Induction Welding process And Application

INDUCTION WELDING

That welding process in which weld is produced by the the heat obtained from the resistance of the weldment to flow of an an induced electrical current is known as induction welding.

process : In opreation a high current is induced with both edges of the work close to where weld is to be made .Heating to welding temperature is extremely rapid and the joint is completed by pressure rolls or contacts.A form  of induction welding known as high-frequency welding is similar except that the current is supplied to the conductor being welded by direct contact.High -frequency current flow near the surface of the metal and as heating is almost instantaneous,there as chance of hamful oxides high frequency welding.

Application ; It is a high -speed process and is best suited for high production use. Welding speed ranges from 60 m/mt to 300 m/mt. It is now,being used for most metals ,e.g,copper and copper alloys,nickel ,zirconium and many types of steels.

CORE PRINT

The projections placed on pattern to form seats in the mould for introducing dry sand cores in the mould ,are known as core -prints.

Core Print

core -prints make impressions in the form seats into which the cores may be set and thus reattained in proper position in the mould .when the reversal of a core in the mould would spoil the casting ,the prints are made of such a size and shape that would be impossible to set the core in any position except the proper one.
Core prints should be made to give the least inconvenience in moulding .the print of the core should exactly fit the core seat.the print should be of sufficient and will size and so that impression in the sand will have plenty of bearing surface and will not be crushed out of shape by the weight of the core or by the molten metal.

Ultrasonic welding process and application

The process of joining metal pieces by the localized application of very high frequency .i.e. ultrasonic frequency ,to the metal pieces held together under pressure is known as ultrasonic welding.

process;  ultrasonic welding combines pressure and high frequency motion to form a solid- state bond .a transducer which changes the high frequency electrical power into vibratory energy.The ultrasonic used is coupled to a force sensitive system that contains a welding tip on one end. Either stationary tips,for spot welds, or rotating discs for seam weld can be used.

Application : this processs can be used only for the materials upto about 3 mm in thickness ,alought equipment is being developed to extend this range .there is no minimum limit to the sheet thickness that can be welded .ultrasonic welding is excellent for joining thin sheets to ultrasonic welding is particularly adaptable for joining electrical and electronic components ,also in aircraft and missiles .

Pattern differs from a finished casting

 

MOULDING PATTERN

A model of anything  so constructed that it may be used for forming a mould or impression in damp sand or other suitable material is known as a pattern .The mould produced with the help of a pattern ,when filled with molten metal or substances that solidify ,forms a reproduction of the pattern and is known as a casting .pattern differs in a number of respects from the resulting casting these differences known a pattern allowances ,compensate for metal shrinkage ,provide sufficient metal for machined surface ,and facilitate moulding .A through understanding of these allowances is necessary for successful pattern design and construction .

Cantrolling welding defects

These are the welds with voids ,blow holes or pockets which weaken welds appreciably and gas acts as stress risers from which cracks spread.porosity in welding is a result of dissolved gases or gases released during the welding process ,being trapped in the metal .when there is insufficient time to espace pror to solidification