Wire speed?

[clevinski]

Hi...

I'm a beginner and have gotten some excellent advice here over the last month or two. I've read a lot of posts and some of the excellent documentation and tutorials on the site, and it seems clear that faster wire speed is generally needed when using higher current. In some of what I've read, it stated that faster wire speed equates to more heat. But I am having trouble with one issue.

When trying to improve penetration by welding more slowly, should I use faster or slower wire speed? When I tried to use faster speed yesterday, I started out with a good puddle but it soon built up to an excessive height. I wasn't trying to get a higher weld, but better penetration.

So what's the consensus? All other things being equal, faster or slower wire speed when trying to weld more slowly for better penetration?

 

[Rusty]

Hi clevinski,MIG welding is a fine balance of power,wire speed,welding speed,and ability. If your welding thin material ( 1mm ) and you go too slow your likely to blow holes so just practice and adjust power/wire speed until you achieve the weld you are aiming for,thicker material is a lot more forgiving and is easier to master the ' art '

 

[irondarren]

wire speed is very much set by the output voltage of the machine, the higher the voltage the more wire speed. if the wire speed is to high, it doesnt melt properly and will leave cold edges, resulting in a bad weld. You can only slow down the travel speed to a certain degree to increase penetration after that as you noticed it just builds up the weld. what are you trying to weld and with what power output, it could be you need to turn it up a power setting

 

[clevinski]

Thanks for the comments, guys...

Regarding what I'm trying to weld, after a month or two of test welds, I decided to actually make something useful. My new bench grinder has a fine and coarse wheel. The coarse wheel has a flat rest in front of it, but the fine wheel has a rest with a groove in it for sharpening drill bits, which I'll likely never use. So I wanted to make a replacement rest without the groove.

The longest dimension of the rest is perhaps 3 inches (75 mm). I took a small piece of angle iron .187 inches (4.75 mm) thick, cut it to the shape I wanted, and then needed to weld an end piece on it to mount it. (Please see the photo of the original and replacement rests below.) The piece I needed to add is the side with the hole in it in the original rest.

The welder I am using is an older, small Dayton 85 amp max. model. I have the welder on the highest current setting (4). To get better penetration, I ground a V into the edge of the flat plate approx. 2/3 of the way down, leaving a face of about 1.6 mm thickness. I tried to weld as slowly as possible, but as you say, Irondarren, I quickly had an excessive build up of material. The original weld looked pretty good, so I think the part is OK (I'll find out tomorrow when I start beating on it with a sledge hammer). I then welded the outside edge, which I hadn't originally planned to do. This edge had no V but the penetration was pretty good and the weld looked (to my untrained eye) to be pretty solid. Unfortunately, I ground this outside weld down before the photos were taken. (This weld is shown in the last two photos.)

So, if I understand correctly, there is a relatively narrow band of wire speeds that will work properly for a given power setting/weld speed/material thickness. One can adjust the wire speed towards the lower end of this narrow range to weld a little slower and get better penetration, but the range is not very wide. Is this correct?

Many thanks for everyone's comments. I appreciate the very helpful attitude of everyone on the site.

 

[AusWeld]

Hey im not really experienced but from what i know if the welder is just an 80amp jobby i dont think it wond be powerfull enough to do almost 5mm steel read the tutorial section its got a calculator which will give you a good indication on what your welder is capable of

 

[clevinski]

Hi, AusWeld,

Thanks for the comment. Yes, I had checked this calculator out and was aware of it. If you grind a V-shape into the edge, though, you can weld material about 25% - 33% thicker.

At any rate, I have been running the welder on an extension cord until I could install a dedicated 20 amp breaker. I installed one over the holiday and tried it today. What a difference! On the maximum setting, I was going a bit too slow at the maximum 85 amp setting and it burned through the 5 mm material. So a big part of the problem seems to have been the extension cord limiting the current flow.

 

[irondarren]

on an extension cable you will get to much voltage drop and hence not full power from the machine