Gas metal arc welding (GMAW) is believed to be one of the easiest welding processes to learn and perform. The primary reason to its ease of use is due to the fact that the power source does most of the work as it adjusts the welding parameters to fit the different welding conditions the welder may be faced with. The ease of learning the process of gas metal arc welding allows welders to become proficient in the technique with limited time spent training and learning the process. This can be beneficial and yet can cause problems down the line. Welders who are just starting to use the process often find themselves creating welds that are inferior and many welders are unsure of how to correct these problems. The tips listed below were designed to help gas metal arc welders recognize their errors and take the appropriate steps to reduce them from repeatedly occurring.
- Porosity – The most common reason behind porosity occurring in welds is that the surface of the metal being welded hasn’t been properly cleaned prior to welding. In order to reduce porosity welders should use a deoxidizer within the wire. These deoxidizers can be silicon, manganese or trace amounts of aluminum, zirconium or titanium. Before welding you should test the different types of wire to see which type will work best with the base metals you will be working with. Along with choosing the correct type of wire, you will also want to thoroughly clean the surface of the metal either with a grinder or chemicals. It is important that when using chemicals that you not use a chlorinated degreaser anywhere near the welding arc. The fumes created by this type of cleanser often react with the arc and can produce toxic fumes.
- Shielding Gas – Problems with the shielding gas have also been known to create porosity in welds. In gas metal arc welding the use of a shielding gas is required to protect the weld puddle from contaminants in the air and to act as an arc stabilizer. If there is any disruption to the shielding while the weld is being performed porosity can occur. To keep porosity to a minimum it is recommended that the shielding gas be produced at the appropriate flow rate. This can be measured by using a flow meter. If you are using a pure carbon dioxide shielding gas, you should use a meter that has been specifically designed for that type of gas. Other reasons that your shielding gas may become disturbed are if you are performing the weld outdoors. Wind will disrupt the flow of the shielding gas and allow for contaminants to land in the weld puddle. If you are welding in a windy area, you may want to use wind screens to help reduce the amount of wind hitting the area where you are working.
- Base Metal – Another common cause of welding problems occurs if the base metal does not correctly bond with the material being used to join it. To prevent this problem you should use a different grade of steel or change to a slag-generating welding process.
- Improper Bead – The appearance of an improper bead indicates that the welder was using the wrong settings and that the heat was set too low for the type of metal they were working with. To remedy this problem the welder must determine the proper amperage for the type and thickness of the metal being used. Another problem that can cause an improper bead to form is the welder’s technique. To avoid this the welder should use a push technique at an angle of five to ten degrees. Problems with the work cables can also cause the occurrence of improper beads. If your cables become overheated your weld can show signs of an improper bead. If your cables are showing symptoms of becoming overheated, you should replace the cable and make sure that you are using the right size for the type of current you are using.
These are some of the most common types of problems experienced by welders using the gas metal arc process of welding. We hope that some of the tips we have listed will help you produce welds of a higher quality.
Picture Source: www.bernardwelds.com
Reference: http://www.lincolnelectric.ca/knowledge/articles/content/gmaw.asp
