Sheet Metal Welding: Common Methods and Techniques of Welding

After cutting metal sheets to the right size, they must be joined together to form the desired shape and fulfil the requirements. Therefore, metal welding is a critical part of manufacturing metal products. There are various methods of metal welding. So, do you know which method is best suited for your business needs?

This article describes the different metal welding methods, along with their benefits and uses. In addition, it provides important tips for welding thin metal sheets for optimal results.

6 Methods of Metal Welding

Next, let’s take a closer look at the different methods of welding sheet metal together.

MIG Welding

Metal inert gas (MIG) welding is also known as gas metal arc welding. It consists of feeding a continuous solid wire electrode into a weld pool using a torch. The molten wire in the pool then causes the metal parts to stick together. In addition, the gas in the torch protects the weld pool from airborne contamination.

MIG welding provides high strength and quality for most sheet metals such as aluminium, steel, and stainless steel. As a result, this welding method is the preferred choice in the automotive manufacturing and home improvement industries. It does not require any expensive equipment and hence is an economical method.

TIG Welding

Tungsten inert gas (TIG) welding is a type of arc welding. It uses a non-consumable tungsten electrode for welding under DC or AC. Like MIG welding, it uses an inert shielding gas to protect against atmospheric contaminants and oxidation of the electrode and molten pool, such as argon or helium.

TIG welding is suitable for welding non-ferrous metals such as aluminium, titanium, copper, nickel, magnesium, and chromium. It is an effective method for the aviation and aerospace industries. In addition, it is perfect for making motorcycle frames, doors, and feeder frames.

This welding method gives workers better control, resulting in clean, strong welds. However, this method of welding is time-consuming and requires special skills on the part of the welder.

Read More: difference between mig and tig welding

Stick Welding

Welding with welding rods is also known as shielded metal arc welding. It is a manual arc welding process that uses a flux-covered welding rod as the electrode. The current from the welding power source creates an arc between the weld metal and the electrode. It is suitable for welding hard metals such as iron and steel.

Moreover, this welding process does not require any shielding gas. When heat is generated, it breaks down the coating on the electrode and forms a layer of slag that keeps the weld pool free from contamination. In addition, it is easy to transport due to its compact equipment. Therefore, this welding process is very convenient. The electrode welding process is very popular in the construction, shipbuilding, and steel-making industries.

Plasma Arc Welding

Plasma arc welding is a method of welding metal using a high-temperature plasma arc. This welding process is similar to TIG welding because both use tungsten electrodes. However, plasma arc welding uses a smaller arc and the electrode can be placed on the body of the torch. Pressurized gas then produces a hot plasma that melts the metals, joining them together to form a strong weld.

This welding method consumes little electricity and operates quickly. And it makes precise welds, so it is commonly used in the aerospace and marine industries. Like TIG welding, plasma arc welding does not require additional material to fill the joint. In addition, plasma arc welding produces high-quality welds that do not require much finishing.

Electron Beam and Laser Welding

Laser and electron beam welding uses lasers and electron beams to heat metal parts and weld them together. Unlike other welding processes, this welding method requires advanced machines or automated robots. The laser beam can be focused on a very small amount of material for precise welding. As a result, it is a very precise welding method that is ideal for small, delicate parts.

It is also suitable for welding strong metals such as carbon steel, titanium, stainless steel, and aluminium. On the other hand, this method is also suitable for thermoplastics. Laser welding produces aesthetically pleasing products and minimizes post-production handling.

Gas welding

Gas welding is a traditional welding method that uses heat. It consists of welding pieces of metal together using the heat generated by the combustion of fuel (gasoline), oxygen, or oxyacetylene. Burning these fuels creates a very hot flame which melts the metal surfaces as they are welded together.

This technique remains one of the most commonly used welding methods in industry. It can be used on a wide range of metals, including ferrous and non-ferrous metals. In addition, it is effective in welding pipes and tubes as well as fixing ventilation and air conditioning systems.

Unlike many other welding methods, this method does not require a power source. Gas welding is portable, cost-effective, and does not require expert help.

How to Choose a Metal Welding Process?

The following are the types of surfaces that may be encountered when welding sheet metal and the best way to deal with them.

Flat surfaces

Flat surface welding is welding on a flat surface. The welder works from the top of the weld joint, using gravity to help move the molten metal. To make a good weld on a flat surface, the welder should hold the weld head at a 45-degree angle to the metal. In addition, the welder needs to aim the flame at the point where the two pieces of metal meet.

MIG and TIG welding work best on flat surfaces. Wire feed and airflow work very well on a flat surface.

Horizontal Surfaces

For this horizontal configuration, the sheet metal is placed flat. However, it is usually welded in two ways.

• Fillet Weld: The weld is made where the flat surface meets the top of the vertical surface. The joint area appears to be two pieces of metal that are perpendicular to each other and joined together in an “L” shape.
• Bevel Weld: The weld surface is located in a vertical plane. Both pieces of metal to be welded are in the same plane.

For horizontal surfaces, it is difficult to achieve a perfect balance between TIG and MIG welding. Stick welding, on the other hand, is ideally suited for working on horizontal surfaces.

Vertical Surfaces

This type of welding tube is upright and the upright surface faces the welder. When welding, the liquid metal usually flows downwards and collects in one place. Therefore, the welder needs to control the way the metal flows. This means holding the torch at 45 degrees to the sheet metal and keeping the electrode between the flame and the weld pool.

Stick welding is the best process for welding vertical surfaces. The welder usually varies the welding angle to make it appear flat or horizontal to make the job easier.

Overhead Surfaces

Welding on overhead objects is the most difficult. As the name implies, this means welding a workpiece above your head. When you try to weld, the molten metal tends to fall off. To make welding at height easier, reduce the size of the weld pool. Make sure you add enough filler material to get a strong weld.

For this setup, stick welding is the best method. Also, overhead welding is not common in customized sheet metal shops.

Tips for Welding Sheet Metal

When performing metal welding, the goal is to ensure that the weld area is strong enough for the application. The following are some simple tips to remember when performing metal welding.

Selection of Filler Metal

It is important to select a filler metal that matches the strength and properties of the project. This is because the filler must be thinner than the sheet metal. If you are welding thin metal 1 mm thick, then 0.6 mm filler is the best choice.

Thinner wires require less heat to melt. This means less risk of overheating and better welding results. In addition, choosing the right filler metal helps to reduce the chances of rust, cracks, and other problems.

Use of Skip Welding Techniques

The skip welding technique consists of using a series of seams or short welds at critical points to hold a thin sheet of metal. After it has cooled for a few minutes, the welder can begin to weld the areas that were previously missed.

Skip welding prevents the metal from bending or twisting due to uneven heat. Also, do not move the torch back and forth while welding. This will generate too much heat. Instead, move the torch quickly in a straight line.

Using Spot Welding Techniques

Spot welding is a good way to help prevent overheating and burn-through. This welding technique uses a small temporary weld to hold the metal pieces together until they are fully welded. To prevent burn-through, it is important to ensure that the pieces are held together with a 1 mm gap in between. Small spot welds are then made until the seam is completely covered.

Use of Fine Wire

When using solid wire electrodes for MIG welding, always choose the finest wire available. The use of fine wire helps the welder to have better control. And because fewer deposits are produced, it is easier to correct errors. In addition, finer wire requires less heat to melt. As a result, excessive heat is less of a problem.

Typically, 0.023- or 0.024-inch wire is recommended for working with thin and light sheet metal. However, when welding metal 18 inches or thicker, 0.030-inch wire may be the best choice.

Using a Small Electrode

Be sure to use an electrode rod that is thinner than the metal. In addition, electrodes smaller than ⅛ inch should be used. This is because smaller electrodes have less heat and draw less current, which helps prevent burn-through. This allows the electrode to be ground smaller to create a concentrated arc.

Clamping the Backing Plate

Clamping the backing rod to the metal helps to cool it more quickly than allowing the metal to cool on its own. The support rod absorbs heat from the metal and helps prevent the metal from warping or burning through.

Metal rods are usually made of copper or aluminium because they conduct heat well. In addition, it is necessary to ensure that the support rods are securely fastened to the workpiece so that heat can be properly transferred.

Use of High Argon-based Shielding Gas

Protective gases with high argon content should be used when welding. For example, a common mixture of argon and carbon dioxide is 75 to 25.

A shielding gas with a high argon content is chosen because argon produces less heat. In addition, pure argon may be required for protection when TIG or MIG welding aluminium.

Assembly and Joint Design

Welding thin sheet metal is a challenge. Because there is little room for error, a tight and solid fit is required. The gap between the two pieces of metal should be small to avoid burn-through, as the holes absorb heat.

In addition, welders should measure twice and then cut once. Sometimes, you may need to change the form of the joint so that it can withstand more heat.

Summarizing

Do you need quality welding services for unique sheet metal work? Do you need welded sheet metal for your industrial needs? Yonglihao Machinery can provide you with the services you need. We can provide quality services in the areas of welding, laser cutting, and CNC machining.

Yonglihao Machinery can provide skilled sheet metal services. Simply send in your design files and you will receive a free analysis of your sheet metal part fabrication. We are committed to providing quality service at reasonable prices with fast turnaround times.

FAQ

Which Welding Method is Most Suitable for Thin M1etals?

TIG welding is the best method for welding thin metal parts. This is because TIG welding is very precise and concentrates on the area to be welded. As a result, the surface of the welded part is smooth and delicate.

Can I MIG Weld Aluminum Using AC or DC Power?

Both AC and DC MIG welding can be used for aluminium welding. DC welding is a common type of MIG welding and is much faster. This is because it does not require the use of both AC and DC tools.

What is the Thinnest Sheet Metal that Can Be Welded?

Welding very thin metals requires skilled workers who carefully control the amount of heat used. With proper heat control, you can use MIG welding to weld sheet metal as thin as 0.8 millimetres. In addition, TIG welding can weld sheet metal as thin as 0.6 millimetres or even thinner.