoln Powerwave, Miller XMT, All have inductance controls... Some controls are harder to get at than others (requiring combination touchpad stuff)
The only time I have made any adjustment to the factory settings is when open roots welded from one side come into play.

I also have some new Miller CP 302's... These have no inductance control and no multi-tap slope choices... However they are awsome GMAW/FCAW power supplies... Simple as can be.. One crank for voltage and one knob for wire feed speed on the feeder... Nothing else! With our dual feeders we can run short circuit open roots with 100% C02 than just grab the other gun and run gas shielded FCAW covers with only a quick crank on the voltage and a twist on the knob for wire feed. Really like them alot. The slope and inductance on these machines are factory set and work so well I haven't even looked into the possibility that changes could be made under the hood.

We have some old Miller Demension CC/CV power supplies, and inductance controls on those are pretty valuable for open roots or very thin stuff.

We also have a pretty old Miller CP200 that has dual slope taps... And it works quite well even after 25 years of student abuse.

By welderbrent (*****)

Date 05-20-2009 17:44

Thanks Lawrence,

Yes, our old Linde still performs very well also. It has seen a lot of abuse. Other than it, I haven't seen welders with these settings on them since the late 70's. Everything I have used and shops I have been in for inspections have been equipment that is factory set. No external adjustments for slope or induction. Wasn't sure rather there were many made that had that option. I guess I don't go through Lincoln and Miller catalogs often enough with an eye to all the different features on the machines.

Kurt, hope you are getting all the information you need with your original question. Hope I didn't muddy things up.

Have a Great Day, Brent

By SWP

Date 05-20-2009 16:18 Edited 05-20-2009 16:22

Here is a link to basic info on slope and inductance from ESAB. http://www.esabna.com/EUWeb/MIG_handbook/592mig3_6.htm
As I understand it, high inductance reduces the number of short circuits per second, increases puddle fluidity, and reduces spatter. Excess inductance can cause arc starting problems.
I've seen it written that inductance is most significant in short arc transfer, but I have seen positive effects in pulsed spray transfer.
Back in 1983, while working in the weld lab at Dimetrics, a Pow Con engineer helped us design a suitable inductor to add to the new Metal Beam pulsed mig power supply. We first experimented by simply coiling several wraps of the work cable around a chunk of steel and this had the effect of improving arc stability and reduced spatter at lower voltage settings. The power source engineers then produced a small coil that was added into the power supply.

By Kurt Miller Date 05-20-2009 18:15

Thanks for all the replies. I enjoy digression in topics. I tend to learn more that way.

We run fairly new Miller Deltaweld 452 CV machines. There is no knob, just two taps, one says high and one says low.

Your description and post have been very helpful. We also use the dual feeders and run FCAW on one spool and bare wire on the other. Until now, the welders have never changed this setting, always leaving the EP tap on high inductance. From what I understand from the posts, the welders should consider switching to Low or "flat slope" inductance if they are primarily running FCAW. (Which 90% of our work is FCAW)

We had some trouble passing PQR test for open root with both an 80 and 90 series wire @GMAW-s. I wonder if this would have helped.

By 357max

Date 05-22-2009 14:39

Inductance controls on the constant voltage output welding machines are a fine tuning control of the arc. A constant voltage welding output machine provides a voltage control therefore the voltage remains relatively constant. Voltage controls the height and width of the weld deposit. Wire feed speed determines the amperage the machine provides. Amperage most effects the penetration. Setting the voltage; the welding machine will provide the amperage needed to clear the short circuit of a gmaw weld. How fast the machine reaches the amperage is the function of induction.
The high and low taps/output studs on the deltaweld machines are now identified as - high - stainless and aluminum or low - all other metals. High inductance works especially well on short circuit transfer it keeps the arc on longer to wet out and flow the weld pool. Especially helpful with stainless steel scmt. When welding aluminum with spray transfer; the arc starting is when the short circuit occurs and with high inductance there is a slowing of the machines response to reaching the amperage to clear the short circuit. It minimizes or possibly eliminates the burn back to the contact tube at arc starting. High inductance may cause stumbling/sputtering starts with fcaw or carbon steel spray transfer.
Slope adjustment is available on older cv - constant voltage/cp - constant potential welding machines like Millers CP250T or CP252T. The "T" stands for tap slope. Slope limits the amount of amperage/current to melt or clear the short circuit. For example-some text/authors state a solid E70S electrode of 0.035" diameter wire needs about 350 amps to clear the short circuit. With "0" slope the machine could reach out for well over 1000 amps to clear the short circuit. Adding turns or taps of slope limits the short circuit amperage. Moving the taps closer to the amperage actually needed to clear the short circuit minimizes the spatter created when scmt. Inductance than may be used to further "smooth" the arc if a machine has both slope and inductance control. Miller's old MC300VS was such a machine. I believe there are no constant voltage output machines manufactured today that has slope control; only inductance control - either a set value of high or low or a variable control.