What Is a Longitudinal Welding Machine?

Posted on Apr 22, 2021

Longitudinal Welding Machine

A longitudinal welding machine, which is also called a longitudinal seam welder or resistance seam welding machine, is designed for welding faying surfaces like metal sheets together.

What Is a Longitudinal Welding Machine?

A longitudinal welding machine, which is also called a longitudinal seam welder or resistance seam welding machine, is designed for welding faying surfaces like metal sheets together. Longitudinal welding machines can consistently join similar or dissimilar metal materials and press them with generated heat. The seam welding process in longitudinal welding machines is a type of electric resistance welding. Electric resistance welding can be subdivided into 4 types: resistance spot welding, resistance projection welding, resistance seam welding, and resistance butt welding. More features of electric resistance welding (ERW) will be discussed later.

The welding process in longitudinal seam welder is called seam welding, the seam here can be an overlap welding joint or a butt welding joint. The seam welding process begins at one end. Typically, longitudinal welding machines perform the metal sheets fabrication progressively and also automatically. Resistant seam welding is the most common method among various electric resistance welding manners. The welding in a longitudinal welding machine is significantly durable, the reason lies in the seam being forged because of the heat and also the pressure applied. The welded joints that are created by longitudinal seam welders will typically become stronger than the original and base metal materials. The common applications of longitudinal welding machines are in the mass manufacturing of round and rectangular steel tubing and metal sheets, for example, exhaust and fire extinguisher production.

What Are Welding and ERM?

The term welding refers to the industrial process that fuses and fabricates the metals or thermoplastics parts together. Many welding manners require a high-temperature environment to perform welding because the materials have to be melted to connect. There are also other styles of welding, like friction welding, which can perform the metal joining at room temperature. The energy sources of different welding methods define the types and the efficiencies, which include electrical, chemical, frictions, lasers, ultrasounds, and so on.

Among a wide variety of welding methods, longitudinal seam welding is one type of ERW, which is the acronym of electric resistance welding. Electric resistance welding permanently fuses the metals together by heating and melting at the joint with the electric current. Typically, resistance welding is efficient and creates little pollution, however, the suitable applications are limited to thinner materials.

:: Read more: Why Seam Welders are underrated

How Does a Longitudinal Welding Machine Work?

When two or more metal sheets or other kinds of workpieces are formed and pressed together, the surface irregularities generate the electrical resistance in the gap, allowing the metal materials to be heated up and molten at the seam, which is also called joint. The resistance mentioned here in the seam welding process is also known as contact resistance. The current in the welding system is significant to the longitudinal welding machine. The efficiency and the amount of heat created at the joint rely on the magnitude where currents pass through. Similar to resistance spot welding, resistance seam welding requires copper electrodes, too. The welding process typically uses two electrodes which are disc-shaped and spin while the metal passes through the gap between them. In this condition, the copper electrodes can maintain consistent contact with the metals in order to perform durable welds, they can also move or support the movement of the metals in the longitudinal welding machine.

When it comes to the power source, in a longitudinal welding machine, there is a transformer providing energy to the welding joint in the form of high current altering current and low voltage. The seams (joints) of the metal parts have high electrical resistance, which is the areas that are intended to heat, melt and fuse. Then, the semi-molten area on the sheet surfaces will also be applied to the set pressure and finally form the fusion band, completing the permanent, uniform welded connection. Many longitudinal welding machines utilize the water cooling units to cool down the copper electrodes as well as the transformer and assemblies since the heat will consistently be generated in the seam welding process.

There are 2 modes in longitudinal seam welding, which are the intermittent mode and the continuous mode. In continuous mode, the wheels will work constantly while the wheels work in another mode are capable of moving to the commanded point and produce each weld. 

Benefits of Longitudinal Welding Machine

For starters, the longitudinal seam welder requires no tack welding, it can easily perform the metal fabrication of steel tubes or flat materials. The welder provides automated welding and can be used in a wide range of applications, including the production of boiler and gas cylinders. With the longitudinal seam welding machine, there are many available methods to be applied in the welding process, including MIG, TIG, plasma, laser, and so on. The welders are suitable for a large range of metal materials, such as stainless steel, thin steel, aluminum, brass, copper, lead, zinc, and so on. When performing linear seam welding, the longitudinal seam welding machine eliminates the need for start or end weld craters, the entire length of the joint is uniform, in addition, the coloration of stainless steel is also eliminated in the welder.

The Disadvantage of Longitudinal Seam Welding Machine

Although longitudinal seam welding is efficient and most commonly used, there are still some drawbacks. For instance, only straight welding lines or uniformly curved lines are available in longitudinal seam welders because of the roller design. Also, there are limitations with respect to the thickness of metal sheets. The longitudinal welding machine might become inefficient while the thickness of single metal sheets reaches 3mm.

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