Welding Inverters

In late 1979, a twenty-four-year-old entrepreneur paid a visit to a research center in Silicon Valley called Xerox Parc. He was the co-founder of a small computer startup down the road, in Cupertino. His name was Steve Jobs. Apple was already one of the hottest tech firms in the country. Everyone in the Valley wanted a piece of it. So Jobs proposed a deal: he would allow Xerox to buy a hundred thousand shares of his company for a million dollars—its highly anticipated I.P.O. was just a year away—if Parc would “open its kimono.”

An engineer named Larry Tesler conducted the demonstration. He moved the cursor across the screen with the aid of a “mouse.” Directing a conventional computer, in those days, meant typing in a command on the keyboard. Tesler just clicked on one of the icons on the screen. He opened and closed “windows,” deftly moving from one task to another. He wrote on an elegant word-processing program, and exchanged e-mails with other people at Parc, on the world’s first Ethernet network. Jobs had come with one of his software engineers, Bill Atkinson, and Atkinson moved in as close as he could, his nose almost touching the screen. “Jobs was pacing around the room, acting up the whole time,” Tesler recalled. “He was very excited. Then, when he began seeing the things I could do onscreen, he watched for about a minute and started jumping around the room, shouting, ‘Why aren’t you doing anything with this? This is the greatest thing. This is revolutionary!’ ”

Are you passing up welding jobs because of your welding machine? It’s too big and awkward to be moving it in and out of your shop. Your welding machine only operates on a certain power (e.g. 220V). Your welding machine is limiting you to one type of welding process (e.g. MIG welding). Do you have to hire inexperienced welders and then worry about the quality of the welding? Maybe you should be looking into inverter welding machines.

Iron Core Transformer & Rectifier

Some people believe the biggest battle in the 19th Century was over which power comes into our buildings. Edison was for DC and Tesla was for AC.
We know AC won but DC is needed for electrical welding. So somehow, welding machines must take in AC and transform it to DC. Therefore all welding machines need a transformer.

The transformer is built on a multiplication formula. The formula has 4 components in calculating the voltage to be transformed: (1) the number of turns of wire on the transformer coil (2) the cross-section area of the transformer core (3) the frequency of the AC voltage to be transformed (4) and various design constraints. Any changes you make to any of the components affect the other numbers: one number gets large; another number(s) must decrease.

The iron core-welding machine is designed on (1) turns and (2) cross- section of the transformer core. Hence some of these welding machines get to be quite big and heavy.

Despite their size and weight, they have become trustworthy and reliable welding machines. If the machine isn’t too old (i.e. you can get parts) they are fairly easy to maintain.

The Inverter

The inverter does its work before it gets to the transformer. The inverter, with the use of sophisticated boards, takes the incoming power and changes the frequency. By necessity (the math formula) the transformer must be reduced in size. In fact, inverters don’t use the laminated steel for transformer. The high operating frequency would create too much heat for laminated steel cores. Nor are the conductors made out of regular magnet wire but copper strip or specially woven wire to deal with the high operating frequency. This leads to one of the advantages of inverter welding machines: lighter and smaller.

The inverter has the ability to be like an experienced welder. An experienced welder becomes very good at adjusting to his welding machine. He determines what the machine and wire are doing than makes adjustments to his welding technique to produce good welds. The inverter adds in sophisticated control boards that are monitoring the input and output power, now the control board makes the adjustments. So, the inexperienced welder now has “experienced welder” making the adjustments to the welding dial according to how he welds: too far away? Too close? The control board makes the adjustment.

Inverters aren’t fussy about the incoming power. The control board notes the input and makes the changes. The input power isn’t consistent, no problem: the adjustment is made automatically. On some inverters, the machine can automatically adjust to the incoming power (230V to 115V) and you just change the plug.

Inverters and Aluminum Welding

In TIG welding aluminum the penetration of the weld comes from the negative side of AC power. And the positive side of AC, penetration s reduced and more heat goes into the electrode tungsten. But during the positive side of the cycle, the arc removes oxides from the surface of the aluminum, making it easier to weld. AC gives out equal portions of positive and negative but this is inefficient, you don’t need that much positive. So they designed power supplies to vary the proportion of positive and negative (65,35%) to give good penetration and cleaning action. However a lot of heat was going to the tungsten requiring large diameter tungsten.

Inverters are able to make more of adjustment to the positive/negative ratio. It has been found that 15% positive is going to make the process more efficient, more penetration, and reduce heat going to the tungsten = so a smaller diameter and pointed electrode can be used.

The ability to manipulate the incoming power, the use of control boards, and the use of software makes us believe that better welding power sources are yet to come.

If you think this could be a big help, give us a call; we’d be glad to help you reach a solution that works for you.


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