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What is a Lap Joint Weld?

Posted on September-09-2022

A lap joint is one of the five different types of welding joints. It is most commonly used when joining two different metals that have different levels of thickness. The ‘lap’ reflects the overlapping pattern that is formed when the two metals are joined together. The thickness of the two metals is what determines the amount of overlap needed, the thicker the metal, the more overlap required.

A lap weld can be made on one or both sides, depending on how strong you need the weld to be. You will often find this type of welding on sheet metals as it is rarely used on thicker materials.

Where would you find a lap joint weld?

Here are some examples of where you will most commonly find lap joint welds:
– Laying of pipelines and railway tracks
– Fabrication of sheet metal
– Car and aircraft industries
– Shipbuilding
– Building structures

When should you use a lap joint over a butt joint?

When you are choosing between using a lap joint or a butt joint there are a few things to consider. A butt joint will result in a contour that is more flush and will result in the workpieces being in the same plane. Whereas lap joints will result in a more noticeable contour that will not be flush. However, lap joints will provide more strength in higher stressed areas.

How do I get a good lap joint weld?

– Make sure there are no gaps between the two metals, make them as flush as possible.
– Distortion and burn through can be avoided by reducing the amperage and using a faster travel speed.
– For additional rigidity, weld both sides of the overlapping metals.
– If you are welding thicker materials, create a larger overlap between the two metals.

Advantages of Lap Joints

– Easy to prepare as it does not require the cut faces to be parallel or perfectly flat.
– It is useful for joining thin metals such as diaphragms and foils.
– The metals do not need to be the same level of thickness to be joined.
– It can be formed between two metals that are dissimilar e.g. aluminium and copper.

Disadvantages of Lap Joints

– The overlap caused can be undesirable for mechanical or aesthetic reasons.
– If the wrong welding speed is used cracks and cavity defects can happen.
– The weld can be less rigid than the metals used because it can act as a pivot.
– It can retain moisture which may cause fatigue cracking and corrosion on the shielded areas.
– In some cases, there may be lower levels of tensile strength.

Arc Welding Services

We supply a wide range of welding equipment, tools and supplies in Birmingham and the surrounding areas. With over 40 years of experience, we have worked with major clients such as British Rail and Rolls Royce. Whether you are looking for new, used or to hire welding equipment, Arc Welding is here to help.

If you would like to know more about our services, get in touch with our team today. Contact us on 0121 327 2249 or complete our online contact form and our team will be in touch as soon as possible.

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