MMAW: Trivia Questions On Manual Metal ARC Welding Process! Quiz

Large electrodes have a higher heat input compared to smaller ones. When used on thin material, this excessive heat can cause the electrode to burn through the parent metal, creating holes. Therefore, it is true that large electrodes can burn holes through thin material.

When metal is in its molten state, it is at a high temperature and in a liquid form. As it cools down to atmospheric temperature, it undergoes a process called contraction or shrinking. This change in temperature causes the metal to change its shape or dimensions, leading to distortion. Therefore, the statement that distortion occurs when the metal contracts from its molten state to atmospheric temperature is true.

Welding thin plate would generally require a lower amperage because thin materials have less mass and therefore require less heat to achieve proper fusion. Using a higher amperage could result in excessive heat and potential damage to the thin plate.

A flux-covered electrode is used in arc welding to provide filler metal. The flux coating on the electrode melts during the welding process, creating a protective gas shield that prevents oxidation and contamination of the weld. The filler metal is also contained within the flux coating, which is released as the electrode melts. This allows for the deposition of additional metal into the weld joint, strengthening and filling any gaps or voids. Therefore, it is true that a flux-covered electrode provides filler metal in the arc welding process.

The joint in question is called a Double V Butt joint. This type of joint is formed by two pieces of material with V-shaped grooves on both sides, which fit together to form a strong and secure connection. The V-shaped grooves increase the surface area for welding or brazing, resulting in a stronger bond. This joint is commonly used in welding applications where a high-strength connection is required.

Amperage refers to the amount of electric current flowing through the welding circuit. Incomplete penetration occurs when the weld does not fully penetrate the joint, resulting in a weak and unreliable weld. When the amperage is too low, there may not be enough heat generated to fully melt the base metal and filler material, leading to incomplete penetration. Therefore, amperage too low is a common cause of incomplete penetration in welding.

The best practice for discarding electrode stubs during welding operations is to drop them into a metal container. This is because electrode stubs can still be hot and may pose a fire hazard if left on the ground or the bench. By dropping them into a metal container, the risk of fire is minimized as the container can safely contain the heat and prevent any potential accidents. Additionally, using a metal container ensures that the stubs are properly disposed of and can be recycled or disposed of in an appropriate manner.

Fillet welds are the name given to the welds that are used to form joints such as a T joint. These welds are commonly used in structural and fabrication applications to create strong and durable connections between two pieces of metal. Fillet welds are characterized by their triangular shape and are typically formed by depositing a filler metal along the edge or corner of the joint. They provide excellent strength and load-bearing capacity, making them suitable for a wide range of welding applications.

The statement is true because when a cup is formed at the electrode tip, it helps to direct the molten droplets of filler metal to the required spot. This occurs because the core wire melts more quickly than the flux coating, creating a cup shape that guides the molten metal. This process is commonly used in welding to ensure accurate and precise placement of the filler metal.

The difference between a 15 amp plug and a 10 amp plug is that the 15 amp plug has a larger earth pin. This means that the 15 amp plug is designed to handle a higher electrical load compared to the 10 amp plug. The larger earth pin provides better grounding and helps prevent electrical shocks and accidents.

The single V butt joint is a common type of weld joint used to join two pieces of metal at a 90-degree angle. It is typically used for materials up to 15mm thick because it provides good penetration and strength for these thicknesses. For thicker materials, a double V butt joint or other joint configurations may be more suitable to ensure adequate penetration and prevent defects.

The ventilation or extraction system in a welding booth should not be switched off as soon as you have finished welding. This system is crucial for removing harmful fumes, gases, and particles generated during the welding process. It is important to keep the system running for a while after welding to ensure that all the contaminants are properly removed from the booth, providing a safe and healthy environment for the welder and others in the area.

The statement is false because the workpiece and welding equipment should be prepared before turning on the main switch. This is because preparing the workpiece and equipment involves ensuring they are clean, properly positioned, and ready for welding. Once they are prepared, the main switch can be turned on to supply power to the welding equipment and initiate the welding process.

Undercut is a welding defect that occurs when the metal at the base of the weld is melted away, leaving a groove or depression. This can be caused by several factors. When the amperage is too high, excessive heat is generated, leading to excessive melting and potential undercut. Similarly, when the arc is too long, it can result in excessive heat input and melt away the base metal. If the electrode is inclined too much towards the face of the work or if it is too large, it can create a wider weld pool, increasing the chances of undercut.

All of the mentioned methods can help in limiting distortion. Pre-setting parts out of position ensures that they are correctly aligned before welding, reducing the chances of distortion during the welding process. Pre-heating areas of metal away from the joint helps in distributing heat more evenly, preventing localized distortion. Tack welding or clamping parts of the job holds them in place, minimizing movement and distortion during welding. Therefore, all of these methods combined can effectively limit distortion in welding.

The purpose of the coating on an arc welding electrode is to provide a protective gaseous shield for the molten weld metal, provide a cleaning action on the workpiece, and create a protective slag cover over the solidifying weld metal. Additionally, the coating helps to stabilize the arc and remove oxygen from the weld metal. Therefore, all of the given options are correct.

In the process of electric welding, an arc is maintained between the parent metal and an electrode. This is because the parent metal serves as the workpiece that needs to be welded, while the electrode is the consumable material that is melted to create the weld. The arc is formed when a high voltage is applied between the parent metal and the electrode, creating a path for the electric current to flow. This current heats the electrode and the parent metal, causing them to melt and fuse together, forming the weld joint.

The statement suggests that varying rates of expansion and contraction in different parts of the job generally do not cause distortion. However, this is incorrect. Varying rates of expansion and contraction can indeed cause distortion in different parts of the job, especially when materials with different coefficients of thermal expansion are involved. This can lead to warping, bending, or other forms of distortion, affecting the overall quality and integrity of the job.

The MMAW process, also known as Manual Metal Arc Welding or Shielded Metal Arc Welding, involves melting the core wire of the electrode and mixing it with the parent metal. This creates a bond between the two materials, resulting in a strong and durable weld. The other statements in the options do not accurately describe the MMAW process.

The statement suggests that it is difficult to maintain the arc and prevent the electrode from sticking when the amperage is too high. However, this statement is false. In reality, it is difficult to maintain the arc and prevent the electrode from sticking when the amperage is too low. When the amperage is too low, the arc becomes unstable and the electrode tends to stick to the workpiece, making it difficult to weld properly.

The size of electrodes used does not depend solely on the type of joint to be welded. It also depends on the thickness of the material being welded. Different thicknesses of material require different sizes of electrodes in order to ensure a proper and effective weld. Therefore, the statement that the size of electrodes used depends only on the type of joint to be welded, irrespective of the thickness of the material, is false.

Good fusion ensures that the weld is fully bonded to the parent metal.

Full penetration ensures that the weld metal reaches and bonds with the entire thickness of the parent metal.

No entrapped slag prevents impurities from weakening the weld.

Slight reinforcement ensures that the weld is slightly raised above the parent metal, indicating proper weld penetration and strength.

Slag inclusions are discontinuities in a welded joint caused by the entrapment of slag during the welding process. They are considered defects and can weaken the welded joint, rather than increasing its strength. Therefore, the statement suggesting that slag inclusions tend to increase the strength of the welded joint is incorrect.

The approximate angle that the electrode should make with the weld surface is 65-70 degrees. This angle is important because it allows for proper penetration and fusion of the weld. A steeper angle may result in insufficient penetration, while a shallower angle may cause excessive heat buildup and potential burn-through. Therefore, a 65-70 degree angle provides a balance between achieving a strong weld and avoiding potential issues.

The correct answer is "In any 5 minute period the total welding time should not exceed 1 minute 15 seconds." This means that if the small welder has a duty cycle of 25% over 5 minutes, it can only be used for a maximum of 1 minute and 15 seconds during that time period. This is because the duty cycle represents the percentage of time that the welder can be used compared to the total time. Therefore, it is important to limit the welding time to ensure that the welder does not overheat and to allow it to cool down properly.

When the amperage is too high in welding, it can lead to several negative effects. Excessive spatter occurs when there is an excessive amount of molten metal expelled during the welding process, resulting in a messy and inefficient weld. Undercut refers to a groove or depression along the edges of the weld, which weakens the joint. A flattened bead is a sign of poor weld formation, where the molten metal spreads out too much and loses its desired shape. Therefore, the correct answer includes these three effects of amperage that is too high.

The lack of fusion can be caused by an electrode that is too small for the job, as it may not provide enough heat to properly melt the base metal. Additionally, if the amperage is too low, there may not be enough heat generated to achieve proper fusion. Wrong electrode angle and wrong speed of travel can also result in lack of fusion, as they can affect the penetration and heat distribution. Finally, scale or dirt on the joint surface can prevent proper fusion by creating a barrier between the base metal and the electrode.