Projection Welding – The Technique and Uses

Welding is a complex world full of different techniques – all have been developed to match the desired results. Whether the job must be completed by arc welding in a fiery dance or through laser welding with controlled heat, there is bound to be a good method for mold makers needing precision welds of cores and cavities. 

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Projection welding is a type of resistance welding and an interesting process for producing effective control, high weld strength and accuracy.

What is Projection Welding?

Just think of a mini volcano gushing up in the middle of metal. Let us get back to basics, this is what projection welding does — it places a molten zone at the point of requirement welding and brings together two metallic sheets in overlapping fashion. The trick is in a special projection, protuberant fingering or embossing created on one of the sheets. This projection further focuses the electrical current and welding force, producing a quick weld only at desired locations with regards to during welding.

The Power of a Focused Punch

Read on to learn more about the science behind projection welding.

PreparationClean and orient the metal sheets with the projection opposed to that of the opposing sheet so a minimal contact area is obtained.Current – Overlapping metals are then subjected to high amperage current. But, that’s the job of a projection : to serve as a focused spot for the transfer current (unlike flat electrodes in case of spot welding).

Resistance Heating: Since the smaller area of projection has lesser volume, when current encounters resistance at point of contact intense heat is produced with higher intensity. This causes the metal at the tip of projection and in a sheet opposed to it locally heat enough,liquefy. 4. Pressing) By this time, the rolls (3.Glue Application: Finally a force is applied through electrodes to push the sheets together. This pressure is used to drive the material into contact with each other, regulate the size and shape of welds made or enable any oxides or contaminants from the molten metal as it breaks down.

After enough heat is generated and pressure applied the current stops, the molten metal cools down again becoming solid creating a perfect weld between these two sheets.

Benefits of Projection Welding

The main benefit is that it offers a vast number of advantages and most people tend to deal with projection welding because they have already been tried enough in various applications.

The projection contains the weld within predefined boundaries to be formed by the joint design or for placing repetitive patterns (Figure 1).

Focussed Heats enable strong localized welding with minimal heat affected zone to the surrounding area, which restricts distortions in the base metal.

Speed of Production: The quick heat and cool cycle speeds up welding times for applications with large production quantities.

Welding results in Spatters: The process is controlled that creates only smooth and clean welding which will not give off any spatter.

Lesser Electrode Wear: Because of the smaller contact area with a projection, electrode wear in this process is much lesser as compared to spot welding.

Versatile: Resistance projection welding has a versatile application range from thin materials to dissimilar metals, when process parameters are set accordingly.

Areas of Projection Welding

This is one of the many applications in various industries where projection welding has an edge over conventional resistance spot welding. Below is a list examples of the way it can be done

Projection welding is prevalently utilized in the automotive industry to join components with complex geometry such as battery enclosures, instrument panels and body parts

Electronics ManufacturingCreating reliable connections for electrical components such as Circuit Boards and Battery Contacts are vital in Electronics manufacturing. For applications in which precision and control are key, projection welding provides an ideal solution.

Home Appliance Manufacturer: Parts inside appliances such as washing machines and refrigerators often use projection welding to create good tight joints.

Aerospace Industry: Well, since lighter and stronger structures are used in aircraft as a core requirement today, projection welding is generally applied to join thin sheets of high-strength metals.

Construction Industry:Prefabricated metal structures can be made quickly and accurately using the projection welding, which leads to functional connections that are holding well together.

Projection welding tips

Pros and Cons of Projection Welding

Tooling Costs: Tooling, with the required projection design is more expensive to create than in some other welding processes.

Joint accessibility: The probe must be capable of making contact with the electrodes to make visualization accurate, which makes it difficult for intricate joint geometries.Material Thickness – Projection welding is ideal for thin to medium-gauge metals. When it comes to welding thicker materials, you may need specific tools and modes.

Weld The Smart Way

One of the most efficient solutions for this is projection welding to join sheet metals. Given that it is capable of producing good strong and accurate localized welds, this method proves useful in a variety of applications across multiple industries. If you have a project that is in need of fast, accurate and restrained means of joining metal parts using specific weld spots or if your product requires low heat distortion, projection welding might be just the right process for it. Keep in mind you can consult with a trained welding professional that will guide you, and help determine if projection is the right method for your applications.

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