What is Induction Hardening In Heat Treatment of Metals ?

Induction Heating has proved satisfactory for many surface hardening operations as required on the bearing areas of the crankshafts , camshafts, axle shafts, and similar wearing surfaces. It differs from ordinary case - hardening practice in that the analysis of the surface steel is not changed, the hardening being accomplished by an extremely rapid heating and quenching of the wearing surface which has no effect on the interior core. The hardness obtained in induction hardening is the same as that obtained in conventional treatment and depends on the carbon content.

In this process, a high - frequency current of about 2000Hz is passed through a copper inductor block which acts as a primary coil of a transformer. The block is placed around but does not touch the surfaces to be hardened. The heating effect is due to the induced eddy current and hysteresis loss in the surface material. The hardening temperature is about 750*C to 760*C for 0.5 % carbon steel and 790*C to 800*C for alloy steel. The heated areas are then quenched immediately by sprays of water delivered through numerous small holes in the block. Both automatic and hand control can be employed. A depth of case of approximately 3mm is obtained in about 5 seconds.

Although the equipment cost is high, it is practiced by the advantages of the process used, which include fast operation, freedom from scaling, clean operation, little tendency for distortion, no manual handling of the hot parts, and low treating cost. Medium carbon steel has proved satisfactory for parts, and the nature of the process has practically eliminated the necessarily for using costly alloy steels.

Comments

ELECTRICAL COMPARATORS AND ITS WORKING

Electrical Comparators are used as a means of detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a roll. The objec...

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...

TOP POLLUTION RECORDED IN WORLD

CHERNOBYL NUCLEAR DISASTER (NUCLEAR POLLUTION) : In April 26,1986, the melt down of the Chernobyl nuclear reactor , in Russia, has leaked out the radioactive rays and radioactive materials. Effects : 1. In this Pollution nearly 2000 persons have been killed by the accident. 2. People suffered due to the illness such as, degeneration of the cells, severe bleeding, anemia, skin cancer. 3. Animals, Plants are also affected by nuclear radiation. MINAMATA EPIDEMIC (1953) : MARINE POLLUTION ( CASE STUDY ) Minamata is a small coastal village in Japan. The Chisso Chemical Company , which produces vinyl polymer plastics used organomercurial compound. The industry released its effluent into Minamata sea. The effluent containing mercury ions is converted into methyl mercury, which is highly toxic. The marine organisms like phytoplankton and zoo-planktons easily absorb the toxic methyl mercury compound. These organisms are consumed by small fishes and these are in ...

Mechinopedia For Mechanical Engineers

Search This Blog