Techniques in joining and assembly processes
Mechanical joining
•Welding
•Soft soldering
•Hard soldering and brazing
•Adhesive bonding
•Riveting
•Screwed fastening
Electrical and electronic joining
•Soft soldering
•Hard soldering and brazing
•Crimping
Fusion welding
•The required joint is obtained by heating the two metal pieces to liquid state locally, at the place of joint.
•The two metals will melt and form a common pool of liquid metal.
•Sebsequent cooling will form the solid
Pressure welding
•The two metal pieces are heated to some temperature below their melting temperatures and the required joint is obtained by applying sufficient pressure between the two pieces
OXY-ACETYLENE GAS WELDING
–Process of joining two metals by melting the adjoining surfaces.
–Source of heat generated in gas welding is by the combustion of a mixture of oxygen and a fuel gas.
–Move molten pool back & forth between the metal.
Chemicals Used
•Oxygen
–Colorless, odorless, tasteless gas
–Supports combustions & increase heat
–Produce by cooling air to a low temperature and turning it into liquid where the oxygen separates out.
•Acetylene
–Colorless, has a very distinctive odor
–Highly flammable
–Produce by mixing calcium carbide (coke + limestone burnt together) and water yields acetylene and calcium hydroxide.
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