Overlap Welding: What is it?

One of the primary purposes of welding is to prevent the development of defects in a larger structure. A reason why so many different types of welds exist is to correct deficiencies that occur in different cuts and thicknesses of metal. But welds themselves aren't immune to flaws, and if you're not careful, your weld can do more harm than good.

The most common type of weld defect is called overlap welding. Unlike other flaws, it doesn't have much of a negative impact on functionality. However, it can hurt your projects in different ways.

We designed this post to help you avoid making the common mistake of overlap welding. We'll look closely at the causes and best practices for avoiding them. Keep reading to learn how to improve the quality of your welds.

What is Overlap Welding?

Overlap welding occurs when filler doesn't mix properly with the welded metals. As a result, the excess filler overflows from the top of the weld, creating a noticeable bump on the surface. Despite the uneven appearance, the weld isn't much weaker for overfilling.

You should be concerned with overlap welding for two reasons. First, it creates an uneven, haphazard appearance. Second, the extra filling wastes welding material, costing you money.

Removing welded overlap isn't impossible, but it isn't very easy. It takes a lot of time and skill, and even then, removal risks causing more damage to the welded pieces. Therefore, learning to avoid this mistake is much more practical than correcting it after the fact.

Understanding the different ways this can happen will help you grow as a welder. Four common mistakes lead to overlap welding. We've outlined each one below with simple ways to avoid making them.

1. Poor Metal Preparation

Every piece of metal you weld needs to be handled and prepared carefully. Whatever edges or surfaces you plan on welding need to be even and clear of debris before you begin. Likewise, you must be sure that the pieces are aligned appropriately.

If parts are uneven or misaligned, your welding material will naturally overflow. The easiest way to prevent this is to spend more time carefully ensuring the quality of your prep work. The adage "measure twice, cut one" is as accurate to welding as it is to woodworking.

2. Slow Welding Speed

Weld speed has nothing to do with your tools. Instead, it's how long you, as the welder, take to complete a weld. There's a calculation to determine your precise speed (specifically, the length of a weld divided by the time it takes to achieve it), but knowing your specific weld speed isn't as important as recognizing that you're going too slow.

The slower you are, the more material will fill the weld. As important as accuracy is, being tedious risks using too much and causing an overflow. But because going too fast creates problems too, you have to find the right middle ground.

One way to approach this is to speed up when you think you're at risk of overlap. Changing gears like this won't negatively impact the overall quality of the weld. However, it's worth practicing speed changes in your downtime to recognize the correct speeds and when they are necessary.

3. Incorrect Amperage Speed

At the heart of welding is the use of electrical currents to create intense heat. Amperage is the setting that controls the speed of your current, which affects how fast the material deposits into welds. Therefore, understanding amperage and its variables is crucial to getting a clean weld.

A significant cause of overlap welding is setting amperage too high. The welding material will flow with less control if the current is too fast. Not only will it overflow, but it can splash, leaving deposits across the metal or your workstation.

Selecting the proper amperage depends on the type of joint you're making, the material you're using, and the weld measurements. You can compare these factors to charts online to find the appropriate amperage for your project. Once you've found the setting that's right for you, try a few test runs just to make sure.

The more you weld, the easier it becomes to recognize which amperage settings you should use. In addition to overflow, your electrode offers visual cues that your settings may be off. For example, the current is likely moving too fast if it's glowing brightly.

4. Incorrect Electrode Use

The electrode is the most important part of welding, so naturally, its misuse causes more problems than anything else. Therefore, the electrode's size and angle are vital factors you must be aware of. If misunderstood, you're likely to experience overlap welding or other defects.

Angle is crucial because it determines how the electrode will penetrate the metal. In addition, angle controls how much welding material will fill the weld bead. So if yours isn't appropriate for the task, the risk of overflow increases significantly.

You can avoid this issue by watching how the welding material fills both sides of the bead. If both sides don't fill evenly, it's a sign that you need to adjust your angle.

The size of your electrode matters because it is the filler: a larger electrode results in more fill. Knowing which sized electrode fits your job can be tricky, but you can find guides online that make it easier. With experience recognizing which size to use will become second nature to you.

Meet Your Welding Needs with Engineered Mechanical Systems

Avoiding overlap welding will save you money and give your projects a more professional look. But other defects can be much more damaging to your welds. Without reliable and trustworthy experience, it can be challenging to get past these mistakes and make progress.

That's why you need Engineered Mechanical Systems on your side.

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