Skip to main content

NEWER TYPES OF WELDING METHOD - Electron - Beam Welding

 These types are called "newer" since these are not in use for many many years and have been developed very recently. The types are :

1.) Electron - Beam Welding 

2.) Laser - Beam Welding. 

Electron - Beam Welding And Its Process :

Electron beam welding utilizes the energy from fast moving beam of electrons focused on the work piece. The electrons strike the metal surface , which gives up kinetic energy almost completely into heat. The beam is created in a high vacuum (10^-3 to 10 ^-5 mm Hg). If the work is done is such vacuum, no electrodes, gases, or filler metals can contaminate it, and pure welds can be made. Moreover, High vacuum is necessary around the filament so that it will not burn up and will also produce and focus a stable beam. 

In all types of electron beam machines, a tungsten filament which serves as a cathode emits a mass of electron that are accelerated and focused to a 0.25 - 1mm diameter beam of high energy density up to 0.5 to 10 kW / mm2. The heat generated is about 2500*C. This is sufficient to melt and vaporize the workpiece material and thus fills a narrow weld gap even without a filler rod (although filler rods may be used).

The speed of the beam is stepped up to one-half to two-thirds of the speed of the light by passing it through a high-voltage electrostatic field. An electromagnetic lens is employed to obtain correct focusing of the beam.

Near Zero Pressure is necessary for the formation of the beam. The chamber is evacuated to a pressure to 10 mm Hg. Welding begins at this point. A similar processes, known as non vacuum electron beam welding is rapidly coming into use today. This means that many welds can now be made without elaborate arrangement required for vacuum electron beam welding. In that case, the vacuum chamber in which the beam is created is evacuated to a lower pressure. In situation where contamination of the workpiece must be held to minimum , the beam should be passed through argon or helium. To make the chamber high vacuum , it takes about 5 to 30 min to evacuate the air, depending on the size of the chamber. A medium size electron beam welder operates below 60 kV. The welding head or the work is moved by the numerical control or by hand. 

Today automobile, airplane, aerospace, farm and other types of  equipment including ball-bearing over 100 mm are being welded by the electron beam process.

The advantages of  EBW are that the welds are clean, with no porosity since there is no air ; so shielding gas is needed ; and as the energy input is in a narrow , concentrated beam, distortion is almost eliminated. The speed may be as fast as 2500 mm/min, and it will weld or cut any metal or ceramic , diamond, sometimes as thick as 150 mm. 


Electron Beam Welding


Labels:

Comments

Post a Comment

Popular posts from this blog

Advantages And Disadvantages Of Air Refrigeration System :

 Advantages Of  Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of  Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content. 
Post a Comment
Read more

SIMPLE CARBURETOR - CONSTRUCTION AND WORKING

CONSTRUCTION OF SIMPLE CARBURETOR :  The main Components of Simple Carburetor are : Float Chamber, float, nozzle, venturi, throttle valve, inlet valve, and metering jet . In the float chamber, a constant level of petrol is maintained by the float and a needle valve.  The float chamber is ventilated to atmosphere.  This is used to maintain atmospheric pressure inside the chamber. The float which is normally a metallic hollow cylinder rises and closes the inlet valve as the fuel level in the float chamber increases to certain level. The mixing chamber contains venturi, nozzle and throttle valve. The venturi tube is fitted with the inlet  manifold. This tube has a narrow opening called venturi. A nozzle is provided just below the centre of this venturi. The nozzle keeps the same level of petrol as that of the level in the float chamber. The mixing chamber has two butterfly valves.  One is to allow air into the mixing chamber known as choke valve. The other is to al...
Post a Comment
Read more

MELTING FURNACES FOR FERROUS METALS : CUPOLA AND ITS WORKING

Various types of melting furnaces are used in different foundry shops, depending upon the quantity of metal to be melted at a time, and the nature of work that is carried out in the shop.  The primary objective in cupola is to produce iron of desired composition, temperature and properties at the required rate in the most economical manner. Besides, this furnace has many distinct advantages over the other types, e.g., simplicity of operation, continuity of production, and increased output coupled with a high degree of efficiency.  Description Of a Cupola : The Cupola Furnace consists of a vertical, cylindrical steel sheet, 6 to 12 mm thick, and lined inside with acid refractory bricks or acid tamping clay. The refractory bricks or the tamping clay used consist of  silicon oxide acid (SiO2) and alumina (Al2O3). The lining is generally thicker in the lower where the temperatures encountered are higher than in the upper region. The shell is mounted either on a brick work fo...
Post a Comment
Read more