Construction Of Welding Machine

CHAPTER TWO
2.0    ANALYSIS OF ALTERNATE METHOD OF WELDING AND CHOICE OF BEST METHOD
2.1    ALTERNATIVES TO ELECTRIC ARC WELDING MACHINE
2.1.1    JOINING PROCESS
Semi conductor packaging is complex process of forming many different parts and piece together. To achieve this, semi conductor packaging employs a multitude of joining process.
The ability to choose is appropriate as every step of packaging is critical in producing highly reliable packaging for semi conductor device. Listed below are brief descriptions of common joining process used not only in semi conductor assembly but in other industry as well. These are;
    Gas welding
    Soldering
    Brazing
2.1.2    GAS WELDING
Gas welding is the process of joining metal in which the end of pieces to be joined are heated at their interface by producing coalescence with one or more gas flame (such as oxygen and acetylene), without the use of a filler metal. Gas welding is also known as OXY-ACETYLENE. Gas welding involves using a gas-fed touch to heat the metal part to be welded.
The three common flames used in gas welding are;
i.    Neutral flame
ii.    Oxidizing flame
iii.    Carburizing flame
Each form of these flames can b obtained through the regular action of the flow of both oxygen and acetylene gases. The bluish part is the hottest. Materials to be welded determine the type of flame to be used.
i.    NEUTRAL FLAME
The neutral welding flame has one-to-one ratio of acetylene and oxygen. It obtains additional oxygen from the air and provides complete combustion. It generally preferred for welding. The neutral flame has a clear, well defined or luminous cone indicating that combustion is complete.
The neutral flame is the primary flame used by gas welding. A neutral flame has two zones a hotter lighter inner zone and a cooler darker outer zone. The welder use the tip of the inner flame zone to heat the part s to be welded as this is the hottest part of the flame. Neutral welding flames are commonly used to weld; mild steel, stainless steel, cast iron, copper, aluminum.