The welding process which is used for making continuous weld while two pieces to be joined are overlapped and placed between two revolving electrodes, is called
Seam welding
Welding Process Fundamentals
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material (the weld pool) that cools to a strong joint, but some welding processes do not involve melting (like solid-state welding). The question describes a specific type of resistance welding, which relies on heat generated by electrical resistance to join materials.
Seam Welding: Continuous Joint Creation
The welding process described in the question, which is used for making a continuous weld while two pieces to be joined are overlapped and placed between two revolving electrodes, is called Seam welding.
- Continuous Weld: Unlike spot welding which creates discrete points, seam welding produces a continuous, often leak-tight, joint.
- Overlapped Pieces: Similar to spot welding, the parts to be joined are placed in an overlapping configuration.
- Revolving Electrodes: Instead of stationary electrodes, seam welding uses two wheel-shaped or disc-shaped electrodes that rotate. The workpieces pass between these rotating electrodes.
- Mechanism: As the workpieces move between the revolving electrodes, intermittent or continuous current pulses are applied. This creates a series of overlapping spot welds, which fuse together to form a strong, continuous seam. The rotation of the electrodes provides the necessary pressure and transports the material through the welding zone.
- Applications: Seam welding is frequently used where leak-tight joints are required, such as in fuel tanks, radiators, exhaust systems, and general sheet metal fabrication.
Comparing Welding Processes
To understand why Seam welding is the correct answer, let's briefly compare it with the other common welding processes listed in the options:
| Welding Process | Key Characteristics | Why it's Different from Seam Welding |
|---|---|---|
| Seam Welding | Uses revolving electrodes to create a continuous weld on overlapped pieces. Forms a series of overlapping spot welds. | This matches the description exactly. |
| Spot Welding | Uses two stationary electrodes to create discrete, individual spot welds at specific points. Pieces are overlapped. | Does not create a continuous weld and uses stationary electrodes, not revolving electrodes. |
| Projection Welding | Resistance welding where one or both workpieces have small projections or embossments. Heat is concentrated at these projections, and multiple welds can be made simultaneously. | Does not use revolving electrodes and relies on pre-formed projections, not a continuous run between wheels. |
| Flash Welding | A resistance butt welding process where parts are clamped, brought together, and a voltage is applied to create an arc (flash) that melts the ends. Then, an upsetting force is applied to forge the molten ends together. | Primarily used for butt joints (ends touching), not overlapped pieces. Does not use revolving electrodes and is not designed for a continuous weld in the same manner as seam welding. |
Conclusion on Continuous Welding
Based on the detailed description provided in the question—a welding process for making a continuous weld on overlapped pieces using revolving electrodes—Seam welding is the only process that fits all these criteria. It effectively converts a series of resistance spot welds into a single, continuous, and often leak-proof seam, making it distinct from other resistance welding methods like spot, projection, and flash welding.
Important Questions from Welding
To weld metals together, high temperature is required. Such a high temperature is obtained by burning:
Which one of the following is not classified as a fusion welding process?
The material used for coating the electrode is called
When attaching a High-Speed Steel (HSS) cutting insert to a carbon steel tool holder, which joining technique is commonly used to ensure a strong bond without adversely affecting the heat treatment of the HSS?
- What is the primary action of the electrodes during resistance seam welding?
