Metal fabrication plays a significant role in building metal machines and structures. It is important to produce quality welds, and knowing the factors that affect weld quality will help you. How does speed affect weld quality?
Speed or travel speed is a crucial variable that affects the weld bead size, pattern, and penetration—whether too high or too low, using extremes of travel speed can reduce the quality of your weld.
This article describes the factors that affect the quality of a weld, focusing on how travel speed affects it. I also discuss how to check for welding defects and share tips on what improves the quality of your weld.
What Affects the Quality of a Weld?
Producing quality welds ensures the stability and durability of the structures you contribute to and improves the credibility of your manufacturing or welding business.
When you know the variables that affect the quality of your weld, you can make improvements where necessary. Before looking at what affects weld quality, here are the requirements or features of quality weld products:
- The product provides the strength and functionality that the project requires.
- You finish the program according to the design dimensions accurately, with almost zero distortion.
- The appearance of the weld fits the level required:
- Uniform beads—width, height, and waves.
- No cracks or holes in the bead
- Full penetration in the welds
The variables that affect weld quality include issues with the design, problems with the materials, and welding techniques. The size of the weld, base material, travel speed, filler material, shielding gas, edge preparation, distortion, volts, amps, etc. Below is a description of some variables:
- Distortion
It occurs when welding light-gauge sheet metals, and you can minimize it by using reinforcements.
- Edge preparation
The type of weld and thickness of the metal plates usually determines what edge preparation you will apply. For example, when welding metal plates, you need to consider the proper spacing between edges and joint edge preparation. In contrast, sheet metal melts easily and doesn’t require edge preparation.
- Amperage
It mainly affects the depth of penetration of the base metal and the melt-off rate of the electrode. Amperage controls what lies beneath the surface of the base metal. Too much amperage can cause burn through, and too little produces little penetration.
- Voltage
It has a negligible impact on penetration and helps the weld to wash in and lay flat at the weld’s toes. Voltage mainly controls what you can see above the base material’s surface.
Too little voltage can contribute to a lack of fusion, and too much can cause undercut, concave weld, and a flat weld.
How Does Speed Affect Weld Quality?
Weld quality might mean different things depending on what the client requires. Some engineers consider quality welds to have a strong seal, while quality for others means a consistent weld with pleasing aesthetics.
Travel speed is the speed at which you move the welding gun or torch across the workpiece, and it is measured in millimeters per minute. Together with amperage and voltage, it determines the amount of heat input in arc welding.
Controlling travel speed helps prevent weld defects and ensures good weld penetration. Higher travel speeds do not give the arc enough time to melt the base material adequately, resulting in thin, narrow welds with poor penetration and fusion.
Slow travel speeds can cause excessive weld deposition, which commonly causes cold lapping or a lack of fusion. It can also result in slag inclusions, bun-through, and excessively wide welds.
The type of filler material, welding position, and welding process limit the maximum travel speed capable of producing quality welds. To maximize travel speed while producing quality welds, you must consider working around these factors.
How Do You Check for Welding Defects?
A welding defect is any flaw or anomaly that compromises the usefulness of a weldment (finished product.) On the other hand, weld imperfections disrupt the regular flow of the weld and are easily visible, and an accumulation of weld imperfections results in a weld defect.
Some weld defects are visible, and if you can identify them quickly, you can make adjustments and corrections. Weld defects include:
- Porosity
- Undercut
- Lack of fusion or incomplete fusion
- Slag inclusions
- Lack of penetration or incomplete penetration
- Spatter
- Overlap
Welding tests reveal the defective or weak sections you can correct before sending the material to the field. Two types of weld testing are Destructive Testing and Non-Destructive Testing.
What Can Improve the Quality of My Weld?
Beginners and experienced professionals may make mistakes when welding, but they do not have to happen all the time. High-quality welding processes ensure welding integrity and repeatability,—delivering strong and durable welds consistently.
You have an excellent foundation to produce quality welds with cleanliness, preparation, good welding skills, and an understanding of the materials and gas used. Here are some tips to improve your welds:
- Preparation
Clean your metal surfaces, prepare the edges of the workpieces, and eliminate oxide layers before you start welding. Ensure that it is free from grease, dust, paint, rust, etc.
- Set your gas to the right amount for good penetration. Adjust the flow meter on your welder and constantly check your output levels.
- Clean the nozzle of your weld gun frequently, as spatter can accumulate over time. If it clogs the welding gun, it can restrict the flow of the shielding gas.
- Set your wire speed based on the thickness of the metal and the amperage you are using. If your wire speed is too fast, your welder will produce a popping sound, and if it is too slow, the spray arc from your welder won’t have much sound.
- Decrease the number of passes you make when you weld to decrease the likelihood of porosity, lack of fusion, and inclusions at the toe of the weld.
- Reduce your arc length by keeping your weld tip the right distance from the weld joint and hold your weld gun at the angle that matches the type of weld you are doing. A 45-degree angle works best in most cases.
With practice and patience, your skills will improve, and the quality of your welds too. Remember to follow the proper welding codes and guidelines.
