Piet van der Horst

Piet van der Horst

In 1970 Piet made welding his trade en since then he never stopped learning about that trade. By now he is well past his retirement age, but not welding is still not an option for him. It is not just work, it is a passion.

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Gases for welding processes

Inert and active gases

Classification according to the standard In NEN-EN-ISO 14175 standard, gases are divided into main and subgroups. In this article we discuss four main groups of

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When conviction gets in the way

We’ve always done it this way!

During question time at a lecture on MIG-MAG welding that I gave, someone asked me “Is it normal that my welders use a 1.2 mm contact tip for welding of 1.0 mm wire?” My answer was short: “No, that is not normal nor desirable.”

A closer look

After the lecture, the man asked if we could make an appointment to take a closer look at things at his company. It turns out to be a construction company where only steel is welded. There are over 40 permanent welders and occasionally, a number of temporary welders. They work on commission, so their projects are diverse and vary from bridges to halls to works of art. Sometimes there is serial work too. There is no robot or other welding automation (yet).

After a brief conversation at the office, we decided to visit a number of welders in the workshop, to see what they are doing and ask a few questions. I was curious to what extent they were aware of all the ins and outs of welding technology and MIG-MAG welding in particular. I was particularly interested in the following: 

How do the welders deal with the contact tip?
How do the welders deal with the liner?What is the pressure on the wire feed rollers?
How is the gas nozzle handled?
What are the welding parameters and are they correct for the piece that is welded?
How are gas settings handled?
And of course; why is the 1.2 mm contact tip used for 1.0 mm wire?
In the workshop, you learn the most

Of the 33 welders present, there were 3 who tighten the contact tip with a designated wrench during assembly. One welder used the side cutter for this!

None of the welders knew how to replace a liner or why you have to replace it and they did not know that there are multiple types and dimensions.

The pressure on the wire feed rollers is maximum for most welders. The reason for this is that with a wire feed failure the pressure is always slightly increased, instead of looking for and solving the real problem.

With 29 welders the contact tip was not in the middle of the gas nozzle. This means that the gun is used for hammering. And although there is anti-spatter spray for pistols, in the vast majority of gas nozzles are too many splashes, which are well burned. The anti-spatter spray is therefore not used, not well used or not used at all.

There are 4 welders with a NIL level 2 and 12 welders with a level 3 MIG-MAG certificate. Nevertheless, the number of splashes shows that the equipment settings could be much better. What amazed me was that all welders said they had never heard of a transition area at a particular wire-gas combination.

The company has a ring line for mixed gas. Every welder has its own drain point. This tapping point is equipped with a flow meter so that correct adjustment is possible. With the vast majority of welders 20 l/min is set and that is never changed, not even when welding with low currents.

But why use the 1.2 mm contact tip for 1.0 mm wire?

Well…. there is a welder who has been working at the company for a long time. He has no formal welding training and is responsible for all welding work at the company. And as it often happens; if he has a problem, then everyone has that problem and his solution, good or bad, applies to all welders.

So it could happen that when there were wire feeding problems the pressure on the wire was increased for all welders. When that did not help, a 1.2 mm contact tip was mounted and the problem seemed to be solved. Or was it?

When some welders got problems with the gas cover, because the gas nozzle was almost closed with splashes, the gas flow was increased to 20 l/min, for everyone. They took no chances. And even though there were welders who protested, it had to be done in this way. Welders who did want to use the 1.0 mm contact tip could no longer do so because they simply were not ordered anymore.

The lesson of the workplace

At a company, over the course of time, things can happen or arise that are not good for the company, but which continue to exist due to lack of knowledge or motivation. The effects on effectiveness and costs can be considerable. In addition, in this case, there was also a negative effect on the job satisfaction of (a number of) the welders.

Good knowledge of the profession can prevent many of these things. Of course, it is preferable to have the knowledge as much as possible in-house. With targeted and expert experimentation, a good solution will certainly be found. If the knowledge is not (yet) sufficient in-house, it is advisable to hire an external and independent expert. In the above case, the gas supplier was asked for advice, but unfortunately, this has not made a difference. 

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