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Air-cooled vs. Water-cooled: Robotics Edition

Posted by Etienne Blouin on Sep 18, 2017 9:30:36 AM
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When it comes to robotic mig welding you often have to ask the question about whether you should go air-cooled or water-cooled. It's always good to have the right tool in the right place for both optimal performance and cost. Basically, looking at water-cooled versus air cooled, there are obvious cases where you would choose one over the other. If, for instance, you were looking at (or are) welding an extreme amperage application with a high duty cycle, you would clearly need a water-cooled torch because and air-cooled would not hold up to such a high level of amperage stress. Conversely, low duty-cycle, low-amperage, and thinner material would be an obvious choice for an air-cooled application. Then, there is everything in between that could be done either way. It is here where you should evaluate air-cooled torches over water-cooled to determine which one is best for your operation, and will get you the most for your investment.

When it comes to the pros and cons for every system, the most common strike against water-cooled is that it is a little more expensive due to the fact that there is more equipment to buy. For instance, you need a water cooler in addition to the water-cooled torch. You also have to ask yourself about the factors that might cause a torch to overheat. Questions and considerations would include items like reflective metal, i.e. aluminum, pre-heated parts that could compromise the natural cooling of the torch, or whether you have tight spaces that you need to weld in. Why would tight spaces matter? Because with a water-cooled torch you can typically use smaller front end consumables for the same capacity.

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Another factor to consider is productivity. Productivity is what welding automation is all about -- getting the most out of your robotic cell for as little investment as possible. Ultimately when looking at productivity it is important to keep in mind some of the advantages water-cooled torches have that lend themselves to greater degrees of productivity. Water-cooled torches are ideally used for those high duty cycle applications much more than air-cooled. Reason being is duty cycle. While both water-cooled and air-cooled robotic MIG guns can run at 100% duty cycle - something an air-cooled manual cannot - that doesn't mean that they can both take as much amperage load or stress.

When you run a water-cooled torch at 100% duty cycle, the internal cooling effect the torch receives from a water cooler will get that torch's heat to dissipate much faster than an air-cooled torch, which must rely on the ambient temperature to get back to an acceptable cooling state. In my experience, water-cooled robotic torches running at 100% can get back to a cooled state in as little as 30 seconds or as long as 2 minutes depending on the amperage load. Water-cooled torch systems can acheive such a quick cooling state because of the external cooling system; there is liquid flowing all the way from the water cooler through the power cable to the front end consumables and all the way back through the system.

With air-cooled, if you were to run a torch at the upper end of it's load limit it would get hotter and hotter through each subsequent welding process. This could affect the quality and consistency of your welds and also would lead to premature wear of consumables - mainly contact tips.

So is the cost between the two systems created equal? One of the factors that is key to decison making is the cost of the initial investment and the cost of using the system over time. The cost differences at the outset are pretty clear. Water-cooled systems will be more expensive up front and there will be the need to invest in a cooler to internally cool the torch system. There's also a little more maintenance involved. You'll have to have coolant and the maintenance schedule is a more intense.

However, running the cell itself will be much cheaper because the consumable life span will last longer from them being cooled internally, not to mention the increase in the duty cycle and overall productivity over the air-cooled.

Air-cooled torches are more simple, rugged, tough, require less maintenance, and are obviously less expensive at the initial investment to get up and running. In the instance of a robot crash, for instance, air-cooled torches typically will hold up better to such a high level of trauma because there's less inside the torch build in terms of tubing, fittings, etc. However, alignment jigs exist for air and water-cooled torches alike, so it's likely any torch that doesn't experience a big crash can be repaired and realianged to a working condition.

So, what are the questions you need to answer for yourself to know if air or water-cooled is right for your robot welding operation? Consider these questions:

  • What is your maximum amperage limit? Air-cooled torches are typically rated at 500 amp on CO2 and water-cooled up to 600 amp. Remember, the closer to the limit you are, the more you will run through consumables and jeopardize weld quality. Anything over 400 amp would lead me to highly recommend a water-cooled solution.
  • What metal and thickness are you welding? More shiny metals like aluminum and thicker material such as 1/4" plate lends itself to a water-cooled welding torch application.
  • What is the duty cycle you're running at? Fifty percent duty cycle or lower would certainly lend itself to an air-cooled torch. Higher than 60% would likely mean water-cooled.
  • What gas mix are you using? This is often a criminally overlooked aspect of robotic welding. A straight CO2 gas will be able to achieve the full amperage load of the torch design, but the more you mix the gas with Argon, Helium, or Oxygen, more amperage capacity you lose. A 75/25 mix of CO2 and Argon, for instance, would likely mean your torch goes from 500 amp to 400 amp in rating, and even more with a higher Argon mix.
  • Are you pulsing? Just like gas mix, pulsing has an adverse effect on welding torch capacity. With pulsed arc welding, the rating of the torch can be reduced by up to 35%. When considering your robot torch package, if you were to have a 90/10 mix with pulsing, but had to maintain a high duty cycle, this would lead to a water-cooled solution.

When deciding between robot torch solution, or if you're evaluating your current welding automation process, having the right tool for the job always will save you time and money. Take a close look at what you're welding and what you're welding with. The right torch solution is out there for your application, that can perfectly match your process.

 

Want to know more about robotic welding torches? We have a guide that explains it all in incredible detail. Download 'The Definitive Guide to Robotic Torches' by clicking the button below!

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Topics: Robotics, Robotic Welding, Arc Welding, Automation, Welding Automation, Water-cooled

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