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What are the effects of the electrode polarity on welding in the SAW process?
Think of Polarity as water flow in a pipe. Reverse Polarity means the flow is from the work to the machine. Straight Polarity is flow from the machine to the work. Heat is released when the flow tries to jump the gap. So in Reverse Polarity (where most SMAW is done) the heat builds up in the base metal which is usually thicker than the Electrode. The extra heat there helps melt the base metal. Straight polarity is usually employed when welding thin metals.
When current flows through a resistance is heat produced?
Yes, heat energy is produced by the electrons;however small it may be,actually if we consider a resistance then it is an hindered to the flow of electrons,as a result of which the electrons collide with the particles of wire resulting in loss of energy in the form of heat.the equation of heat generated is: H=(I^2 *R*t) where- H=heat produced in joules R=resistance of the material in ohm t=time of current flow in seconds
When to use dc welding machine and ac welding machine?
Dc welding can be used for non consumable electrodes with consumable electrode heat is transferred from electrode to work by molten metal. Ac welding is desirable for aluminum and magnesium, because it helps break up oxides AC is more stable than Dc.
Describe the hazards associated with migmag or flux cored wire ard welding such as live electrical components.?
Migmag or flux-cored wire arc welding poses several hazards, including exposure to live electrical components, which can lead to electric shocks if proper precautions are not taken. The intense heat generated can cause burns or ignite flammable materials in the vicinity. Additionally, the welding process produces harmful fumes and ultraviolet radiation, which can pose respiratory and skin risks. Adequate personal protective equipment (PPE) and safety measures are essential to mitigate these hazards.
Why do we need a transformer if we use a welding machine?
A transformer is needed in a welding machine to adjust the voltage and current to suitable levels for the welding process. Here’s why: 1. Voltage Reduction: Welding requires a lower voltage than is typically supplied by the mains power. A transformer steps down the high voltage from the power source to a lower voltage that is suitable for welding operations. 2. Current Adjustment: Welding processes often require high current to generate the heat needed for melting and joining materials. A transformer can adjust the current to the necessary level, ensuring proper welding conditions. 3. Safety: By reducing the voltage to safer levels, transformers help prevent electric shocks and ensure safe operation during welding. 4. Controlled Heat Generation: Transformers help control the heat output by adjusting both voltage and current, which is crucial for achieving high-quality welds with proper penetration and bonding. Overall, the transformer ensures that the welding machine operates effectively and safely by providing the correct voltage and current for the welding process.
What generates the heat for fusion in resistance welding?
In resistance welding, the heat for fusion is generated by passing a high electrical current through the materials being welded. The resistance of the materials to the flow of electrical current causes them to heat up rapidly at the interface, melting and fusing together.
In ultrasonic welding what creates the heat required for welding?
In ultrasonic welding, the heat required for welding is generated by the conversion of mechanical vibrations into frictional heat at the interface of the materials being welded. This frictional heat softens the materials and allows them to fuse together, forming a strong bond upon cooling.
What is the difference between arc welding and resistance welding?
Arc welding uses an electric arc to melt and join metal pieces together, while resistance welding uses heat generated by the resistance to electric current flow between two metal pieces to join them together. Arc welding is more versatile and can be used for various types of metals, while resistance welding is more suited for high-speed production and is commonly used in automotive and appliance manufacturing.
What are welding sparks called?
The sparks generated during welding are called welding sparks. They are tiny fragments of molten metal that separate from the welding material or workpiece due to the intense heat generated during the welding process.
How welding current is generated?
Welding current is typically generated through a power source that converts electrical energy into a suitable form for welding. This can be done through mechanisms like transformers, rectifiers, or inverters, depending on the type of welding process being used. The current is then delivered to the welding arc, where it generates the heat necessary to melt and join the workpieces.
What happens if you light a welding rod with a match?
If you light a welding rod with a match, it will start to burn and produce sparks due to the high heat generated. However, a match may not provide enough sustained heat to fully ignite the welding rod for welding purposes. It is safer and more effective to use appropriate equipment and procedures for welding.
The joining of metals by heat for making something structural or producing a continuous and permanent path for the flow of electric current is known as?
welding
What are the effects of the electrode polarity on welding in the SAW process?
Think of Polarity as water flow in a pipe. Reverse Polarity means the flow is from the work to the machine. Straight Polarity is flow from the machine to the work. Heat is released when the flow tries to jump the gap. So in Reverse Polarity (where most SMAW is done) the heat builds up in the base metal which is usually thicker than the Electrode. The extra heat there helps melt the base metal. Straight polarity is usually employed when welding thin metals.
What is phosgene in welding?
Phosgene is a toxic gas that can be produced during welding when chlorinated hydrocarbon solvents come into contact with UV radiation or heat generated by the welding process. Exposure to phosgene can cause serious respiratory issues and even death. Proper ventilation, personal protective equipment, and avoidance of chlorinated solvents are key to preventing phosgene exposure during welding.
What is the Different between TIG arc welding and gas welding?
Gas welding basically used for weaker joints(in sheets) and arc welding for stronger one(plates). mobile welding (not in a shop)is the ideal time for arc welding . gas welding is the way to go as far as production is concerned , but requires environment with little air circulation or wind , plus gas bottle , machine , and a short lead , which makes it ideal for shop work answer Gas welding - generally use for welding of thin plates/pipes. Less heat input and less likely to burn off the edge of the plates (undercut). It is a more expensive process because of gas shielding. Arc welding - use for thicker plates usually with larger size electrodes. Higher weld production rate. Shielding by means of electrode coating. Both processes can meet the required mechanical properties usually
What are three sources of heat that may cause fire?
Three common sources of heat that may cause a fire include electrical malfunctions, open flames (such as candles or gas stoves), and sparks generated by grinding or welding tools.
What is the term tw refers to in welding?
TW = thermite welding, a welding process that requires no external source of heat or current.
