4 Problems with Fume Extraction MIG Guns (and How to Overcome Them)

Posted by Etienne Blouin on Dec 29, 2017 8:26:00 AM
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We get it, not everyone loves fume extraction torches. For one reason of another, whether you're a welder or a welding engineer or a project manager, the same problems or complaints come up when it comes to fume guns.

Well, we're here to say that yes, fume guns have had problems - and some still do. But maybe it's not the gun you're using that's a problem, but simply the wrong manufacturer. Or, old notions of fume guns - the ones that were true across the welding industry 10 years ago - have you hung up at looking at fume torches again.

We're going to dive into those top problems you'll always hear regarding fume extraction guns and put an answer to overcoming those problems:

  1. Fume Extraction Guns Are Heavy

  2. Fume Extraction Guns Make Accessing the Weld Difficult

  3. Extraction Guns Don't Collect as Much Smoke as Advertised

  4. Fume Extraction Guns Cause Porosity and Poor Weld Quality

And we'll explain were these problems come from, how they've been addressed in recent years and new version of fume extraction guns, and how they perform and compare in today's welding environment.

1. Fume Extraction Guns Are Heavy

This is a problem of bad first impressions and past experiences. All welders - and rightfully so - will tell anybody that puts a heavy gun into their hand that it's too much weight and they're not going to use it. And it's a valid concern, especially when it comes to fume extraction guns. Some can be extremely heavy.

But not all welding fume guns are the same. Fume extraction guns have come a long way since their earlier, bulkier, less comfortable ancestors. Today, with an increased focus on ergonomics and making the cable & fume hose more maneuverable, many of today's fume guns are going to weigh as much if not less than comparable air-cooled guns, and be more comfortable in the hand.

Don't believe it? Take a smoke extraction gun built more recently - especially one that has a focus on ergonomics and comfort - and hold it in one hand with your normal air-cooled gun in the other. Or better yet, just weight it on a scale. You'd be surprised just how light today's fume guns are in comparison to their standard air-cooled rivals. A lot of standard, 400 amp air-cooled guns will actually be heavier in weight than a similarly rated fume gun depending on the manufacturer.

Also be sure to check the welding torch specifications that matter when it comes to comfort - how much trigger pressure is needed to strike the arc, the diameter of the handle, the angle of the torch, and how much range of motion on the wrist the welder is able to have while handling the welding torch.

2. Fume Extraction Guns Make Accessing the Weld Joint Difficult

Welding fume extraction guns are bulky at the front end for the most part. Torch makers  at the beginning of making fume guns were so determined to get that shroud to collect enough welding fumes to be effective while also designing a nozzle that can accommodate such a shroud. The result was that welding torch makers almost universally made the front ends on fume guns so big and bulky welders couldn't access the weld joints they needed or  worse, couldn't see what they were welding. The problem originated from makers not using standard-type welding nozzles, and welders hated them. It's still a problem today with some current fume gun makers on the market.

Luckily, there are welding gun makers out there who have put forth improvements to their fume guns to overcome these very common complaints from welders and engineers. Today, you can find a lot of fume guns now featuring regular sized, threaded nozzles on their front end. They are the same length, some bore size, and feature same tapered style construction as other non-specialty MIG guns in use today.

This great video from Weld.com breaks down both the weld access and fume extraction gun weight myth very well:

3. Fume Extraction Guns Don't Collect as Much Smoke as Advertised

This is almost always a multi-fold issue, but the problem hits right to the promise of what fume guns are supposed to provide. If the torch won't collect weld smoke, what's the point of using it? It's a valid problem, and one that happens to welding operations both large and small.

There are multiple ways to try and overcome this problem. Some of the stigma of fume guns not even collecting smoke can be as simple a problem and solution as you're not using a good fume gun. There are a lot of design quirks to fume guns that can be pointed to:  small shroud openings, too much restriction in the hose, small hose sizes affecting air flow, or the shroud being too close to the arc. All of these can adversely affect how well your fume gun collects smoke depending on the gun parameters and the fume extraction unit in question.

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Another cause of the torch not collection smoke is needing to match the vacuum suction strength to the welding parameter. It's important to make sure a hi-vacuum system is being used with a smoke gun, and that the CFM (cubic feet per minute) settings of the collection unit match the specification of the smoke gun.

If it's neither the gun nor the fume extraction system, if could also be the welder position being incorrect and having to be adjusted. If your fume extraction torch isn't collecting smoke in the way it should be, look at all the different variables that could be keeping the torch from collecting smoke until you're left with nothing but to point to the gun. 

4. Fume Extraction Guns Cause Porosity and Poor Weld Quality

Porosity is a common weld quality problem in general, but with fume extraction torches it can be more prevalent. Especially with older fume guns, whose design didn't always take into account the dissipation of gas and how fume extraction torches effects gas flow.

The problem usually is due to the fume shroud being positioned too close to the weld joint and suctioning shielding gas. This creates poor gas flow from the nozzle to the weld, and results in porosity.

Generally, better control of the process in keeping shielding gas from being extracted will overcome weld quality issues.

One way to check against this problem is using a portable gas flow meter to check the gas flow while the vacuum system is on to make sure you have the proper gas flow coming from your nozzle based on amperage, voltage, and your welding procedures. If you're using a fume extraction gun where the shroud is especially close to the welding process, this is an especially important step to check at all times.

Surely, there are other problems you may encounter with fume extraction welding torches. But in my experience, these are the most common ones I come across. If you encounter any of these problems yourself, take a look at some of the other options around.


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Topics: Fume Extraction