ADDITION/FABRICATION PROCESSES Flashcards
Explain MIG welding?
An electrical arc is used to create heat which melts the joint area. A wire electrode, that is made from the same metal as the material being joined, is stored on a reel and advances through the welding gun and melts into the join and fills the gap between the pieces being joined. The operator swirls the welding gun as they move over the joint, to form a continuous bead of weld. During the process an inert gas is used to form a flux shield over the area being joined, the gas replaces the oxygen in the air to prevent oxidation occurring that would prevent the weld forming properly.
Explain TIG welding?
It is similar to MIG welding, except the tungsten electrode doesn’t melt into the process and instead a separate filler rod is used.
Explain oxy-acetylene welding?
-The metal is prepared by grinding an angle on the edges of the two pieces to be joined to form a V shape, to ensure that the weld runs through the entire thickness of the metal.
-The joint area is heated to form a melt pool and at the same time a steel filler rod is introduced to the joint area. The melt pool is extended to form a continuous bead along the length of the joint. The molten metal will flow to the hottest part, so by moving the torch along the joint line a continuous seam will be formed.
Explain soldering?
-The metal is cleaned and degreased.
-The joint area should be clamped in place.
-The metal is heated up to the melting point of the solder.
-The solder should be then added to the joint.
-The heat should be removed to allow the solder to cool and set.
-The metal is then cleaned to remove any flux residue.
Explain brazing?
-The material being joined is cleaned and decreased.
-The two pieces are clamped together.
-A flux is applied to prevent the joint from oxidising.
-The joint is heated using an air torch to a temperature of around 850°C.
-The brazing rod is applied to the joint area. The brazing spelter will flow along the joint by capillary action to the hottest part, so it can be made yo follow the joint by manipulating the torch.
Explain riveting?
-It is a permanent joining method used to join sheet metal.
-Two sheets are overlapped and drilled. The rivet is domed on one side and is inserted into the hole. The other end is then hammered over to squeeze the two sheets together.
Explain pop riveting?
-The rivet head is pushed through a drilled hole through the two pieces of metal being joined.
-Riveting pliers grip and pull the pin, and as this happens, the head of the rivet squashes and pulls the two pieces together.
-The pin then breaks off and is disposed of.
