Duty cycle is essentially the measurement of how much welding can be done in increments of 10 minutes using carbon dioxide gas. One of the aspects that affect the duty cycle is the base gas. And, using an argon base gas affects the duty cycle i.e. a mixture of 75% argon and 25% carbon dioxide, will not cool the welding torch like 100% carbon dioxide. Another factor which lowers the duty cycle is the pulse.
Constant voltage or the current also affects the duty cycle. In the MIG welding process, constant voltage is used with reverse polarity and this causes heat to be produced on the bottom portion of the workpiece and the tip and nozzle are exposed to the heat that is reflected. The carbon dioxide performs like a cooling agent, while the smoke acts like a filtering agent that shields the gun nozzle and tip from the heat that is reflected.
In this process, the pulsing of the weld current many times in a second, causes the arc to seem to be much more hotter and the torch reacts as if the electric current is at the maximum level. This is due to the fact that the arc starts and stops constantly, which consumes more power. Pulse welding also creates much lesser smoke and does not reflect the heat to the contact tip and nozzle of the torch. How does the welding affect the kind of torch you want to make use of? This mainly depends on the heat that is being generated.
Air-Cooled vs Water-Cooled Torches
Air-cooled torches basically rely on thermal transfer and the heat is conducted from the tip to the torch’s handle and then into the cable before it gets radiated into the air. The amount of heat degenerated and the speed at which it is conducted, as well as radiated, depends on the duty cycle.
For instance, power cable guns made of aluminium radiate heat better than copper, however, they are less effective when conducting the current. The torch’s nozzle is insulated both thermally and electrically and the heat radiated by itself.
The water-cooled guns, on the other hand, work differently. Water-cooled or liquid or gas cooled guns essentially rely on water or some other liquid to transfer the heat to the contact tip, nozzle and power cable. This is a much more efficient cooling system, where the heat is transferred from the water to the radiator and then into the holding tank before it is sent back to the torch.
Pros and Cons of Air-Cooled and Water-Cooled Torches
Air-cooled torches are “plug and play” and they have a simple handle, neck and power cable. The chemical, as well as the additional equipment cost to keep the torch functioning optimally is very low.
If you require a hotter or longer weld, then the size of the torch will be heavier and bigger. The tip and the nozzle of the torch are always very hot and the overexposure to heat will cause them to wear out. And, if the duty cycle reaches the maximum level, it gets reduced the next time and this will result in you spending lesser time welding.
Water-cooled torches always remain cool as the water cools down the nozzle and tip after you complete welding, which ensures that the tips and nozzles will last longer. Water-cooled torches are quite lightweight and they are quite buoyant due to the pressure that flows via the cable.
These torches are more expensive and the requirement of the cooling system adds to the expense. The fittings and connections are quite delicate and can break easily. Also, any water leakage in the welding area can cause a lot of mess. The nozzle’s thermal transfer is made of pressed ceramic and it can break very easily, reducing the gun’s efficiency. Also, if the cooling system of the torch is not set up or maintained properly, it can damage the torch. And, while water-cooled torches can reach high amperages, it is quite difficult to achieve the full duty cycle for higher amp guns (500, 600 or 650 amps).
Both air-cooled, as well as water-cooled torches have their pros and cons and you need to evaluate both of them and decide on the one that is best for your welding operations depending on which of them offers better cost-effectiveness and productivity.