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    Joining metal


    Summary: Learn how to join metal, how to solder metals, how to weld metal together and how to rivet pieces of metal together.


    There are various ways of joining metal, depending on the function and quality of the product, and the strength required.


    Soldering and brazing

    Soldering is a technique used in plumbing and electronic industries to join metals by melting a filler metal (solder) into the joint. Brazing is also a type of soldering using a filler metal with a higher melting point.

    • Consult the materials section for advice on choosing the right type of solder and flux for the job.
    • When soldering, always wear safety goggles. You should also ensure adequate ventilation as the fumes are toxic or wear a respiratory mask.

    Soldering pipes

    • Rub wire wool over the ends of pipe.
    • Paint flux paste onto the ends of pipe and inside a joint insert.
    • Push the ends into the joint insert.
    • Use a blowtorch to heat the outside of the joint. This will melt the solder-ring inside.
    • Stop when solder starts to seep through the joint.
    • If you are using solder wire, heat the pipes and touch the tip of the solder to the joint of the pipe and its fitting to melt it into the joint.
    • After the solder has cooled, wipe away any excess, making sure that solder completely encircles the joint.

    Soldering wires

    If you are working on electronics and computer equipment, soldering wires will form a better electrical connection than using wire nuts and electrical tape.

    • Heat up the soldering iron.
    • Dip the ends of the wire into the flux.
    • Wrap the wires around the appropriate tabs on your circuit board.
    • Touch the flat surface on the tip of the soldering iron to the tabs.
    • Hold the rosin solder against the tab and wires (not touching the iron) and the heat from the tab and wires should melt a bead of solder over the connection.
    • Avoid any movement until the solder has cooled.

    Welding

    Welding is different from soldering in that the base metals being joined are themselves melted, fusing together as they cool. In oxy-acetylene welding a very hot flame is used. In electric arc welding a spark heats the metal.


    Riveting

    Rivets are fixings with cylindrical shafts and a head on one end inserted into pre-drilled (sometimes countersunk) holes to join metals. The end of the rivet is beaten into a dome to keep it in place and the joint is finished using a rivet set or snap.


    Pop riveting

    This technique is used to join thin sheets of metal, such as aluminium, when you only have access to one side of the joint. Pop rivets (otherwise known as blind rivets) come in different lengths and diameters, so choose the right type for the combined thickness of the metals you are joining.

    • Temporarily clamp the two pieces of metal to be joined.
    • Drill holes slightly larger then the diameter of the rivet through the metal sheets.
    • Pass the rivet through holes in both sheets.
    • Choose the insert that corresponds to the diameter of the rivet you're using, and insert it into the pop rivet pliers, or ‘gun’.
    • Push the gun onto the head of the rivet and squeeze the handles together. This will pull the pin through the rivet, expanding the end of the pin. After a couple of squeezes on the handle the rivet will be fully expanded and will break off, leaving the rivet in place holding the sheets together.
    • Remove the broken off shaft from the gun to fix another rivet.
    • Once the rivet is in place, the only way to remove it is to drill out the core of the rivet or grind off the head to pull it out.



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