What Is Resistance Welder?
Resistance Welder is a machine designed for welding metals.
The welding part is sandwiched between two electrodes, and pressure is applied to the metal while passing electrical current through it. Since Joule heat generated by the resistance of the metal to be welded is used, there are various types of welding machines, such as inverter, transistor, and capacitor types, depending on how the current is passed through the electrode. Welding machines are classified into direct spot, indirect spot, series spot, and twin spot, depending on the method of current flow.
Resistance Welders, due to their structure, are mainly used for welding flat objects such as metal plates and pipes. They can be used for a wide range of applications, such as body panels of automobiles and steel frames of buildings. Resistance Welders offer rapid and high-strength welding. However, Resistance Welders may not be suitable for certain materials.
For example, aluminum and stainless steel are difficult to weld efficiently due to their low resistance values. In addition, the heat generated during welding may cause distortion. Therefore, it is also important to note that accurate heating control is necessary.
Uses of Resistance Welders
Resistance Welders are mainly used in factory production lines where welding is required. For example, they are used to weld parts of automobile bodies and to join the chassis of home appliances. They are also used at construction sites to weld steel frames for construction.
Resistance Welders are characterized by their high welding speed and low consumable parts, making them ideal for automation in mass production. They are frequently used in mass production lines. In recent years, Resistance Welders that are compatible with automation have been developed, and are now in use in the manufacturing processes of automobiles and home appliances.
When selecting a Resistance Welder, it is necessary to consider cost factors such as electricity consumption, electricity and equipment costs, impact on other electrical equipment, the type and thickness of the metal to be welded, and welding quality. Resistance Welders must also be selected to suit the application, as the accuracy and speed of welding, as well as the range of welding that can be performed, vary depending on the installation method.
Principle of Resistance Welder
Resistance Welders consist of four elements: a power supply, a transformer, a pressure control device, and an electrode. The current supplied from the power source is converted to a high current by the transformer and flows to the electrode. The electrode is pressed against the metal by the pressure controller, and the current flowing through the metal generates Joule heat, enabling metal-to-metal welding.
There are three types of Resistance Welders: Single-Phase AC, Inverter, and Capacitor. The single-phase AC type is widely used for general purposes due to its simplicity and cost-effectiveness. The inverter type, on the other hand, uses an inverter to convert AC power into DC for welding, enabling high-quality welding and is used for welding aluminum and plated steel plates. The capacitor type stores electricity in a capacitor and releases it all at once, thus producing a large current. It is suitable for short-duration welding, but may not be ideal for continuous welding due to the time required for storing electricity.
Other Information on Resistance Welders
How to Use Resistance Welder
The metal to be welded is placed between the anode and cathode. Instantaneously, it undergoes intense heating and welding as a discharge of electricity occurs while pressure is applied between the electrodes. This discharge is typically initiated using a foot switch or push switch. The time of discharge needs to be adjusted in advance according to the type and thickness of the metal to be welded.
During test welding, the welding current and time are adjusted to the appropriate level for sufficient weld strength and to prevent excessive burning. Generally, copper and aluminum are difficult to weld with high current flow, so the current should be increased and the time should be set longer.
On the other hand, nichrome wire and steel plate are easy to weld due to their high resistance and can be welded in a short time.