Shielded Metal Arc Welding (SMAW) is a manual arc welding process. The metal rod is covered with flux which provides the shielding to protect the weld. Given that SMAW is tough to master as it needs practice and experience, it could be difficult for beginners.
Here are some tips for beginners to handle SMAW welding like a pro.
Choose SMAW-Friendly Steel
Low-alloy and carbon steels can crack easily if they do not have the right mix of silicon and sulphur content. Similarly, steels which have high sulphur and phosphorous content are also not suitable for production welding. Hence, select steels which can be welded at fast speeds and have lower cracking tendency.
Prevent Buildup and Overwelding
Surplus buildup is expensive in terms of time and material. Moreover, it contributes hardly anything to weld strength. It also increases distortion. Hence, make sure that the fillets have equal legs and bead surface is as flat as possible. Ideally, buildup should not exceed 1/16 inches.
Select the Right Electrode Size
Large electrodes are suitable for welding which require high currents for high deposition rates. Hence, it is recommended to use the largest electrode, depending on your application and consistency with good weld quality.
Clean the Joint Before Welding
Removal of excess grease, paint, oil, rust, moisture and scale is necessary to prevent porosity and obtain the ideal weld travel speed. In case you are unable to clean these elements, use types of electrodes that can penetrate contaminants and deeply into the base metal.
Match the Joint Position and Electrode with Metal
The position of joint is responsible for finished weld quality. If you overweld or create a weld that is bigger than necessary for joint strength, then it can cause burn-through. Hence, take due care to match the joint position and electrode with metal during SMAW welding.
Adhere to the Principles for Joint Geometry and Fit-Up
Keep in mind the fast welding speed and good weld quality while choosing weld dimensions. The joint geometry follows some basic principles:
Fit-up and the entire joint must be consistent with each other.
Use a bevel that assists in good bead shape and penetration.
Choose a root opening which is consistent with the diameter of electrode.
Use a root face or a back up strip for fast welding and high quality.
As far as troubleshooting weld defects are concerned, here are some ways to correct them:
We hope these guidelines, advice and troubleshooting tips will help you to work your way through SMAW welding.