Welding Practice - The Hong Kong Polytechnic University

Welding Practice
Welding Practice
Objectives:
To understand the basic principles of common welding technologies
To be able to select and apply among different kinds of weld.
1. Introduction
Welding is a permanent joining of two materials, mainly metals, through
localized coalescence, resulting from a suitable combination of temperature,
pressure, and metallurgical conditions. In the last fifty years, welding technology
has been developed extensively and it is now the case that its use may often
result in the saving of time and money when compared with some other
methods of manufacturing. Today, welding is used in a wide range of
applications, both in jobbing production (one off) as well as in the mass
production industries. Typical applications are found in shipbuilding, the aircraft
industry, civil engineering and construction, automobile manufacturing, and
many consumer product manufacturing industries. With the advancement of
automatic welding techniques and equipment, welding is no longer a skill-ofhand-dependent
activity nor is it necessarily a costly process. Nowadays, welding
equipment is often highly automated, including the increasing use of industrial
robots leading to good system flexibility as to use coupled to a high degree of
accuracy and quality. Developments of this kind allow welding now to be used
for work with high precision requirements previously considered impossible and
uneconomical.
1.1 FUNDAMENTAL PRINCIPLES OF WELDING
A weld is defined as a localized coalescence of metals wherein coalescence is
produced by heating the metal to suitable temperatures, with or without the
application of pressure and with or without the use of any filler metal.
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