RESISTANCE WELDING

                         RESISTANCE WELDING

the welding process covered so far, are fusion welding  process where both only heats is applied in the joint in contrast resistance welding process  is a fusion welding process where  both heat and pressure are applied to the joint but on the joint out on filler metal or flux is added,

principal

in the resistance welding(R. W)  a low voltage nd very high current  1500A is passed through the joint for a very short time this amperage near the joint due to the contact resistance at the joint and metals it. the metal fuses together under the pressure. the heat generated in resistance can be expressed as.

h=ki/2 rt

where
h=the total heat generated
i= electric current
t=time

Advantage

1.very little skill required to operate the resistance welding machine.

2.these are very small suited for mass production 

3. heating of the workpiece is contained to a very small part which result in less distrution.

4. it is possinle to used to weld dissimilar meatals as well as meatls platee of different thickness.

disadvantages

1. the resistance  welding machine is highly complex with various elements  such as heavy conductors  for carrying the high current. it is tough to handle in tranport.

2. the resistance welding macjine highly expensive unless it is used for large scale purpose.

3. certain resistance  welding process is limited only to tap joint. it usee to sheet metal  whose thickneee is less then3mm.
the lap joint have an extra ordinary  case  if have large thickness nuget will also should be thick