Soldering & Brazing

 Soldering & Brazing 

 Soldering and Brazing 

In soldering and brazing there is no direct melting of the base metals being joined. The strength of soldering and brazing joints is much less than the welded joints.

 Soldering 

Soldering is a method of uniting two or more pieces of metal by fusible alloy or metal, called solder. Soldering is applied in molten state. It is a quick method of making joints in light articles made from steels, copper, brass and wire joints. Soldering should not be used where much strength is required, or where the joint will be subjected to vibration [or] heat, has comparatively weak and has a low melting point.

 Types of Soldering 

Soft Soldering:

Soft soldering is the process of joining metals by the use of filler metals of low melting point [45 8°C]. The filler metal is an alloy of lead and tin. The melting point of solder should be less than base metal. Soft soldering is used extensively in sheet metal work. Flux used in soft soldering is zinc chloride.

Hard Soldering:

The filler material [solder] melts at higher temperature [650 to 7000°C] Solders having melting point over 4500°C are referred as hard solder. Silver alloyed with tin is used as hard solder. Flux used in hard soldering is borax paste. Hard soldering is a silver soldering process.

 Brazing 

Brazing is similar to soldering but it gives much stronger joint It is defined as "Ioining of two metal pieces by using a filler metal" whose liquidus temperature is above 450°C. It gives much stronger than soldering. The major difference between soldering to the brazing is harder filler material [mostly used spelter]. Spelter fuses at some temperature above red heat, but below the melting temperature of parts to be joined.

Soldering equipment:

• Soldering iron

• Soldering heater

Soldering iron:

Heated by solid or gaseous fuel or electric heater. Soldering iron consists of copper point or bit. It is usually made up of square or rectangular cross-section. A stem is made of mild steel, and wooden handle.

Soldering heater:

It is used for heating the soldering bit, for accomplishment of soldering operation.

 Advantages and Applications of Soldering & Brazing 

Advantages:

• Low cost.

• Simplicity and cheapness of equipment.

• The properties of base metal is not affected due to low operating temperature.

• Good and effective sealing compared to spot welding and rivetting.

Applications:

• Connections in wireless sets, radio, TV.

• Wiring joint of electrical connections, battery, and other terminals.

• Drain water gutters and pipes.

• Radiator brass tube for motor car.

Brazing is used to join:

• Cast metal to wrought metals.

• Non metals to metals.

• Dissimilar metals.

• Porous metal components.

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