Practice Quiz On Electric Welding

The submerged arc process is characterized by deep penetration, high welding current, and exceptionally smooth beads. Deep penetration refers to the ability of the process to create welds that penetrate deeply into the base material, resulting in strong and durable joints. High welding current is necessary to generate the heat required for the process and ensure proper fusion of the metal. Additionally, the submerged arc process produces exceptionally smooth beads, which is desirable for aesthetic reasons and indicates a high-quality weld. Therefore, all of the given options accurately describe the characteristics of the submerged arc process.

The MIG welding process is becoming increasingly popular in the welding industry because it offers both easy operation and a high metal deposit rate. This means that it is relatively simple to use and provides a fast and efficient way to deposit metal onto the workpiece. Additionally, MIG welding can be used with both ferrous and non-ferrous metals, making it versatile and suitable for a wide range of applications.

Spot welding is a process in which two pieces of metal are joined together by applying heat and pressure at a specific spot. The heat is generated by passing an electric current through the metal, causing resistance and generating heat. This heat softens the metal, allowing it to be joined together. Additionally, the application of forging pressure helps to ensure a strong and secure bond between the two pieces of metal. Therefore, the correct answer is the generation of heat and application of forging pressure.

Projection welding is a mass production form of spot welding. In projection welding, the joint surfaces are designed with small projections or bumps that concentrate the heat and pressure at specific points, allowing for efficient and precise welding. This method is commonly used in industries where high volumes of welds need to be made quickly and accurately, such as automotive manufacturing.

The overhead welding position is considered the most hazardous because it requires the welder to work with their arms raised above their head, which can lead to fatigue and strain. Additionally, there is an increased risk of molten metal and sparks falling on the welder, which can cause burns and other injuries. The overhead position also presents challenges in terms of visibility and access, making it more difficult to achieve a high-quality weld. Overall, the overhead welding position poses the greatest risk to the welder's safety and requires extra caution and protective measures.

In electrode-positive welding, two-thirds of the total heat is produced at the electrode. This means that the majority of the heat generated during the welding process is concentrated at the electrode, rather than being evenly distributed throughout the welding area. This concentration of heat at the electrode allows for better control and precision in the welding process, as the heat can be focused on the specific area that needs to be welded.

A weld bead of wineglass design is produced in plasma arc welding. In plasma arc welding, an electric arc is formed between a tungsten electrode and the workpiece. The high temperature of the arc ionizes the gas, creating a plasma that can reach temperatures of up to 30,000 degrees Celsius. This intense heat allows for precise control and manipulation of the weld pool, resulting in a wineglass-shaped bead.

A high open-circuit voltage is necessary in arc welding because it provides the necessary energy to initiate and maintain the arc between the coated electrodes. This voltage helps to establish a stable and consistent arc, allowing for effective welding. Without a high open-circuit voltage, the arc may not be able to form or may be unstable, resulting in poor welding quality.

Welding requires a high amount of current to generate the heat needed to melt the metals being joined. Drawing such heavy currents directly from the supply mains would be impractical because it could overload the electrical system and cause damage. Therefore, it is more practical and safer to use welding machines that are designed to handle the high currents required for welding.

High temperature metals like columbium have a high melting point and are difficult to weld using conventional methods like flash, MIG, or TIG welding. However, electron beam welding is a suitable method for welding high temperature metals as it utilizes a high-energy electron beam to create a localized heat source, allowing for precise and efficient welding of these metals.

In DCSP welding, the base metal penetration is deep. This means that the welding process allows for a thorough and deep fusion between the base metal and the filler material. This deep penetration ensures a strong and durable weld joint, as the base metal and filler material are effectively joined together.

Electric resistance seam welding uses disc electrodes. Disc electrodes are commonly used in this type of welding because they provide a larger contact area with the workpiece, resulting in a more efficient and consistent welding process. The disc shape allows for better heat distribution and conductivity, ensuring a strong and reliable weld seam. Pointed, flat, and domed electrodes may be used in other types of welding processes, but for electric resistance seam welding, disc electrodes are the most suitable choice.

An AC welding machine cannot be used for MIG welding because MIG welding requires a direct current (DC) power source. MIG welding uses a consumable electrode wire that is continuously fed through a welding gun, and the DC power source provides the necessary electrical current to create the arc and melt the wire. AC welding machines, on the other hand, produce an alternating current that is not suitable for MIG welding.

Using AC welding machines can help avoid arc blow in electrical welding. Arc blow is a phenomenon that occurs when the welding arc is deflected or deviated from its intended path due to magnetic forces. AC welding machines alternate the polarity of the welding current, which helps to minimize the effects of magnetic forces on the arc. By using AC welding machines, the welder can maintain better control over the welding arc and prevent it from being deflected, resulting in a more accurate and precise weld.

The major disadvantage of carbon arc welding is the occurrence of blow holes. Blow holes are cavities or voids that form in the weld due to the release of gases during the welding process. These blow holes can weaken the weld joint and compromise its integrity.

MIG welding uses consumable electrodes, which means that the electrode itself melts and becomes part of the weld. This eliminates the need for a separate flux material, as the electrode provides the necessary protection from atmospheric contamination. Additionally, because the electrode is consumed during the welding process, there is no need for post-weld cleansing.

In atomic hydrogen welding, AC supply is used. This is because AC supply allows for better control and stability of the welding process. It ensures a consistent and stable arc, which is essential for achieving high-quality welds. AC supply also helps in reducing the electrode wear and increasing their lifespan. Therefore, the electrodes used in atomic hydrogen welding are long-lived due to the use of AC supply.

In the process of electroslag welding, theoretically there is no upper limit to the thickness of weld lead. This is because electroslag welding is specifically designed for welding thick materials. It utilizes a consumable electrode that is continuously fed into the joint, allowing for the creation of large and deep welds. Unlike other welding processes, electroslag welding can handle extremely thick materials without compromising the quality of the weld. Therefore, there is no theoretical limit to the thickness of weld lead in electroslag welding.

DCRP stands for Direct Current Reverse Polarity, which is the major power supply used in MIG welding. In DCRP, the electrode is connected to the positive terminal of the power source, while the workpiece is connected to the negative terminal. This configuration allows for better control over the welding process, as it provides deeper penetration and higher welding speeds. It also helps to reduce spatter and improve the overall quality of the weld. Therefore, DCRP is the preferred power supply for MIG welding.

Electrode coating is used to improve bead quality in welding. The coating on the electrode helps to control the weld pool and the flow of molten metal, resulting in a smoother and more consistent weld bead. It also provides protection against atmospheric contamination by creating a shield around the weld pool, preventing the formation of defects such as porosity or inclusions. By improving the quality of the weld bead, electrode coating ensures a stronger and more reliable weld joint.