MIG/MAG WELDING TORCHES: SPECIAL VERSIONS AND WEARING PARTS
In the second part of our series on MIG/MAG welding torches, we take a closer look at special versions. The choice of MIG/MAG welding torches in particular is almost unlimited, with a version for every process variant, welding challenge, and personal welder preference.
High-tech welding torch
The more specialized and complex the application and welding process, the more high-tech the welding torch solution.
The push-pull welding torch: In addition to the wirefeeder in the power source that pushes the wire, on push-pull systems there is a second electric motor in the welding torch that pulls the wire, ensuring the wire feed is very taut. This torch system is highly recommended specifically for aluminum welding where, due to the nature of the material, wires exhibit minimal rigidity, are very fragile, and extremely prone to slippage. Its use is also recommended in conventional steel welding if special extra-long (up to 10 m plus) hosepacks are used. The longer hosepack means that they are extremely prone to slippage, which is why a more rigid wire feed is recommended.
Key to high-quality push-pull systems in general is that the electric motors of the two wirefeeders are perfectly synchronized. The torch motor actual values must be supplied to the power source in real time. This is the only way for the drive to be precisely adjusted so that the wire ultimately stays rigid.
The CMT welding torch: Special high-performance welding torches are required for the absolutely exceptional CMT (Cold Metal Transfer)process. As on the push-pull torches, a wire feed drive unit is also accommodated in the housing of the handle. However, it does not only pull the wire forward, it can also pull it back – up to 140 times a second. Such highly precise wire feeding requires a sophisticated motor control system that communicates perfectly with the power source. The precision of this most specialized of all wire feeding systems allows for colder or lower heat input in the droplet detachment.
Welding torch with pistol grip: The pistol grip is available for conventional push welding torches, as well as push-pull torches. The choice of version depends entirely on the welder’s preference. The pistol grip can aid handling, especially in the case of heavier welding torches, such as CMT torches.
The fume extraction torch: There is a greater awareness these days of health and safety at work, and in welding technology concerns focus primarily around the avoidance of welding fumes. After all, who wants to spend every day working in a fog of foul-smelling fumes? A well-designed fume extraction torch acts like a vacuum cleaner: opening slots immediately behind the gas nozzle extract the air around the weld seam – without affecting the gas shroud around the weld pool. Clean air and a better workplace environment make the job of the welder much more pleasant.
Flexible torch body: Examples of use include where component accessibility is very restricted or the welding position is particularly awkward. It can be connected to the MIG/MAG hosepack using the Mulitlock System. This system utilizes twisted copper pipes in the main that allow the torch body to be bent into more or less any shape within reason, so that the weld seam can be accessed from the best angle. As a result, very special applications can be effected that would be completely impossible for conventional welding torches. However, it is essential to ensure that the torch is bent as few times as possible since the material will be weakened each time the shape is changed. High-quality flex torches can be bent up to 1000 times before they too will need replacing.
Wearing parts on MIG/MAG welding torches
No matter how high the quality to which standard and special welding torches are manufactured – they will all be subject to diverse material wear over time. These individual components need to be cleaned and replaced regularly to ensure the best possible process stability.
Inner liners: The liner is the sheath inside the torch that guides the welding wire. It gives the wire rigidity, from the point where it emerges from the power source to threading into the contact tip. This prevents any slippage and associated process inaccuracies.
The relevant steel inner liners, CrNi liners, or – for aluminum – combination liners are used to suit the different wires. To protect the fragile aluminum wire, combination liners are made predominantly of lead, ensuring minimal friction.
The contact tip sits under the gas nozzle and is responsible for the power transfer to the wire electrode. Since this continually grinds against the copper to make the contact, it will become worn over time. The less effective the contact, the more uneven the arc. For this reason, contact tips should be replaced once they exhibit a certain level of wear. A conventional contact tip can be used for around 120 minutes of on-the-job welding time, which is roughly what a professional welder would aim for in a day.
Contact tips are available in all sizes to suit the specific welding torch, power range, and wire diameter. The greater the power input, the bigger the contact tip since the extra material – mostly copper – helps to absorb heat that is generated.
Gas nozzles are available in different versions – usually as copper gas nozzles since copper does the best job of dissipating heat from the arc and the weld pool. Coated nozzles are also used in aluminum welding, because they reduce the amount of spatter adhesion. It is easy to remove any spatter that is still left on the surface using special cleaning brushes.
High-quality gas nozzles are always designed to be screwed rather than clipped on. This ensures shielding gas cannot escape at the connection point and the gas flow is guided perfectly through the nozzle towards the weld pool. Heat dissipation can also be positively influenced by the thread.
The spatter guard is screwed onto the nozzle fitting, which has holes to allow the shielding gas to flow out. This plastic guard acts in part to insulate the nozzle fitting so preventing any short circuit to the gas nozzle. Its other role is to prevent the gas outlet holes getting choked up with welding spatter. If these holes were to become blocked, the gas flow would be greatly impaired and the gas shroud would be disrupted. This is another reason the spatter guard needs to be cleaned and replaced regularly.
The right MIG/MAG welding torch for every application
As we have seen, many gas shielded arc welding jobs require a universal MIG/MAG welding torch, while some require a more specialist or a highly specific option. At Fronius, we offer a wide range of premium-quality welding torches, so you are sure to find the perfect choice for your power source and process. As you would expect, our service offering includes a comprehensive range of spare and wearing parts.
To find out more about our product portfolio, click here.
If you want to discover more about the fundamentals of MIG/MAG welding, then you can read our blog article here.