MIG Gun Consumables: Tips to Extend Life
Consumables for the welding gun can significantly impact the productivity and welding quality in an operation. This makes it important to keep consumables properly cleaned and maintained, to help minimize unplanned downtime, extend consumable life and optimize performance.
The Heat Factor
The heat produced in the welding process can have a significant impact on the cleanliness and longevity of MIG consumables. Processes like pulsed MIG and/or higher amperage applications tend to subject consumables to higher levels of heat, as do applications in which there is a large amount of reflective heat. Those include applications with tight tooling or those that require welding in restricted areas.
The hotter the consumables become during the welding process, the softer the material (usually copper or brass) becomes, resulting in a surface area that is much more prone to accumulating spatter and failing prematurely.
To avoid such problems, it is important to determine the best consumables for each application and consider how they will be managed throughout the course of a welding shift. For example, high-amperage applications (those above 300 amps) most often benefit from using heavy-duty consumables because they have greater mass and are capable of dissipating the heat more readily. However, if the welding procedure dictates that the contact tip must be changed frequently, a standard-duty contact tip may suffice. The goal is for companies to determine which consumables — heavy- or standard-duty — are most capable of withstanding the duty cycle and heat of the application. A reliable welding integrator can often help with the selection.
The Anti-Spatter Solution
Using an anti-spatter compound can help keep MIG consumables clean on both semi-automatic and robotic welding applications; however, it must be used sparingly. On a semi-automatic application, welding operators should dip only the front inch and a half of the nozzle into the anti-spatter compound. Submerging the nozzle in the anti-spatter compound can saturate the nozzle’s fiberglass insulator and also potentially plug up the gas holes on the diffuser. This build-up may cause the nozzle to fail prematurely or result in porosity in the welds due to the unbalanced gas coverage. In robotic applications, only the minimum amount of anti-spatter compound required for the application should be used. Using too much can cause build-up on the consumables and/or cause debris to accumulate and clog the nozzle, leading to poor gas coverage, inconsistent electrical conductivity or shortened consumable life.
Another important way to combat spatter is to inspect the nozzle for build-up on a regular basis and clean it with a soft wire brush or spatter-cleaning tool as needed. Welding operators should never hit the nozzle against the tooling or work piece to loosen spatter. Doing so can dent, misshape or compromise the smooth surface finish of the nozzle, which creates greater areas for spatter to adhere to and reduces the life of the consumable.
Proper Storage and Handling
Always keep MIG consumables in their original packaging until they are ready for use. Opening them and placing them in a bin can lead to scratches or dents that allow spatter to adhere and will ultimately shorten the products’ life. Similarly, removing contact tips or diffusers from their packaging and storing them in open or dirty containers can cause dirt and oil to accumulate in the threads, which can impede them from properly seating together. Also, companies should always keep storage containers for new consumables separate from those for discarded ones to avoid selecting an old contact tip or nozzle that may have dents or scratches and be prone to spatter accumulation. Finally, welding operators should always use clean gloves when handling or replacing contact tips, nozzles and diffusers to prevent dirt, oil or other contaminants from adhering to them.
Establish and Maintain Good Connections
Installing MIG consumables correctly and inspecting them periodically for good connections minimizes the chance of poor conductivity and with it, spatter accumulation or premature failure. Welding operators should always follow the GMAW consumable manufacturer’s suggestions for contact tip and gas diffuser installation, using a pair of channel lock pliers, welpers or other such recommended installation tool. Never use wire cutters or side cutters — too much pressure from these tools can damage the inside diameter of the contact tip, which leads to poor welding performance and a shortened lifespan. Also these tools tend to scratch the surface of the consumables leaving marks that attract spatter.
A good rule of thumb is to hand tighten the contact tip until it is fully seated into the diffuser, then grip the contact tip with an appropriate tool as close to the base as possible, tightening it 1/4 to 1/2 turn past finger tight. This procedure helps ensure a good connection that minimizes electrical resistance, overheating and damage to the consumables, as well as excessive spatter accumulation. Follow the same procedure for installing and tightening the diffuser so that it fully connects with the neck. Also note, some contact tips available in the marketplace can be installed and held in place by hand tightening the nozzle. Check the manufacturer’s recommendation for proper installation instructions.
Inspect consumable connections regularly to ensure that they are secure.
Trim Liners Correctly
An improperly trimmed and installed liner can cause a host of wire-feeding problems that lead to downtime to rectify. It can also affect the performance of MIG consumables, how clean they stay and their longevity. Cutting a liner too short can cause the liner to be misaligned with or in the gas diffuser. The result is a welding wire that feeds off-center, leading to premature contact tip failure. Liners that are too short can also lead to the build-up of debris between the liner and retaining head, which causes wire feeding issues and poor weld quality. In some cases, the gap that is present between the gas diffuser and liner when a liner has been cut too short may cause the welding wire to catch, resulting in small shavings that can plug up the contact tip and cause it to fail quickly. A liner that’s too long can cause kinking that again leads to wire-feeding issues that shorten the life of the contact tip. Always make sure that to remove any burrs or sharp edges after cutting a liner to ensure smooth and consistent feeding of the welding wire.
|1/4-in. Recess||> 200||1/2 – 3/4in.||Spray, high-current pulse||Metal-cored wired, spray transfer, argon-rich mixed gas|
|1/8-in. Recess||> 200||1/2 – 3/4in.||Spray, high-current pulse||Metal-cored wired, spray transfer, argon-rich mixed gas|
|Flush||< 200||1/4 – 1/2in.||Short-current, low-current pulse||Low argon concentrations or 100 percent CO2|
|1/8-in. Extension||< 200||1/4 in.||Short-current, low-current pulse||Difficult-to-access joints|
Welding operators should always consult with the liner manufacturer’s recommendation for proper trimming and installation instructions. It is also important that they wear gloves when handling the liner and avoid dragging it on the ground to prevent debris from being introduced into the MIG gun. Such debris can lead to weld contamination and/or poor consumable performance.
Mind the Contact Tip Position and Nozzle Size
The position of the contact tip (extended or recessed) affects how well consumables last, along with how clean they stay. So too does the nozzle used in conjunction with a specific contact tip and the wire size. The farther the contact tip extends from the nozzle, the closer it is to the arc and the more prone it is to reflective heat. The result is a greater tendency toward spatter accumulation and a greater opportunity for burnbacks. Using a recessed contact-tip-to-nozzle relationship when possible can minimize this problem and provide better shielding gas coverage at the same time.
For companies with applications that require access into restricted areas, it is important to select a nozzle that provides that access, but isn’t tapered so much that it minimizes the space around the contact tip. If there isn’t enough space for shielding gas to flow out of the nozzle, it can cause the shielding gas to hit the work piece and begin jetting back and/or swirling. The result is the pulling of oxygen into the weld pool and an increase in spatter. Too, the smaller the bore size on the nozzle, the more prone it is to absorbing heat (because there is less mass to that portion of the consumable) and having spatter adhere to it.
As a general rule, companies should select the largest consumable that will work for the application and provide the necessary joint access. Larger consumables are more able to resist heat and spatter build-up, and they often last longer as a result.
Selecting consumables with the right material for the application is important, too. For example, brass nozzles tend to resist spatter well and are good for lower-amperage applications (100 to 300 amps), whereas copper nozzles are better for high-amperage applications (above 300 amps) or for those with longer arc-on time.
Lastly, companies should always pay attention to the manner in which they manage consumables. When possible, having the same consumables throughout the welding operation can help welding operators better maintain the consistency of the consumable performance and troubleshoot problems more quickly when they occur. The result can be longer-lasting, cleaner consumables that provide more reliable performance and quality.