Helpful Tips To Troubleshoot Common Defects That May Occur During Mig Welding
Improper technique or parameters, such as inadequate shielding gas coverage or incorrect travel speeds, are common causes of weld defects.
Save both time and money by avoiding common welding errors. Improper technique, parameters, or equipment settings can lead to weld defects. When defects occur, it’s crucial for welders to have the knowledge to fix them quickly.
Porosity is a common MIG welding defect caused by gas becoming trapped in the weld metal. Inadequate shielding gas coverage is a major culprit, but there are several ways to address this issue. Check the regulator or flow meter for adequate gas flow, inspect the gas hoses and welding gun for leaks, and block off the welding area if drafts are present.
To ensure proper shielding gas coverage, use a large enough nozzle to fully shield the weld pool with gas, keep the nozzle clean and free of spatter, and follow the manufacturer’s recommendation for proper contact tip recess. Other causes of porosity include dirty base material, excessive gun angle, and extending the wire too far from the nozzle. Remember to extend the wire no more than 1/2 inch past the nozzle.
Wet or contaminated shielding gas cylinders can also cause porosity. Replace damaged cylinders immediately to prevent further defects.
In MIG welding, cold lap and lack of fusion are two distinct but related issues. While the terms are often used interchangeably, they can occur independently or together.
Lack of fusion happens when the weld metal fails to fuse completely to the base metal or preceding weld bead. This is often due to improper welding gun angle or incorrect travel speed. To avoid this issue, maintain a 0-15 degree gun angle during welding and keep the arc on the leading edge of the weld pool. Increasing travel speed may also be necessary to maintain the correct arc position. Insufficient heat in the weld can also cause lack of fusion, which can be remedied by increasing voltage settings or wire feed speeds.
Cold lap, on the other hand, occurs when the weld overfills and overlaps on the toes of the weld due to incorrect travel speeds. To prevent this issue, increase travel speed as needed. By understanding the differences between cold lap and lack of fusion, welders can troubleshoot and correct these issues more effectively.
When welding thin materials less than 1/8 inch or about 12 gauge, burn-through is a common issue that occurs when the weld metal penetrates completely through the base material. Excessive heat is the primary cause of burn-through, which can be remedied by reducing voltage or wire feed speed. Increasing travel speed may also help, especially when MIG welding on materials that are particularly prone to heat buildup, such as thin aluminum.
There are various factors that can lead to an excessive amount of spatter during the MIG welding process. These include insufficient shielding gas, dirty or contaminated base materials, high voltage or travel speeds, and excessive wire stickout. To prevent spatter buildup, it is important to ensure proper shielding gas flow, thoroughly clean base materials, lower weld parameter settings, and use a shorter stickout. When using self-shielded flux-cored wires, welding with straight polarity and using a drag technique can help minimize spatter. Additionally, using the correct contact tip size and ensuring that the contact tip is not worn or improperly recessed can also prevent excessive spatter. If spatter accumulation is observed when using flux-cored or metal-cored wires, increasing voltage may be necessary.
The objective of welding is to produce a smooth and flat weld bead. Welds that are either too concave or convex can compromise the quality of the final product.
Concave weld beads are commonly observed when welding in vertical-down applications, as gravity works against the welder. To avoid concave weld beads, adjust the parameters to a lower setting, which will make the weld pool less fluid and more capable of filling in the joint. In the flat or horizontal position, concave weld beads are often caused by high voltage, slow wire feed speed, or fast travel speed.
Convex weld beads are high and rope-like welds that typically occur in flat and horizontal welding, as well as in fillet welds when the parameters are too cold for the material. Convex weld beads usually have poor fusion of the toes. To prevent convex beads, increase the voltage. Always adhere to recommended welding procedures, use the appropriate shielding gas for the material, and ensure that the wire polarity is correct.
To reduce the amount of time and money spent on fixing MIG weld defects, it is important to adopt a systematic approach to troubleshooting each issue as it arises. Start by identifying any variables that may have changed during the welding process, such as parameters or welding technique. Then, consider the following tips as potential solutions to the problem.