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Different welding parameters and the forces acting on the molten droplet play characteristic roles with specific welding processes. The case of the coated electrodes, MIG Welding Machine-both with solid and flux cored wires and SAW Welding Machine are of special interest due to the important and extensive use of these processes in the welded fabrications.
Metal Transfer in Arc Welding Machine (SMAW)
The drop transfer is a good way of characterising the mode of the metal transfer for any particular process and as it is relatively easy to measure, experimental data are easily available.
The possible explanation for this is that the transfer may be of the explosive type when insufficient amounts of silicon and manganese are added to the electrode coating and this generates small droplets with high rate of metal transfer. On the other hand with fully deoxidised electrode, the droplets are relatively large, of the order of 1 mm diameter, and the metal transfer rate is low at about 10 droplets per second.
Due to low current densities employed is Arc welding machine, the metal transfer takes place mainly by three modes viz, short-circuit, globular, and projected spray. However, for any given current density transfer from coated electrodes is at a higher rate than that for MIG Welding Machine or SAW Welding Machine which is consistent with the fact that the general characteristics of transfer with coated electrode differs from that with bare wire processes.
In welding machine with coated electrodes it has also been observed the weld penetration is equal to the cavity formed in the weld pool due to the arc forces. In this process the current density is too low to produce an electromagnetic jet, and the gas flow takes place mainly as a consequence of the decomposition of the electrode coatings and to a limited extent due to the chemical reactions of the core wire material at the high temperature of the arc. Also, if the electrodes are baked at a temperature high enough to drive off all volatile material, it renders them unusual which points to the fact that in normal operation the metal droplets are carried across the arc in the gas flow generated by the decomposition of the coating. The intensity of the gas stream in Arc Welding Machine (SMAW) increases with coating thickness such that it becomes quite strong with heavily coated electrodes making them to fit for use as cutting electrodes for metals.
In Arc Welding Machine (SMAW) it is possible to make satisfactory welds with 3 mm diameter electrode at 50 to 120 A while in MIG Welding Machine the same sized wire needs 200 to 250A for its successful operation. The only possible explanation for this anomaly is that the gas flow and hence the arc flow is provided in Arc Welding Machine (SMAW) by the decomposition of the coating whereas in MIG Welding Machine , it is dependent on the electro-magnetically included jet which becomes effective only at relatively higher currents.
It is ‘the Arc Welding Process’ known to even a layman and can be considered a ‘roadside welding process’ in india. When invented in 1880’s it used bare electrodes, however the subsequent developments led to the use of coated electrodes. This process is also known as stick electrode welding or coated electrode welding or manual metal arc welding. It uses coated electrodes of 2.5 to 6.35 mm diameter and 300-450 mm length held in an electrode holder. The power source used is of the constant current type and both ac and dc supplies can be employed with equal ease and effectiveness in most of the cases.
In arc welding machine when an arc is struck between an electrode and the work piece, the electrode core wire and its coating melt, the latter provides a gas shield to protect the molten weld pool and the tip of the electrode from the ill effects of the atmospheric gases. The temperature in the core of the arc ranges between 6000-70000C. The radiations originating from the welding arc can damage the eyes thus necessitating the use of a protective shield.
In all types of welding machines, arc welding machine process is very versatile and is used for welding in all positions and all metals for which electrodes have been developed. The coated electrodes are presently available for welding low carbon steels, low alloy steels, quenched and tempered (Q&T) steels, high alloy steels, corrosion resistance steels and stainless steel as well as for cast iron and malleable iron. It is also used for welding nickel and nickel alloys and to a lesser extent for welding copper and copper alloys. It finds a limited use in welding aluminium alloys. Typical applications of the process include its extensive use by the industry for fabrication of ships, bridges, pressure vessels and structurals. However, as the process can be used in its manual mode only. It is slowly getting replaced by other welding processes for heavy fabrication where large quantity of metal need be deposited.
We are well recognized to manufacturing welding machines, especially manufacturer and exporter of Arc Welding Machines. Our range starts from 150 Ampere to 650 Ampere in different designs equipped with latest technology.
Our products are efficient in all welding positions like flat position, horizontal position, vertical position and overhead position. Model CW-ARC150,CW-ARC200,CW-ARC250,CW-ARC320 are portable type arc welding machines, these arc welding machines are easy to carry, light weight and specially designed for movable job purposes.
Basic advantage of portablewelding machine is use in two phase as well as in single phase connection. So it can be in small scale industries, home base industries, where three phase connection is rarely available. We recommend our arc welding machine for offshore sites and onshore sites both.