2 second welds :(

JamesJones · Apr 25, 2012

Hi everyone,

I've had some welding experience (about 3 months work in a shipyard )before but it's been about 4 years since I last welded.

I just bought a Silverline 160A 466888, I'm using 2.5mm 6013 filarc rods and a current of 60-90A. I've been testin it out on some 3mm box section scrap trying to get a good seam but every time I get one going it cuts out after 2 seconds, which means that I can never get into a groove. It's very frustrating.

It's hooked up to a standard socket with a 13A fuse.

Is there something wrong with the machine or is this model only for spot welds or something !?

Wozzaaah · Apr 25, 2012

What cuts out?
Does the arc stop? Does the breaker pop? Do you have to do anything in order to restart the machine?
More details please.

rich r · Apr 25, 2012

You certainly shouldn't have any problems with 2.5mm rods on a standard 13A plug. Around 115A of welding current is the limit for most welders before blowing the fuse.

As above, what's actually cutting out? Something on the welder? The fuse in the plug? The circuit breaker on the supply?

The Silverline 466888 looks almost identical to the £35 Aldi one I've got, even down to the colour of the paint. I can certainly use up a full 350mm 2.5mm rod in one go without even tripping the thermal cutout on the welder.

JamesJones · Apr 25, 2012

Thanks so much for the quick response guys the arc just dies. The machine doesn't cut out or turn off.

http://www.youtube.com/watch?v=kUzAuL7gN6I&feature=youtube_gdata_player

Here's a video (WFS) because I'm not terribly gifted in the art of description. Hope it helps.

James

awemawson · Apr 25, 2012

Bad welding earth return?

Paul. · Apr 25, 2012

What type of electrodes are you using, most small transformer welders or buzzboxes have a low open circuit voltage (around 50v) and will struggle to run anything other than a 6013 electrode.

PTvor · Apr 25, 2012

Have you looked up the spec sheet for these filarc rods on the web or looked for the OCV on the packet?

If they need an OCV of over 50V, they won't work very well on a buzz box with an OCV of 50V.

A lot of rods say on the packet something like "recommended for use with light transformer welders" or similar.

JamesJones · Apr 25, 2012

Closer inspection reveals that I'm using Filarc 56S MMA Welding Electrode. Here's the link http://www.metals4u.co.uk/detail.asp?cat_id=162&prd_id=2925 (WFS)

are these pretty lousy electrodes? and could this be causing the problem ?

James

rich r · Apr 25, 2012

Silverline 160A has an OCV of 48V for reference.

There are several grades of Filarc E6013 rods, some of which require an OCV of 60V or more, so that could well be it.

As an aside though, surely once the arc has been struck, it's no longer open-circuit?

PTvor · Apr 25, 2012

These are a low hydrogen 7016 rod and need an OCV of 65V.

http://products.esab.com/Templates/T041.asp?id=58372

I doubt that they are lousy rods, it's just that they are not going to work with a little air cooled transformer welder like yours. They need an inverter or a transformer welder which can produce a high OCV.

I think you'd be better off with these from the same place. Much cheaper per rod too.

http://www.metals4u.co.uk/detail.asp?cat_id=152&prd_id=2896

JamesJones · Apr 25, 2012

Thanks so much for your help, I'll get some new rods and tell you how it goes.

I'll post pic of my project as well once I'm done if you're interested.

PTvor · Apr 25, 2012

rich r said:
As an aside though, surely once the arc has been struck, it's no longer open-circuit?

But since it's AC, swapping from +ve to -ve and back 50 times a second, it goes out 100 times a second and there's the problem.

The rod has to cope with a very warm strike many times a second.

However a DC welding source doesn't have that problem. Inverters are a pulse of DC thousands of times a second but the going out of the arc takes time, and if you are talking about the current being cut off thousands of times a second the arc doesn't really die at all in that short a time.

I really don't understand why inverters often have problems with celluosic rods.

No doubt TechnicAl could shed some light on this.

shenion · Apr 26, 2012

It is not just that the arc start/stops but also arc stability.

As an example my alternator welder worked fine with DC with a 70V OCV. I added filtering caps (60,000uf.) Then the arc would sometimes just go out.

Turns out the reactor (choke) was not enough to maintain the arc. At times the arc resistance would increase and with the caps, it could not raise the voltage fast enough to compensate even with electronic current control.

Some rods would work fine (7014) while most would just go out unless you upped the current.

I reduced the caps to 4,700uf and now it works perfectly.

Arc welders are supposed to be constant-current. SO they need to change voltage continuously to maintain that current. Low OCV welders don't have the range to maintain constant arc.

rich r · Apr 26, 2012

That makes sense to me. My degree is in electronics, but more specifically signal processing - high current and voltage are things I don't know the subtleties of

I guess 'softer' rods maintain an arc more easily (for various reasons, but effectively there's more in the way of ionised gas between the rod and the workpiece, so lower impedance) and as such the current flow is more continuous (be it ac or dc) - and hence the voltage is also more constant, so more likely to be kept regulated well.

PTvor · Apr 26, 2012

DC rods have sodium silicate and the AC versions have potassium silicate because potassium is more easily ionised. (6012 vs 6013)

However, as you say, there seem to be a lot of subleties.

JamesJones · Apr 28, 2012

I've got the new electrodes and it works! I'm getting some really good seams. I'll post pics of the project.

Again, thanks for the help.

2 second welds :(

JamesJones

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