Soldering:
It is a method of joining two similar or dissimilar metals by means of fusible alloy or metals called solder. The melting point of filler metal is below 450°C. It is used for obtaining a leak proof joint or a low resistance electrical joint.
Soldering is of two types.
Soft soldering: It is used is sheet metal works for joining parts which are not bearing excessive loads.
Hard soldering: It is used where a stronger joint is required.
In soldering process lap joints are preferred. The composition of some of the solders is listed below.
| S. No. | Type of solder | Lead (%) | Tin (%) |
| 1. | Soft solder | 37 | 63 |
| 2. | Medium solder | 50 | 50 |
| 3. | Electrician solder | 58 | 42 |
| 4. | Plumber’s solder | 70 | 30 |