Wednesday, March 29, 2017 / Perth Australia / By Niekie Jooste

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The Special Process - Issue #013

• Just Do It
• Future Vision, Current Action
• Welding Power Source
• Welding Power Sources of Tomorrow

Just Do It

What does it help you to predict that the bus is on its way, but still get run over by it? How are you different to the guy that was run over by the bus, oblivious to the fact that he was walking in a bus lane?

Today we acknowledge that tomorrow is for planning, but that today is for action!

With that mindset, in this edition of The WelderDestiny Compass, we look at the present state of welding power sources, and consider what could happen with the technology in the future.

In this way, we are actually busy hailing the bus right now, so that we can jump on when it does arrive.

In response to the last edition of The Welder Destiny Compass, regarding welding as a special process, a good point was raised by Kevin Bohne regarding the frequent lack of verification of production welding. Click here to take a read and get involved in the conversation...

If you would like to add your ideas to this week’s discussion, then please send me an e-mail with your ideas, (Send your e-mails to: compass@welderdestiny.com) or add a contribution directly into the comments form on the bottom of the e-zine page on the WelderDestiny website.

Click here to add your contribution directly to the WelderDestiny website...

Now let's get stuck into this week’s topics...

Future Vision, Current Action

Our very existence here at The WelderDestiny Compass is justified by looking into the future and getting ourselves ready for the changes that are coming in the age of automation. I believe this is a noble endeavour, but it does mean that we run the risk of loosing sight of the present.

Anticipating and planning for the future only has meaning if we act in the present. If our actions are only ever future dreams in our minds, then we will dream our lives away, instead of living our lives. Anticipating the future only has any meaning if it spurs us to action in the here and now.

We always need to look for the current opportunities around us, rather than worrying about the future or regretting the past. These opportunities may be in our relationships, or in our professional lives. Seeing as our beat is not advice on personal relationships, (thank heavens for that) we will keep our focus on opportunities within the welding industry.

An area where there has been quite a lot of advances in the last decade or so, has been in welding power sources, so we will look at the opportunities for immediate action that this presents to us.

Welding Power Sources

In welding we need relatively high amperages with relatively low voltages. The traditional way to achieve this from the normal electricity that we have available in homes and factories is through the following process:

• Take the alternating current (generally alternating at 50 – 60 cycles per second) as supplied through the traditional power system. Either single phase or 3 phase.
• Use a transformer to change this to an alternating current (AC) output of higher amps and lower volts than that supplied by the power company.
• Some cheaper power sources will just use this AC output to weld with.
• The more upmarket power sources will then use some rectifiers to change the AC current to direct current. (DC) The DC output is then used to weld with.

Obviously there are other kinds of power source components to make all this work smoothly, and provide us with controls to be able to control the output in terms of current or voltage.

In traditional power sources, the ability to control the output current by changing either the amps, or the volts, is a function of the way that the transformer was wired. Wire the transformer differently and you get either a constant current (CC) power source, or a constant voltage (CV) power source. Constant current power sources are good for manual processes like SMAW (stick welding) or GTAW, (Tig welding) while constant voltage power sources are good for wire feeding welding processes like GMAW or FCAW.

The main restriction in this system is that the transformer only operates at the mains power frequency of 50 to 60 cycles per second. (50 – 60 Hertz)

In inverter power sources, the process has been modified as follows:

• Take the alternating mains current (generally alternating at 50 – 60 cycles per second) as supplied through the traditional power system. Either single phase or 3 phase.
• Use rectifiers to change this AC to DC power.
• Use an electronic "chopper" circuit to change the DC to a very high frequency AC current. The frequencies are typically greater than 10 000 cycles per second. (10 kHz)
• This high frequency AC current is then used in a transformer to change the supplied amps and voltages to those required for welding. The high frequency makes the transformer much more efficient than it would be when operating at 50 – 60 cycles per second.
• The high frequency AC output from the transformer is again changed to DC current by way of rectifiers.
• Additional electronics tailor the output signal to provide control.
• The output is then used to weld with.

The immediate advantage of using the inverter technology is therefore to significantly reduce the amount of copper needed in the transformer, due to the increased efficiency of the transformer. This means that a much smaller and lighter power source can do the same job as a bigger and heavier power source. This is however at the expense of having to add much more electronics.

There are however secondary advantages of this inverter technology. These advantages flow from the fact that we are in any case using electronics to tailor the power output current to provide control of the welding current.

With only small additional effort and expense, the inverter power source can be made to have either a CC or a CV power source characteristic. This can mostly be done by merely flicking a switch on the power source.

With some more relatively minor additions of effort and expense, electronics can be added to pulse the power output, rather than just supplying a constant output.

A bit more cost and effort, and you can tailor the shape of the output current when using a process like dip transfer in GMAW.

In short, once you have the electronics to manipulate the welding current output, the sky is the limit. Not only can you manipulate the current in terms of volts and amps, but you can actually start manipulating the electromagnetic fields associated with the arc.

Welding Power Sources of Tomorrow

Once the "base" parameters have been set by the welder, any additional dynamic changes that the power source makes is only based on measurable changes happening in the arc. Many undesirable changes or effects, are not perceived by the power source, so it is not able to respond to these dynamically.

As an example, arc blow is a common problem for welders. The magnetic fields around the arc conspire to push the arc in unfortunate directions, resulting in welding defects.

Now, if magnetic fields can move the welding arc in the wrong direction, then surely magnetic fields can also be used to dynamically move the arc in favourable directions. Much research has been done to develop systems that use this principle, but I am not aware of any significant commercial applications at this time. But, surely it is only a matter of time before this arrives.

Another effect associated with this manipulation of the magnetic fields around the arc, is the use of "electro-magnetic stirring" of the weld puddle. This changes the way in which thermal currents move in the weld puddle, allowing greater or lesser weld penetration, or a narrower or wider arc etc.

While such advances promise much, they will only really make a big impact once there is a visual feedback mechanism for the power source to help it to dynamically change the magnetic fields as required, to achieve the desired welding outcome.

These kinds of changes need to happen so rapidly, that it would not be practical for a welder to provide the feedback manually.

But what would happen if the artificial intelligence and virtual reality vision system that we previously discussed, were able to interface with the welding power source?

Suddenly all the promise of these power source advances will be unleashed!

So, what are the opportunities right now? Get to know the latest power sources, and what controls they provide. Some features will come across as "gimmicky", but ask yourself what additional technology will make that feature really useful?

While evaluating the latest generation power sources, also look for which of those power sources have the most predictable arc characteristics. Unfortunately some of the power sources claim much, but they have major shortcomings in their control circuits, so their features are sometimes more of a curse than a blessing. Try to identify the power source manufacturers that are delivering on their promises.

The real advantage in future power sources will be in the electronics. Get to know which manufacturers know how to use their electronics, and which are groping in the dark. Once the supporting technology arrives, you will not have to guess which brand of power source to invest in.

Yours in welding

Niekie Jooste

P.S. What are your thoughts on preparing for the future by taking action today? Which aspects of welding power sources show the most promise for the future? Please share your stories, insights and even fears or wishes regarding today's topics directly on the e-zine page on the WelderDestiny website.

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