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Magnetic arc blow, also known as arc wander is the arc deflection caused by distortion of the magnetic field produced by an electric arc current. When welding ferromagnetic steels, lack of fusion imperfections can be caused through uncontrolled deflection of the arc, usually termed arc blow.
What do you mean by arc blow?
Arc blow is the, usually unwanted, deflection of the arc during arc welding. There are two types of arc blow commonly known in the electric welding industry: magnetic and thermal.
What is arc blow and when does it occur?
Arc blow occurs in DC arc welding when the arc stream does not follow the shortest path between the electrode and the workpiece and is deflected forward or backward from the direction of travel or, less frequently, to one side. First, let’s examine some of the terms associated with arc blow.
What is arc blow and how is it controlled?
Arc blow can be controlled or reduced by connecting the work lead to the end of the weld joint, and then welding away from the work lead. Another way of controlling the arc blow is to use two work leads, one on each side of the weld. The best way to eliminate the arc blow is to use alternating current (AC).
How do I stop arc blow?
If you’re struggling with this issue there are five things to try: Switch to AC power. Welders generally prefer DC because it makes for easier starting and there’s usually less arc wander. Shorten the arc length. Wrap the ground cable around the workpiece. Angle the torch. Tack Welds.
Why does arc blow occur?
Such arc deflection, usually forward or backward of the welding direction, is known as ‘arc blow’. Arc blow tends to occur if the material being welded has residual magnetism at a certain level, particularly when the weld root is being made, and the welding current is direct current (DC positive or negative).
Which welding is free from arc blow?
In AC welding, since the current and the magnetic field of the arc reverse direction many times a second, there is no net deflection of the arc.
Where does arc blow normally occur?
With experiments, magnetic arc blow issues frequently occur when welding with DC current in deep groove joints (mainly V joints) and at the corners of the workpiece using a high current.
What is arc length in welding?
The distance from the tip of the welding electrode to the adjacent surface of the weld pool.
What is the duty cycle of a welder?
Duty cycle is the percentage of time that a machine will safely operate (or weld), within a certain time period, at a given amperage. This means that it will operate at 200A for 3 minutes within a 10 minute time period. For the remaining 7 minutes, the machine will switch to thermal overload to cool down.
How does arc blow affect welding?
Arc blow can cause a number of welding problems, including excessive spatter, incomplete fusion, porosity and lower quality. Forward blow is encountered when welding away from the workpiece connection, or at the starting end of the joint.
What are the three types of metal transfer?
3 Process Variations-Metal Transfer The basic mig process includes three distinctive process techniques: short circuiting metal transfer, globular transfer, and spray arc.
Why electrode is coated with flux?
Flux coating on the electrodes ensures a weld with good mechanical properties, chemical composition and weld metal cleanliness.
Are arc welders safe?
Properly installed and used the arc welder is very safe, but if used improperly the operator can be exposed to a number of hazards including toxic fumes, dusts, burns, fires, explosions, electric shock, radiation, noise, and heat stress. Any of these hazards can cause injury or death.
What is arc voltage in welding?
Gases. 2 VOLTAGE Arc voltage is the voltage between the end of the wire and the workpiece. Because of voltage drops encountered in the welding system, the arc voltage cannot be directly read on the power source voltmeter.
Is MIG welding arc welding?
Metal Inert Gas (MIG) welding is an arc welding process that uses a continuous solid wire electrode heated and fed into the weld pool from a welding gun. The two base materials are melted together forming a join.
What electrodes are used in arc welding?
The carbon electrode is a non-filler metal electrode used in arc welding or cutting, consisting of a carbon graphite rod that may or may not be coated with copper or other coatings. The tungsten electrode is defined as a non-filler metal electrode used in arc welding or cutting, made principally of tungsten.
What is the basic principle of arc welding?
Arc welding is welding using the heat of an arc as a heat source. In arc welding, positive voltage is applied to the electrode (welding rod/wire) and negative voltage is applied to the base material. This makes an arc occur from the base material to the electrode.
What is the ideal arc length?
As a good starting point, arc length should not exceed the diameter of the metal portion (core) of the electrode. For example, an 1/8-inch 6010 electrode is held about 1/8 inch off the base material. Too long of an arc length will create excess spatter in the weld joint. There is also a high potential for undercut.
What is a 100% duty cycle?
A 100% duty cycle simply means the compressor will deliver a consistent CFM and PSI the entire time the compressor is in use, which is different than being able to run continuously.
What is 60 duty cycle in welding?
What does a 60% duty cycle mean? A 60% duty cycle means that within any period of time, you can safely run your welding machine for up to 60% of that time period at a certain amperage. Usually, during testing, this percentage is calculated by running a machine for 5 to 10 minutes.
Which of welding rod is the largest?
3/4″ x 39″ Worlds Largest Stick Welding Electrode.
What is arc initiation?
For thick electrodes, the arc initiation is done by touching the electrode to the workpiece and then withdrawing it. This method of initiating the welding arc is known as ‘touch’ method and the arc so initiated is called a ‘drawn’ arc. This method is used for arc initiation in manual metal arc welding or SMAW process.
