brazing and soldering

SOLDERING AND BRAZINGSOLDERING AND BRAZINGSOLDERING AND BRAZINGSOLDERING AND BRAZING

ME ME 473 WELDING 473 WELDING TECHNOLOGYTECHNOLOGY

Yrd.Doç.DrYrd.Doç.Dr. OĞUZHAN YILMAZ. OĞUZHAN YILMAZ

Department of Mechanical Engineering The University of Gaziantep

� Brazing is a liquid phase process, whereby molten filler metal (the braze) is drawn into the gap between closely adjacent surfaces by capillary attraction

� In general, the melting point of the filler metal is above 450°C, but always

below that of the parent material. � To achieve a perfect joint, the filler and parent materials should be

metallurgically compatible and the design of the joint should incorporate a

gap into which the braze filler metal will be drawn.

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gap into which the braze filler metal will be drawn.

� There are many ways of brazing, and they all include the method of applying heat:

� Dip brazing

� Furnace brazing

� Induction brazing

� Infrared brazing

� Resistance brazing

� Torch brazing

� Others…

�The processescan be carried out under vacuum, inert gas or by using fluxes.

Dr. Oğuzhan Yılmaz

Brazing: MethodsBrazing: Methods�� Furnace Brazing:Furnace Brazing:

� This process is accomplished by placing cleaned parts in a furnace. � The parts should be self-jigging and assembled, with filler materials preplaced

near or in the joint. The preplaced brazing filler material may be in the form of wire, foil, fillings, slugs, powder, paste, tape, and so on.

� The furnaces are usually heated by electrical resistance. Automatic temperature controllers are required so that they can be programmed for the brazing temperatures and cooling.

� Flux is employed except when an atmosphere is specifically introduced in the furnace to perform this function. Flux should not be used where postbrazed cleaning is made difficult by the complexity of the design of the brazed parts.

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cleaning is made difficult by the complexity of the design of the brazed parts. � Furnace brazing is often done without the use of flux by the use of special

atmospheres (hydrogen and other special gases – helium and argon-) in the brazing furnace.

Furnace Brazing


Brazing: MethodsBrazing: Methods�� Resistance Brazing:Resistance Brazing:

� The heat is obtained from the resistance to

the flow of an electrical current through the parts being brazed. The parts become a part

of the electrical circuit through electrodes made of copper alloys or carbon-graphite.

� Alternating current is normally applied.

� The parts to be brazed are held betwen the


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The parts to be brazed are held betwen the

two electrodes while the correct pressure and electrical current applied. The pressure is

maintained until the filler metal has solidified.

� Resistance brazing is normally used for low-volume production where heating is localized

at the area to be brazed. It is also limitted to

applications where the brazing filler metal is preplaced.


Brazing: MethodsBrazing: Methods�� Torch Brazing:Torch Brazing:

� It is done by heating the parts to be brazed with the flame of a gas torch or torches.

� The temperature and the amount of heat

required determine the gas used.

� Torch brazing is very useful on assemblies that

involve heating sections of different mass.

� Manual torch brazing is particularly useful for


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� Manual torch brazing is particularly useful for

repair work.

� The neutral or reduced flame is normally used.

� The brazing filler metal may be preplaced in or

it may be face-fed manually.

� Torch brazing is used when the part to be

brazed is too large, is an unusual shape, or

cannot be heated by the other methods.


Brazing: Filler metalsBrazing: Filler metalsFiller Metals:

� Aluminium-silicon, copper, copper-zinc, copped-phosphorus, nickel-gold, heat-resisting materials, magnesium, and silver.

� Filler metals are available in many forms; the most common is the

wire and rod. They are also available in thin sheet, powder, paste,

or as a clad surface of the part to be brazed.

� Base metal and the compatible filler metal:


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� Base metal and the compatible filler metal:

Base Metal Filler Metal

Aluminium Aluminium and Silicon

Nickel-Copper alloys Copper

Copper Copper and phosphorus

Steel and cast iron Copper and zinc

Stainless steel Gold and silver


Brazing: FluxesBrazing: Fluxes

Fluxes:

� The flux is chosen according to the material to be brazed and the temperature range.

� Flux in powder form is usually used for furnace brazing.

� Paste flux is usually used for torch brazing.

� Placement of the flux affects the quality of the brazed joint.

� Functions:� Remove oxides from the surface chemically


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� Remove oxides from the surface chemically

� Avoid oxidation during preheat

� Helps to decrease the surface tension of the molten filler metal so that it can flow and spread over the surface easily

� Reduce the cooling time

Uses:Uses:

� Three major industries using brazing are the electrical industry, the utensil-manufacturing industry and the maintenance and repair industry


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Brazing: QualityBrazing: Quality

� It is important to have extremely clean surfaces for the brazed joint. Mechanical

surface preparations such as grinding, sandblasting, wire brushing, filing, and

machining can be used.

� The surface must be clean and removed from dust, oil, etc.

Throubleshooting hints:Throubleshooting hints:

� If the brazing filler metal does not wet the surface:

� Increase the amount of flux used

� Roughen the surface


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� Roughen the surface

� Change the work position so that the gravity will help the filler metal fill the joint

� If the brazing alloy does not flow through the joint

� Allow more time for heating

� Heat to a higher temp

� Apply flux both the base metal and brazing filler metal.

� If the brazing filler metal melts but does not flow

� Coat the filler metal with flux

� Mechanically and chemically clean the filler metal if there are surface oxides present.


Soldering: IntroductionSoldering: Introduction

� Soldering is a group of processes that produce coalescence of material by heating

them to the soldering temperature and by using a filler metal having liquidus not

exceeding 450ºC and below the solidus of the base metals.

� The filler metal is distributed between closely fitted fying surfaces of the workpieces.

� Solder is a filler metal used in soldering that has liquidus not exceeding 450ºC. It is

normally a nonferrous alloy.

� There are at least eight popular soldering methods in wide use:


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� There are at least eight popular soldering methods in wide use:

� Dip soldering

� Furnace soldering

� Induction soldering

� Infrared soldering

� Iron soldering

� Resistance soldering

� Torch soldering

� Wave soldering etc.


Soldering: MethodsSoldering: Methods

Furnace Soldering:Furnace Soldering:

� It is a soldering process in which the parts to be joined are placed in a furnace and heated to the soldering temperature.

� In furnace soldering the parts must be assembled and fixed in their proper position.

� The solder must be preplaced in the joint.


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Resistance Soldering:Resistance Soldering:

� It is soldering process that uses heat from the resistance to the electric current flow in a circuit of which the workpieces are a part.

� This is a very common method of manufacturing electrical machineryinvolving soldered joints

� The solder is applied manually and also used for soldering copper plumbing fittings.


Soldering: MethodsSoldering: Methods

Torch Soldering:Torch Soldering:

� It is very similar to torch brazing except that lower temperatures are involved and air is used rather than oxygen.

� The solder is manually applied.

� Torch soldering is widely used in the plumbing trade for soldering copper tubing to copper fittings.


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Soldering flux:Soldering flux:

� The flux helps to remove oxide, but the flux must be designed so that it can be removed after the joints in soldered.

� It should be fluid at a lower temp than the liquidus of the solder

� It should have a lower specific gravity than the solder so that the solder will displace it in the joint.

� Flux should be applied to the base metal to protect it from oxidation.


Soldering: Flux & SolderSoldering: Flux & Solder

SolderSolder

� Solders are classified acccording to whether or not they contain lead.

� The most common general-purpose solder is the 50% lead- 50% tin composition.

Solder procedure:Solder procedure:

� The joint must be properly cleaned.

� It must be free of all oil, grease, dirt, oxides, and so on.


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� It must be free of all oil, grease, dirt, oxides, and so on.

� Cleaning can be accomplished by brushing, filling, machining, sanding, and by the

use of chemicals.

� Heat is applied to the joint by many different mechanism and then the space is filled with solder.


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Soldering: ApplicationsSoldering: ApplicationsWeldingWelding TechnologyTechnology

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End of the chapter….

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Thank you

brazing and soldering

Documents

brazing filler metal

brazing temperatures

ways of brazing

methods furnace brazing

methods resistance brazing

methods torch brazing

brazed parts

filler materials