These are key to preventing undercutting (remember to follow your welding parameters), as is adjusting to the right gun angle. Use the proper welding current and voltage. It causes a weaker area at the toe of the weld and often leads to cracking. Undercutting occurs when a groove melts in the base metal next to the toe of the weld, but is not filled by the weld metal. Preventing them can go far in reducing downtime and costs for rework. Like other weld defects, undercutting and lack of fusion can both affect the quality of your welds. Tip Four: Prevent Undercutting and Lack of Fusion If slag inclusions still occur, increase the voltage until the inclusions cease.įinally, be certain to clean thoroughly between weld passes, removing any slag with a chipping hammer, wire brush or grinding before beginning your next weld pass. Always use the manufacturer’s recommended parameters for a given wire diameter. Next, maintain proper weld heat input, as too low of welding heat input can also cause slag inclusions. Maintain a steady travel speed if you travel too slowly, the weld puddle will get ahead of the arc and create slag inclusions. Also, If you experience slag inclusions at these angles, you should increase your drag angle slightly. In the vertical up position, your drag angle should be between 5 and 15 degrees. In the flat, horizontal, and overhead positions your drag angle should be between 15 and 45 degrees. Secondly, maintain the correct travel angle and travel speed. To prevent worm tracking, use the manufacturer’s recommended parameters for your given wire diameter and lower your voltage setting if necessary. Be certain to provide sufficient space in the weld joint for additional passes, particularly on joints requiring multiple passes. There are four major causes of slag inclusions, all of which can be prevented with proper welding techniques.įirst, avoid incorrect weld bead placement, especially when making multiple passes on thick sections of metal, such as needed for the root passes of welds or wide v-groove openings. Slag inclusions occur when the slag generated by the molten flux in the wire’s core becomes trapped inside of the weld. If worm tracking does occur, reduce your voltage by increments of one half volt until you eliminate the problem. It is best to follow the parameters recommended by the filler metal manufacturer for the specific diameter of welding wire. beyond the contact tip.Īdditionally, to prevent worm tracking-marks on the surface of the weld bead caused by gas that the flux in the core of the wire creates-avoid excessive voltage for your given wire feed setting and amperage. As a general rule, the wire should extend no more than 1 1/4-in. Next, maintain an appropriate electrode extension or stick-out. Using filler metals with added deoxidizers also helps weld through such contaminants, but these products should never replace proper pre-cleaning. To prevent this problem, remove any rust, grease, paint, coatings, oil, moisture and dirt from the base metal prior to welding. It can appear at any specific point on the weld or along its full length. Porosity results when gas becomes trapped in the weld metal. Porosity and wormtracking are both common weld discontinuities that can weaken the integrity of your welds. The two most prevalent type of wire feeding problems-burnback and birdnesting-tend to extinguish the arc prematurely, which in turn can lead to weld defects. They can cause a considerable amount of downtime. Wire feed stoppages and malfunctions are common problems on many job sites. Fortunately, with some know-how and a bit of practice, you can prevent some of the common problems associated with the process and gain the weld quality you need. Still, it doesn’t mean that the process is without its challenges. That’s not surprising, as it offers high deposition rates, excellent chemical and mechanical properties, and the weldability required for these jobs. It has been useful for structural steel erection, heavy equipment repair, bridge construction and other similar applications. Self-shielded flux-cored arc welding (FCAW) has been a viable welding process many years.
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