Adjust wire feed speed (250-400 IPM) and voltage (18-24 Volts), ensure low humidity (<60%), and use clean materials.
Causes of Worm Tracks in Flux Core Welding
Influence of Welding Parameters
Wire Feed Speed
Optimal wire feed speed is crucial for achieving a stable arc and preventing worm tracks. Too fast or too slow speeds can lead to imperfections.
- Too Fast: Causes excessive spatter, leading to worm tracks as the molten metal does not have enough time to flow into the weld pool properly.
- Too Slow: Results in a lack of penetration because the arc isn’t hot enough, making it difficult for the metal to fuse properly.
| Setting | Effect on Weld | Optimal Speed Range |
|---|---|---|
| Too Fast | Excessive spatter, worm tracks | 250-400 inches per minute |
| Too Slow | Lack of penetration, poor fusion | 150-250 inches per minute |
Voltage Settings
Proper voltage setting is essential for controlling the arc length and heat input, affecting the weld’s appearance and integrity.
- High Voltage: Leads to a wider, flatter weld bead, increasing the likelihood of worm tracks if not controlled.
- Low Voltage: Produces a narrow, peaked bead that may lack sufficient coverage and fusion.
| Voltage Level | Impact on Weld | Optimal Range |
|---|---|---|
| High | Wider, flatter bead, potential worm tracks | 18-24 Volts |
| Low | Narrow, peaked bead, poor fusion | 16-20 Volts |
Environmental Factors
Humidity and Temperature significantly impact the welding process, influencing the flux’s performance and the overall weld quality.
- High Humidity: Moisture can get absorbed by the flux, leading to porosity and worm tracks as the moisture vaporizes during welding.
- Extreme Temperatures: Very cold or hot conditions affect the welder’s performance and metal’s properties, potentially leading to worm tracks.
| Condition | Effect on Weld | Optimal Conditions |
|---|---|---|
| High Humidity | Increased porosity, worm tracks due to moisture | Relative Humidity < 60% |
| Extreme Temperature | Altered weld properties, potential for worm tracks | 50°F – 80°F (10°C – 27°C) |
Material and Equipment Considerations
Base Material Quality and Condition of Welding Equipment are pivotal in preventing defects such as worm tracks.
- Base Material Quality: Impurities or coatings on the base material can lead to inadequate fusion and the formation of worm tracks.
- Condition of Welding Equipment: Poorly maintained equipment can cause irregular wire feed speed and fluctuating voltage, leading to worm tracks.
| Factor | Impact on Weld | Preventive Measure |
|---|---|---|
| Base Material Quality | Impurities lead to poor fusion, worm tracks | Use clean, high-quality material |
| Condition of Welding Equipment | Irregular feed speed/voltage, worm tracks | Regular maintenance and calibration |
Conclusion
Understanding the causes of worm tracks in flux core welding and adjusting the welding parameters, environmental conditions, and equipment maintenance can significantly improve weld quality. Careful attention to wire feed speed, voltage settings, humidity, temperature, and material quality is essential for achieving defect-free welds.
Preventing Worm Tracks in Flux Core Welding
Optimal Welding Techniques
Proper welding techniques are paramount to ensuring minimal occurrence of worm tracks. Consistent travel speed and angle provide even heat distribution and proper metal transfer. Travel speed should be set in a way that the weld pool cools down enough but not too cold, so it may vary from 5 inches per minute for the thin material to 12 inches per minute for the thicker material. The angle of welding gun should be set between 15 and 45 degrees, based on the position of welding and direction.
Technique Adjustments Based on Material Thickness
Change of the welding technique according to the thickness of material is crucial to reduce the likelihood of defects. While for the thin material the speed should be increased, allowing to prevent excess heat and, in turn, burn-through and worm tracks, the slower travel speed is required for thick materials to ensure adequate penetration and bonding. Thicker materials may require changes in voltage from 22 to 29 and wire feed speed of about 300 to 400 inches per minute whereas thinner materials are acceptable to use with lower settings.
Selection of Flux Core Wire
Selection of flux core wire is crucial to the quality of welding and chances of worm tracks. E71T-1 wire is the most common due to its versatility and good mechanical properties, allowing for both single and multi-pass welding with minimal chances of worm tracks. Self-shielding E71T-11 wire is also popular for field purposes but is more likely to cause worm tracks in suboptimal conditions. Selecting the right wire diameter is important, as 0.035 inches works well for large array of general fabrication needs, having a proper balance between productivity and weld quality.
Wire Types and Their Impact on Quality of Weld
The influence of wire type on the welding process and quality includes the likely occurrence of worm tracks. Rutile-based flux wires provide for better slag detachability and capable of ensuring the formation of smooth welding beads. Basic flux wires are suitable when welding of thick material or greater mechanical properties are required but it may take skilled welder to prevent excessive worm tracks.
Selection of Shielding Gas and How It Works
While in some cases flux core wires work without any additional shielding gas, it is likely to provide for improved quality of the welding and reduced chances of worm tracks. For example, CO2 or a mixture of argon and CO2 provides for more stable arc, better penetration, and smoother beads. Pure CO2 penetrates deep, which is best for the thick material but may cause greater spatter. An argon-CO2 mix is often used in a volume of about 75% of argon and 25% CO2, providing for stable arc and less spatter formation, which provides for a clean weld without many defects.
Troubleshooting and Correcting Worm Tracks
Query
Provide a guide on troubleshooting and correcting worm tracks in flux core welding.
Procedure
Steps to problem-solving worn tracks in flux core welding include: inspection of welding, identification of root causes, and implementation of corrective action.
Step 1: Inspection and Diagnosis
Inspection and Diagnosis Techniques
Visual Inspection and Testing Methods
Visual inspection is the simplest and most common inspection used to identify worm tracks. This involves observation of the weld bead’s surface for the surface defect. The welder will be able to know that their flaw is caused by a worm when the appearance of the weld contains patterns or plows that resemble those of a worm . Visual inspection can be enhanced by carrying out non-destructive testing (NDT) tests. The common type of NDTs that can be used to detect the worm tracks in welding are ultrasonic testing (UT) and radiographic testing (RT) . UT will offer details on a weld’s internal materials revealing defects and irregularities that could lead to the development of worms. Radiographic testing will also reveal hidden defects within the metal.
Step 2: Corrective Actions for Existing Worm Tracks
Grinding and Rewelding Procedure
After the worm tracks have been identified, the easiest way to perform corrective action is to mark the section and then cut it off using a grinder. The metal should be removed from the welds beyond the tracks to achieve smooth surfaces . After the grinding is done, the welder should now check the work and then proceed with the rewelding process. During this process, the welding parameters during the welding process can be adjusted. For instance, a welding machine should be set to a reduced feed speed or increased voltage settings for the desired wire . The welder should choose a welding technique that promotes the stability of the arc and penetration during the welding for rewelding application. Additionally, an appropriate type of FCAW and sometimes a shielding gas for the reapplication should be selected.