5.Advanced Welding process
and inspection methods
Non fusion type: resistance welding
Fusion welding: The metal at the joint is heated to molten state and it is allowed is
allowed to solidify
non fusion welding: The metal parts are heated to a plastic state and they are
pressed together to make joint.
Resistance welding:
in resistance welding the work piece is heated with an application of the current
and the heat is produced by the resistance of the current.
The most important advantage is that it does not use any filler material.
the welding is done within 2 to 8 volts ( low voltage and a high current )
the special thing abt resistance welding is that the welding happens in fraction of
a second ( current is passed only for small time typically 0.25s )
when the work piece is heated up the current supply is stopped and mechanical
pressure is applied immediately, completing the welding.
The heat generated in resistance welding : H = k (I^2) Rt
i = current in A
t = time in seconds
R = resistance in ohms
k = a constant to account for the heat losses from the welded joint
5.Advanced Welding process and inspection methods 1
, electrode are usually made of copper or any material that is a good conductor of
heat and electricity
Resistance spot welding
most common resistance welding process
essentially done for joining two sheets in lap joint forming a small nugget at
interface of the two plates
machine consists of two rods out of which one is fixed
the other electrode is fixed to a rocker arm for transmitting pressure from a
pneumatic cylinder
this is the simplest possible arrangement
there is a portable machine available for welding big work pieces
5.Advanced Welding process and inspection methods 2
and inspection methods
Non fusion type: resistance welding
Fusion welding: The metal at the joint is heated to molten state and it is allowed is
allowed to solidify
non fusion welding: The metal parts are heated to a plastic state and they are
pressed together to make joint.
Resistance welding:
in resistance welding the work piece is heated with an application of the current
and the heat is produced by the resistance of the current.
The most important advantage is that it does not use any filler material.
the welding is done within 2 to 8 volts ( low voltage and a high current )
the special thing abt resistance welding is that the welding happens in fraction of
a second ( current is passed only for small time typically 0.25s )
when the work piece is heated up the current supply is stopped and mechanical
pressure is applied immediately, completing the welding.
The heat generated in resistance welding : H = k (I^2) Rt
i = current in A
t = time in seconds
R = resistance in ohms
k = a constant to account for the heat losses from the welded joint
5.Advanced Welding process and inspection methods 1
, electrode are usually made of copper or any material that is a good conductor of
heat and electricity
Resistance spot welding
most common resistance welding process
essentially done for joining two sheets in lap joint forming a small nugget at
interface of the two plates
machine consists of two rods out of which one is fixed
the other electrode is fixed to a rocker arm for transmitting pressure from a
pneumatic cylinder
this is the simplest possible arrangement
there is a portable machine available for welding big work pieces
5.Advanced Welding process and inspection methods 2
