Page 82 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

1 67

Figure 1.94 MIG welding process

brass and steel can also be joined and less heat is required than when fusion
welding. Brazing is only used on a few areas of the vehicle body.

1.6.12 Welding

Welding is a method of joining metals by applying heat, combined with pressure
in some cases. A fi ller rod of a similar metal is often used. The welding process
joins metals by melting them, fusing the melted areas and then solidifying the
joined area to form a very strong bond. Welding technology is widely used in the

automotive industry.
The principal processes used today are gas and arc welding, in which the heat
from a gas fl ame or an electric arc melts the faces to be joined. Figure 1.94
shows a welding process in action.
Several welding processes are used:
Gas welding uses a mixture of acetylene and oxygen which burns at a very
●
high temperature. This is used to melt the host metal with the addition of a
fi ller rod if required (OA or oxyacetylene).
Shielded metal-arc welding uses an electric arc between an electrode and the
●
work to be joined; the electrode has a coating that decomposes to protect the
weld area from contamination and the rod melts to form fi ller metal (MMA or
manual metal arc).
Gas-shielded arc welding produces a welded joint under a protective gas (MIG
●
or metal inert gas).
Arc welding produces a welded joint within an active gas (MAG or metal active
●
gas).
Resistance welding is a method in which the weld is formed by a combination
●
of pressure and resistance heating from an electric current (spot welding).
Other, specialized types of welding include laser-beam welding, which makes
use of the intensive heat produced by a light beam to melt and join the metals,