Technology and our changing world high Technology

TINNING A SOLDERING COPPER
A soldering copper must be tinned (coated with solder) if it is to do its job properly. This is done by filing the point clean, and then heating the copper. Rub the point of the heated copper on a cake of sal ammoniac. Then apply a few drops of solder until the tip is coated. The copper is now ready for use.


SOLDERING A JOINT

1. 
   Place the pieces to be soldered over a bendi th at has a heat-resistant top.
   
2. 
   Heat the soldering copper. A copper is hot enough if it makes a “flying” sound when rubbed on the sal ammoniac block. Never allow a copper to become red hot.
   
3. 
   App ly th e correct flux.
   
4. 
   Press the copper to one end of the seam until its heat melts the solder it touches. This is called tacking. Don’t let the solder melt on the soldering copper.
   
5. 
   Tack the seam at both aids. Then start at one end and hold the copper flat against the seam until the soldo- starts to flow freely. Apply a little solder beneath lhe copper and push or draw the copper slowty along the seam. Make sure that the soldo- melts and spreads correctly. Sometimes a tool or other piece of metal can be used to hold the pieces together while the solder is hot.
   

Brazing
Brazing is a form of soldering that uses a gas torch to produce heat. The metals to be joined are not melted in brazing. Instead, another piece of metal, called a brazing rod, is melted onto the edges of the pieces to be joined. When this molten metal hardens, the jo intis formed.


BRAZING EQUIPMENT AND MATERIALS
Brazing equipment consists of a cylinder of oxygen, a cylinder of acetylene, two regulators, two lengths of hose with fittings, and a wielding torch with assorted tips. You will also need a spark lighter to light the torch, goggles to protect your eyes, a welding table with a firebrick top, and clamps to hold the work. You should wear gloves to protectyour hands.
To braze, you need a brazing rod, usually of copper alloy or silver, and a matching flux. Rods and fluxes are available for brazing on many types of metals and at many temperatures.


Welding
Remember to at in brazing, toe metal work-pieces are not melted. They are heated red hot and toe bronze rod is melted to form toe joint. In welding, toe metal workpieces are melted together. The welding rod supplies filler­metal to produce a smooth, even, strong joint.
To begin welding, light toe torch as you did when brazing. Place toe two metal workpieces so that toe edges to be joined are touching.
Start about '/₈” from toe end. Move toe torch back and forth in a slight arcuntil toemetal melts and tacks together. Tack toeotoer end.
Next, start at one end. Move toe torch to toe other end and back with a slight zigzag motion until toe metal begins to melt, forming a small puddle. Stick toe welding rod into toe puddle as needed. Move toe torch along as fast as toe metal will melt to form a smooth, even bead.