In electric arc welding, the deflection of the arc from the weld point is called:
arc blow
Understanding Arc Blow in Electric Arc Welding
Electric arc welding is a process that uses an electric arc to melt and fuse material at the joint. The arc is typically formed between an electrode and the base material.
During this process, the electric arc should ideally remain directed at the precise point where the weld is being made. However, external factors can sometimes cause the arc to deviate or deflect from this intended path.
What Causes Arc Deflection in Electric Arc Welding?
The most common cause for the deflection of the arc in electric arc welding is the presence of magnetic fields. These magnetic fields can be generated by the welding current itself, especially in DC welding, or by residual magnetism in the base material. The interaction between the welding arc current (which is a moving charge) and these magnetic fields creates a force that pushes the arc away from its intended path.
This phenomenon of the arc deflecting from the weld point due to magnetic forces is known by a specific term in welding.
Analyzing the Given Options
Let's look at the provided options to identify the correct term for this deflection:
- Option 1: arc tail - The arc tail refers to the trailing end of the molten weld pool as the electrode moves along the joint. It is not the term for the deflection of the arc itself.
- Option 2: arc blow - Arc blow is the phenomenon where the welding arc is deflected or blown away from the intended weld joint. This deflection is caused by magnetic forces and fits the description given in the question.
- Option 3: arc suppression - Arc suppression refers to methods or conditions that extinguish or stop the welding arc, often intentionally, such as at the end of a weld pass, or unintentionally due to poor technique or equipment issues. It is not related to the deflection of an active arc.
- Option 4: arc loss - Arc loss is not a standard or widely used technical term in welding to describe arc deflection. While an unstable arc might be difficult to control, 'arc loss' does not specifically describe the physical deflection from the weld point.
Identifying the Correct Term for Arc Deflection
Based on the definitions, the term that accurately describes the deflection of the arc from the weld point in electric arc welding, primarily due to magnetic forces, is arc blow.
Impacts of Arc Blow on Welding Quality
Arc blow is a significant problem in welding as it can lead to various defects, including:
- Lack of fusion or penetration
- Increased spatter
- Porosity
- Undercutting
- Inconsistent weld bead shape
- Difficulty controlling the weld pool
Summary of Terms
To clarify the terms, consider the following:
| Term | Description | Related to Arc Deflection? |
|---|---|---|
| Arc Tail | Trailing end of the molten weld pool | No |
| Arc Blow | Deflection of the arc from the weld point due to magnetic fields | Yes |
| Arc Suppression | Extinguishing or stopping the welding arc | No |
| Arc Loss | Not a standard term for deflection | No |
Therefore, the deflection of the arc from the weld point in electric arc welding is correctly termed arc blow.
Revision Table: Electric Arc Welding Terminology
| Welding Term | Simple Explanation |
|---|---|
| Electric Arc | A sustained electrical discharge between electrode and workpiece, generating heat. |
| Arc Blow | Deflection of the arc due to magnetic forces. |
| Weld Pool | Molten metal area where filler material and base metal are fused. |
| Spatter | Molten metal droplets expelled from the arc or weld pool that solidify around the weld. |
| Lack of Fusion | A welding defect where surfaces are not properly joined. |
Additional Information on Preventing Arc Blow
Understanding the causes of arc blow is the first step to preventing it. Since it's primarily caused by magnetic fields, techniques to control or counteract these fields are used. Some methods include:
- Using AC welding instead of DC welding (AC welding polarity rapidly reverses, cancelling out magnetic effects).
- Using shorter arc lengths.
- Adjusting the ground clamp position (placing it further away from the start or end of the weld).
- Using run-on and run-off tabs.
- Demagnetizing the workpiece before welding.
- Changing the welding technique or travel speed.
Controlling arc blow is essential for producing high-quality welds.
Important Questions from Welding
The flame which contains excess oxygen than theoretical required:
In gas welding, the inclination of the blow pipe with respect to the plate in Leftward welding is-
In resistance welding, the SCR contactor will close during ____
In the flash butt welding:
Carburising flame is used to weld metals like _____.
