We have several large industrial corporations that we supply Plasma Arc Welding (PAW) torches and replacement parts to. One of them came to us for some help resolving inconsistent welds on a Thermal Arc® Ultima 150 Plasma Arc Welding machine with a 4A PAW torch and lead assembly. They were frustrated and had tried many different solutions from a variety of sources. I went through our basic PAW check list (which you can find in the Arc-Zone.com Welding Library– “Optimize Your Plasma Arc Welding Torch”). We did find two areas to improve, but the issue was still there. That’s when I asked “when was the last time you changed your lead set?”
“We just changed torches, we do that pretty often,” he said. “Why would we need to change the leads?”
With Plasma Arc Welding there are two important things to consider:
1. Plasma Arc Welding Torch Lifespan.
PAW torches have a life span of about three months. Now anybody that is familiar with automated TIG applications can’t understand why Plasma Arc Torches fail so often. There is no easy answer, but it is a characteristic of Plasma Physics. There are many more things going on inside that PAW torch than in a TIG torch — two power circuits, two gas distribution and flow paths, two water channels, tungsten electrode insulators etc. Bottom line is you should always have a spare Plasma Arc Welding torch on hand because when they fail they are junk. You’ll have no warning, and you’ll be down until you get it replaced.
2. The Lead Set
I call them leads because they consist of multiple hoses and cables inside a jacketed cover. And they wear out. Operators often don’t think to add the leads to their preventative maintenance schedules but they should.
Over time the power/water leads become filled with debris from the cooling system reservoir. They can also degrade due to the high-frequency current traveling through the cable — the current actually strips the tin plating off of the conductor wires. The tin plating is there to prevent corrosion, and it does, but over time the plating breaks down and becomes a particle in your cooling system which can plug, or restrict water flow and cause overheating.
Cable erosion has another effect — it reduces the current carrying capacity of the power cables. The older the cable, the less current is transferred resulting in resistance which causes inconsistency in your Plasma Arc Welding torch starting, arc transfer and arc control. It can also cause overheating. Any or all of these variables can result in poor weld quality, inconsistent production, and torch failure.
Note: Some people are unsure about using aftermarket PAW torches and parts, and claim it may void their equipment warranty. Many original equipment manufacturers (O.E.M.’s) will suggest that using aftermarket parts will void the warranties on their equipment, however this very seldom actually occurs. The use of high-quality parts in a high-quality system is the best way to avoid equipment problems.
Arc-Zone.com® supplies only the highest-quality products from many of the industry leading manufacturers — including O.E.M.’s and aftermarket suppliers.
You have to remember that Plasma Arc Welding is a global industry serving global markets and there are many high-quality manufacturers in many parts of the world. Your best option is to buy your welding products from a trusted high-quality supplier like Arc-Zone.com® who offers only carefully selected, quality products from known manufacturers.