The soldering
Soldering is a process in which two or more metal items are joined together.
The soldering technique is the most used technique for the fixation of prefabricated dental attachments.
The soldering can be divided in:
- welding: the joining together of two pieces of the same metal without the introduction of a solder as termed “autogenous soldering”. That is the case, for example, of laser welding;
- brazing: the joining of two metals by the fusion of filler alloys that are of a lower melting temperature. The filler metal used in the process is called solder. If the melting point of the filler metal is:
- below 400 °C ÷ 450 °C (750 ÷ 840 °F) the technique is called soldering.
- above 400 °C ÷ 450 °C (750 ÷ 840 °F) the technique is called blend brazing.
In a soldering process, heat is applied to the parts to be joined, causing the solder to melt and be drawn into the joint and to bond to the materials to be joined by wetting action. After the metal cools, the resulting joints are stronger than the base metal.
The soldering is the most used procedure to fix prefabricated attachments and usually for:
- Primary part, we use a method called braze soldering, where the filler metal is not distributed by capillary action, but is applied to the joining metals from a welding rod during the heating phase.
- Secondary part, we use a method called capillary brazing, that implies that the solder is inserted between the parts to be joined before starting the heating. In brazing, the filler metal is drawn into the joint by capillary attraction. When heat is applied, the metal flows by capillary action into the gap between the base metals or materials and joins them by creating a metallurgical bond between them at the molecular level.
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