Arc Welding

Arc Welding – Tips and Tricks

When you are arc welding, or any form of welding, always wear proper protective clothing. Arc rays will burn your skin and the damage you sustain is going to be compounded in time. Skin cancers are a common, long term problem with people who don’t wear long sleeves. A good helmet, gloves, boots and long clothing should always be worn. Slag or molten metal burns are deep tissue burns which can lead to infection and scarring not to mention they bloody HURT!!!!  Try not to even tack stuff together without wearing a helmet.  You only get one set of eyes…..look after them!

In each of these seArc Weldinggments, the first thing I will be doing is clearing up a few definitions that people commonly use because it makes our job here at IBS and in all other welding supply shops a lot easier if we are all talking the same language.

Firstly, Arc Welding is known by a couple of other names. Stick welding being the most common and MMA (Manual Metal Arc) being the most technical. I’ve always referred to it as Arc Welding which is actually quite wrong and right at the same time. Think about it for a second……ALL forms of welding rely on an arc of some description.

Check you have a good earth before you start!

There are quite a lot of different electrodes for different applications and I’m not going to try to confuse everyone by going into the technical specs of every electrode out there! Let’s just say there are electrodes that have a multi purpose and ones that have a specific purpose and it’s up to you, the end user, to make sure you get the right ones for the job and it’s equally up to us as the suppliers to give you the right information.

Realistically, the only thing the average person needs to know is will the electrode do the job and has your machine got enough power to run the electrode size you are using. For example, you can’t run a 4mm electrode on a 130Amp machine nor can you successfully weld cast iron with a GP (General Purpose) electrode.

So how do you know what electrode to use? Ask your mate who is a boiler maker, ask someone in a shop who actually knows or is not scared to admit he doesn’t but finds out for you or Google it. Google is a good source and there is an American website which has videos on welding techniques etc, but the guy does get a bit technical at times.

Arc WeldingThere are a few different brands of electrodes which I can’t name for legal reasons and a lot of cheap ones made overseas. The cheap ones can be very much hit and miss when it comes to metallurgy and ease of operation. They may work fine and lay down a good weld or the same brand, size and type may as well be used as tent pegs. It’s a bit of a gamble.

My preference in electrodes is the ones in the yellow and blue packets for ease of use and performance (no names mentioned).

So we now have the right electrode to do the job. Check the labelling on the packet for amperage and use this as a rough guide because it depends on the power going into the welder as to what power comes out. Running on an extension cord can drop the output power dramatically. Keep any leads as short as possible and make sure they have the right power rating.

Strike the arc and away you go…..maybe. Some electrodes can be a pain to get started and sometimes giving them a couple of quick drags on a scrap piece of metal make them easier to get arc up. If you have an electrode stick to the job, check the flux around the tip. It will quite often break off making it exceptionally hard to get started. Sticking electrodes can be from not enough power, bad earth, dirty material or just the fact that the electrode you are using is a pig to get started.

Arc WeldingWhen you get your weld pool going, what you see through your helmet is not what your weld is going to look like. There is molten metal and flux which gives the impression of a nice weld but it’s when you chip the slag off, that’s when you see what is really there. “Bird sh*t” results are usually from trying to travel too quickly and big, lumpy welds are too slow. Practice will find an even medium and a small, circular or backwards and forward motion with the tip of the electrode can help it fill and lay down a very nice weld. Generally, holding the tip of the electrode off the job by about 2mm after starting the arc works fine and will usually lay down a pretty good weld. Practice is the best teacher.

Always drag your electrode. The mechanics of dragging pushes the flux away from the weld pool allowing it to solidify on top of the weld, keeping oxygen out. Pushing an electrode can cause the flux to become included in the weld and weaken it. That’s also why you always chip and if necessary use a wire brush on a weld before trying to lay down another one on top or beside it.

Check that you have good penetration on your weld. Not enough penetration will cause the weld material to sit on top and not melt into the job which will give you a very weak joint. There’s usually a heat mark on the backside of the welded job which is a good indicator of reasonable penetration. Too much power can cause the weld to “burn through” or change the structure of the metal causing it to crystallize and weaken. Unless you know your welding parameters, set your welder up on a scrap piece of metal about the same thickness as your job.

Avoid cooling the job under water immediately after welding as it can cause the weld to crack or weaken the parent metal around the welded area causing it to fail.

Finally, chip away any slag left on the weld. A lot of good quality electrodes will have the flux peel up behind you if everything is set right. Wire brush the weld if it needs it but always try to remove as much residue as possible. Then when it cools down enough, give it a coat of metal primer or spray gal.

Remember to protect yourself from accidental burns and NEVER weld on wet floors, in wet clothes or in any wet area.

Stay safe.


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