Welder
Definition :- Welding is a permanent metal joining process by which two similare or dissimilar metals may be joined by heating them to a suitable temperature with or without the use of filler metal and with or without the application of external pressure .
The filler metal has its melting point either approximately the same as that of the work piece metal or little lower but normally above the 427c .
Kinds :- There are two kinds of Welding .
Homogeneous Welding :-
It consists of those processes in which similar metals are joined with the help of same filler metal .
example — (i) M.S. to M.S. by- using M.S. electrode / filler rod .
(ii) Brass to Bress by using brass filler rod .
Heterogeneous Welding :
It is a method in which similar or dissimilar metals to be joined on welded by the application of third metal on alloy , which have got low melting temperature than the metal to be welded .
example — (i) M.S. to . M.S. by using bronze filler Rod
(ii) M.S. to C.I. by using brass filler rod .
Classification :
Welding processes may be broadly classified into two categories .
They are — (i) Pressure welding
(ii) Fusion welding .
(i) Pressure Welding :- The welding method in which similar metals are joined together by heating them to plastic or partially molten state and then joined by pressing or hammering without the use of filler metal is called pressure welding .
This is a fusion method of welding with pressure . This joint is made permanent . Heat source may be black mith forge (forge welding) or electric resistance (nesistance welding) or friction .
(ii) Fusion Welding :- A method of welding in which similar on dissimilare metals are joined together by melting and fusing their joining edges with or without the addition of filler metal but without the applitcation of any kind of pressure is called fusion welding .
The joint made in permanent . The common heating sources are :-
— Welding arc (Arc welding)
— Gas flame (Gas welding)
— Chemical reaction (Thermit welding)
Non-Fusion Welding :
This is a method in which similar or dissimilar metaIs are joined together with out melting the edges of the bese metal by using a low melting point filler rod but without the application of pressure .
example : Silver Soldering , Brazing .
