For structural applications, some contractors have made the switch from stick welding to self-shielded flux-cored welding to increase productivity and give themselves a competitive edge.
Self-shielded flux-cored welding offers much greater travel speeds and deposition rates compared to stick welding, while also eliminating the frequent stopping and starting required to change out stick electrodes.
For contractors considering this conversion, there are some key factors to keep in mind to help choose the right self-shielded flux-cored welding gun for the job—and to use and maintain it properly. Gun options such as heat shields, configurable necks, and adjustable cable lengths can help improve weld quality, efficiency, and operator comfort in self-shielded flux-cored applications.
SELF-SHIELDED FLUX-CORED WELDING
Self-shielded flux-cored welding is becoming more common on jobsites for several reasons. In addition to the greater productivity and deposition rates of the process, it also doesn’t require a shielding gas to protect the weld pool, eliminating the hassle and cost of buying and storing gas cylinders on the jobsite.
Not using shielding gas also eliminates the need to set up tents or wind shields to protect the weld from the elements and the need to use specialty nozzles to control gas flow as is common with a gas-shielded flux-cored process.
Some training may be required for welders who are used to the stick welding process. The different ergonomics of the self-shielded flux-cored gun compared to the stick electrode holder require approaching the weld from different angles and using different travel angles and pressure.
When stick welding, the operator typically begins with the electrode (and therefore his or her body) farther from the weld. As the rod shortens during welding, the welder gets physically closer to the weld, applying pressure to the stick electrode as it melts into the weld pool. In self-shielded flux-cored welding, the welder stays in the same spot, maintaining a consistent distance between the contact tip and the weld pool. The proper contact-tip-to-work distance depends on the application, but at least ½ inch is a good rule of thumb.
Self-shielded flux-cored welding can be prone to slag inclusions if proper technique isn’t followed. Regularly inspect the contact tip to ensure it’s free from spatter and debris buildup, which helps ensure smooth wire feeding. Properly clean the weld between passes.
WELDING GUN OPTIONS
Welding guns for self-shielded flux-cored applications are available in various configurations. Choosing the right gun can help contractors tailor it to their specific needs and applications. Consider these features:
- Heat shield: One of the most common features on self-shielded flux-cored welding guns is a hand guard or heat shield, which is available in different sizes. In applications that require access to a corner joint, choosing a smaller guard increases maneuverability and provides more access. When welders need to run at a higher voltage and deposit more filler metal into the weld, using a larger guard helps deflect the higher heat.
- Neck lengths and bends: Gun necks are available in varying lengths and bend angles. A slimmer neck provides a better view of the weld pool and improves access to tight areas, for example. A shorter neck typically provides more control compared to a longer neck. Lightweight, rotatable necks can also reduce operator fatigue and improve weld visibility.
- Replaceable or fixed cable liner: Some self-shielded flux-cored gun models are available with either a replaceable cable liner or a fixed cable liner. A replaceable cable liner provides benefits in harsh and demanding environments, since self-shielded flux-cored welding can be hard on equipment and consumables. Replaceable power cable liners provide quick and easy cable maintenance and can extend product life since welders can change out components that experience high levels of wear. In addition, choosing a replaceable cable liner with internal trigger leads means there is no external trigger cord that can catch on surrounding objects. Conversely, fixed cable liners tend to be larger, which can be an issue when welding in corners or tight spaces.
- Dual schedule switch: A self-shielded flux-cored gun with an optional dual schedule switch allows for wire speed adjustment while welding. In some guns, this switch is integrated into the handle to keep it protected from spatter. The ability to toggle between weld parameters easily—without having to stop welding and change settings—saves time and improves productivity.
KNOW THE BASICS
There are ways to extend the life of the gun and consumables. The necessary frequency of gun and consumable maintenance depends on the application and the welding environment.
Conduct routine checks to ensure front-end consumables are in good shape and all connections are tight. This helps keep heat resistance low and ensures proper electrical conductivity so the gun and consumables last longer. Consider using a rotatable gun neck with a collet-style connection, which makes it easier to drop the neck in and tighten it. Consumables that use compression fittings also provide more efficient energy transfer and less overheating to help extend product life.
Be sure to keep the contact tip clear of spatter buildup and inspect the tip for signs of wear or keyholing, and also inspect the cable for any damage or nicks.
While the self-shielded flux-cored process is capable of welding material with dirt, oil, or mill scale, remember that better surface preparation delivers better results in any welding application. Properly cleaning the base material will help produce better welds.
Because flux-cored welding produces a slag and spatter, there is also a need to remove the slag between passes and for post-weld cleaning. Be aware that travel angles beyond 20 or 25 degrees can increase spatter and arc instability. With self-shielded flux-cored welding, it’s recommended to use a drag technique with a travel angle of 5 to 15 degrees.
As more contractors look for ways to increase productivity and efficiency on the jobsite, the use of self-shielded flux-cored welding grows. Choosing a welding wire designed to improve a weld’s chemical composition or deposition rates can provide even more benefits.
The self-shielded flux-cored process can be a good alternative to stick welding in many outdoor applications that boosts productivity and reduces costs.
ABOUT THE AUTHOR
Roger Robey is a product support specialist with Bernard. For more information about Bernard and its products, visit www.bernardwelds.com.
Modern Contractor Solutions, October 2018
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