All You Need to Know About Flash Welder

Posted on Jan 13, 2021

Flash Welder

Flash welders, similar to another electric resistance welding (ERW) machines, rely on electrodes and heat generated from resistance to current as well as weld force that converts from predetermined pressure.

What Is a Flash Welder?

A flash welder is a resistance welding machine that utilizes flash action and resistance to electric current, in order to fuse multiple metal pieces together, forming a permanent connection among metal sheets. Flash welders, similar to another electric resistance welding (ERW) machines, rely on electrodes and heat generated from resistance to current as well as weld force that converts from predetermined pressure. The flash welder is also known as a flash butt welding machine or flash resistance welding machine.

Electric resistance welding machines come in a wide variety of types. The material, usually metal sheets, are melted at the joint and fused together under heat and pressure. These automatic welding machines including flash welders can benefit the operator to ideally regulate the pressure applied onto the joint, the length of welding time, and the amount of the current that is conveyed to the weld joint. Another benefit of resistance welding machines is that the operator can complete the weld without adding any filler materials to help form the bond, making the welding methods economical and fast.

Compared to other kinds of electric resistance welding methods, flash butt welding utilizes a greatly high level of current density, focusing on a tiny contacting point among the metal sheets. As the flashing process begins in the flash welding machine, additional force will be applied to that welding point to help fabric the metals. At a regulated speed, the clamped parts will be moved closer and create a strong connection in the flash welder. The rapid welding process with the extra force mentioned here can help remove the oxides as well as impurities from the products.


How Does a Flash Welder Work? 

The metal workpieces are typically clamped in a flash welder, carried close together as the electric current is applied to the joint. The stable current which is regulated by the flash welder will form an “arc” among the metal pieces, then expulsion begins, heating the required point. Subsequently, the weld current will be removed. Under the pressure, the joint point will be forged to the required amount. After cooling down, the flash weld products will have weld flash surrounding the weld area, which requires mechanical treatment later, in general. With a flash welder, the metal weld products typically feature strong strengths and fluid-tight.

One key element of a flash welder is the electrode, which is generally made from copper alloys since copper has exceptional heat conductivity and low electrical resistance, making it ideal electrode material for the flash welding process. The nature of the copper ensures that the heat tends to act on the materials instead of the electrode itself. Every time a welding cycle is finished, the electrodes are cooled by the water that flows through them and other conductive elements in flash welding machines.

:: Read more: What Is a Flash Welder?


Flash Time and Upset Time

Flash time of the flash welding operations in the welding machine is one of the important parameters that may affect the product quality. Flash time refers to the amount of time in which the arc is present during the welding process, while the term upset time refers to the time that the metal sheets are pressed together. The flash time should be sufficiently long to fully heat the materials before they are fused together. However, flash time cannot be too long, or the base material will be melted away, creating poor weld. 

As for the upset time, it is essential for forming the required mechanical properties of the final product. Any impurities in the base materials will be pressed out, forming an ideal weld during the critical amount of time that the metal sheets are pressed together. In the cases that the upset time in the flash welder is too short, the impurity remaining in the materials will lead to a defective product. The upset time is also vital to the strength of the weld products created by a flash welding machine. If it is not long enough that allows sufficient and ideal coalescence of multiple pieces, the materials may not fully bond together.


Applications of Flash Welder

When it comes to the applications of flash butt welding, the capability of the flash welder that can fuse various metals with basic parameter settings and the rapid welding operations, making the equipment extremely flexible in usage and popular across industries. Wheel rims are typically produced using flash welding processes and the rims manufactured through this reliable way do not leak air on modern cars and trucks. Flash welder is also widely used in the metal building industry to enhance the length of the angle iron, which is utilized to fuse joints.


● Aluminum industry: 

Another advantage of flash welding is the ability to handle and fuse dissimilar metals including non-ferrous metals together. Non-ferrous metals refer to the metals that do not contain iron, including aluminum, copper, lead, nickel, and zinc. The aluminum industry prefers flash welding machines to fuse aluminum, steel, and copper through the current conductor “busbar”. Consists of steel, copper, and aluminum, the products have ideal strength, conductivity but are cost-efficient.


● Rail Industry: 

The advantages of the flash welding machine allow high manganese steel products like switches and crossings to be efficiently fused to steel railroad, sometimes inserting stainless steel. Utilizing flash welding, the mechanical properties of the rails, as well as the crossings intact, can be ideally maintained. 
Typically, flash butt welding machines are frequently used to produce long welded rails, continuous welded rail which is specially used on high-speed railroads. 

Compared to the mechanically-joined rails, the products created by the flash welding process are much smoother due to the elimination of gaps between the sections. This also reduces the rail wear and lengthens the intervals of inspections and maintenance of the railroads.


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