|
Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Soldering differs from welding in that soldering does not involve melting the work pieces together but rather in brazing the filler metal melts at a higher temperature, but the work piece metal does not melt.
Silver soldering.
"Hard soldering" or "silver soldering" is used to join precious and semi-precious metals such as gold, silver, brass, and copper. The solder is usually referred to as easy, medium, or hard. This refers to its melting temperature, not the strength of the joint. Silver has a melting point of 618 °C. If multiple joints are needed, then the jeweller will start with hard solder and switch to lower temperature solders for later joints.
Silver solder is absorbed by the surrounding metal, resulting in a joint that is actually stronger than the metal being joined. The metal being joined must be perfectly flush, as silver solder cannot normally be used as a filler and any gaps will remain.
Another difference between brazing and soldering is how the solder is applied. In brazing, one generally uses rods that are touched to the joint while being heated. With silver soldering, small pieces of solder wire or plate are placed onto the metal prior to heating. A special flux is used to keep the metal and solder clean and to prevent the solder from moving before it melts.
When silver solder melts, it tends to flow towards the area of greatest heat. Jewellers can somewhat control the direction the solder moves by leading it with a torch; it will even run straight up along a seam.
|