In this article, we will explore common weld issues and delve into potential causes and the steps you can take to minimize or eliminate them, ensuring cleaner and more reliable welds.
Issues
Spatter
Spatter refers to those small droplets of molten metal that escape the weld pool and disperse across the welding area. These droplets can cause unintended explosions within the weld puddle, leading to an inferior weld. By recognizing the signs of spatter, you can quickly address the issue and maintain the integrity of your welds.
Causes
Dirty Surface: Before commencing any welding operation, ensure that the surface is thoroughly cleaned. A dirty surface can introduce impurities, contributing to spatter formation. Take the time to remove any rust, oil, grease, or other contaminants that may compromise the weld.
Low CV Voltage: Insufficient voltage can result in spatter. Check your voltage settings and make sure they are appropriately adjusted to provide the necessary heat input for a successful weld. Increasing the voltage within the recommended range can help minimize spatter.
Arc Length: Maintaining the correct arc length is crucial for achieving optimal welds. If the arc length is too short, spatter is more likely to occur. Ensure a proper distance between the electrode and the workpiece, as specified in the welding parameters.
Gas Composition: The gas used in robotic welding plays a significant role in arc stability and weld quality. Certain gas compositions, such as CO2 or argon, can impact spatter formation differently. CO2 tends to provide deeper penetration, while argon promotes arc stability. Make sure you are using the appropriate gas for your specific welding application.
Torch Angle: The angle at which the welding torch is held can affect spatter. If the torch angle is too low, spatter is more likely to be produced. Experiment with slightly increasing the torch angle to achieve a better balance and reduce spatter.
Wire Quality: The quality of the welding wire is crucial for producing clean and precise welds. Using cheap wire can lead to inferior results and increased spattering. Invest in high-quality welding wire that is specifically designed for your welding process and materials.
Moisture and Gas Line Issues: Moisture in the gas lines or leaks can introduce unwanted gases and impurities, leading to spatter and porosity. One way to detect moisture is by observing black soot in the weld. Perform regular checks and ensure that your gas lines are properly maintained and free from leaks. If in doubt, conduct a simple moisture test by placing a paper towel in front of the gas line and monitoring for any moisture accumulation.
Porosity
Porosity manifests as visible holes or cavities on or within the weld, creating a porous and weakened structure.
Causes
Lack of Shielding Gas: Adequate shielding gas is essential for protecting the weld pool from atmospheric contaminants. Insufficient gas coverage can result from a few factors:
Check the Gas Regulator: Verify that the shielding gas supply is not depleted and that the gas flow is appropriately set. Inadequate gas flow can lead to inadequate protection, thereby causing porosity.
Gas Flow Rate: Excessive gas flow into the weld pool can create turbulence and increase the likelihood of porosity formation. Ensure that the gas flow rate is within the recommended range for your specific welding application.
Gas Flow Rate Too Low: Conversely, if the gas flow rate is too low, atmospheric air can infiltrate the weld pool, resulting in porosity. Adjust the flow rate to maintain optimal shielding gas coverage.
Check for Leaks: Inspect the gas lines and connections for any leaks that may compromise the shielding gas supply. Leaks can introduce unwanted gases or allow air to seep in, leading to porosity.
Wind and Fans: When welding outdoors or in areas with strong air currents, such as fans, the shielding gas can be blown away before adequately protecting the weld pool. Ensure that wind conditions are minimized or controlled during the welding process.
Moisture and Gas Line Issues: Moisture or leaks in the gas lines can introduce additional gases and impurities into the weld, resulting in porosity. Signs of moisture, such as black soot in the weld, should be promptly investigated. To test for moisture, place a paper towel in front of the gas line and observe if any moisture is present. Regularly maintain and inspect gas lines to prevent moisture-related porosity.
Gas Composition: Improper gas composition, particularly excessive oxygen levels, can contribute to porosity formation. Ensure that you are using the appropriate gas mixture for your specific welding process and materials.
Travel Speed: Excessively high travel speeds (> 60 inches per minute) can mimic the effects of wind, displacing the shielding gas and leaving the weld pool exposed. Adjust the travel speed to an optimal range to maintain adequate gas coverage.
Dirty Surface: Similar to spatter issues, a dirty surface can introduce contaminants that cause porosity. Thoroughly clean the workpiece before welding to minimize the presence of dirt, oil, rust, or other impurities.
Undercut
Undercut manifests as grooves or cut-out sections in the base material that are not adequately filled with the filler material.
Causes
Voltage or WFS (Wire Feed Speed) Too High: Excessive voltage or wire feed speed can contribute to undercutting. This high energy input causes excessive melting of the base material, resulting in grooves or cut-outs that are not properly filled. Ensure that the voltage and wire feed speed settings are adjusted within the recommended range for your specific welding process and materials.
Incorrect Work Angle: Improper work angle, specifically when the angle is too direct and low, can lead to undercut formation. By adjusting the work angle to a more suitable position, you allow the filler material sufficient time to fill in the grooves and prevent undercutting.
Excessive Travel Speed: Welding at a high travel speed can impede the proper fusion of the filler material with the base material. When the travel speed is too fast, the filler metal does not have enough time to fill in the grooves, resulting in undercut. Adjust the travel speed to a slower rate that allows the filler material to adequately fuse with the base material.