Our Attitude Decides Our Altitudes Joining Processes Introduction

"Our Attitude Decides Our Altitudes" Joining Processes

Introduction a. Permanent joining process It is done by fusing the metal together. The metal is heated to its melting state and then it is fused to become one unit. Ex. Welding, soldering and brazing b. Semi – permanent or temporary joining process In this the metal is not heated. Process is carried out at room temperature. Temporary joining process can be done using nuts, bolts, screws and adhesives. "Our Attitude Decides Our Altitudes" • Joining process is where two or more pieces of parts are joined together to produce a single product of required shape and size. • The joining process can be classified as

Welding Process • Technical definition of Welding “a localized coalescence of metals, wherein coalescence is obtained by heating to suitable temperature, with or without the application of pressure and with or without the use of filler material. This filler material has the melting point same as the base material. ” It is also know as a metallurgical joining process of two metal pieces, to produce a single piece of product. "Our Attitude Decides Our Altitudes" • Simple definition of welding "joining metals through heating them to a molten state and fusing them together. “

• Base Metal – Work pieces that are needed to be joined • Weld Bead - A weld bead is a weld deposit produced by a single pass of the welding processes. It is also known as bead • Puddle – The molten base metal at the joint during the welding operation • Weld pass – Movement of weld torch from one end of the joint to the other end. • Tack Weld – it is the temporary joint done before welding to keep the work pieces to be welded in place during welding. The joints are done at the ends of the work piece. "Our Attitude Decides Our Altitudes" Welding Terminologies

The welding process can be classified based on the source of energy to heat the metal and the state of metal at the joint. • Pressure Welding • Fusion Welding "Our Attitude Decides Our Altitudes" Classification of Welding Process

Pressure Welding • Depends on the application of pressures and temperature • ISO – 857 defines “Welding in which sufficient outer force is applied to cause more or less plastic deformation of both the facing surfaces, generally without the addition of filler metal. Usually, but not necessarily, the facing surfaces are heated in order to permit or to facilitate bonding” "Our Attitude Decides Our Altitudes" • The surfaces of the joint to be welded is heated to a plastic state and forced together with external pressure to finish the joint.

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• Heating in to molten state and allowed to solidify to form joint with or without the addition of filler material. • The process is carried out with out the application of pressure. • ISO – 857 defines “Welding without application of outer force in which the facing surface must be melted. Usually, but not necessarily, molten filler metal is added”. "Our Attitude Decides Our Altitudes" Fusion Welding

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Advantages • Strength of the joint obtained in welding is much stronger than the parent metal • Welding produces stronger joints. Hence this process is used for fabrication and structural applications "Our Attitude Decides Our Altitudes" • It is a high temperature process where the base metals are heated above their melting temp.

Disadvantages • Since welding is carried out at high temp, the metal adjacent to the weld portion called the heat affected zone which is affected to a large extent "Our Attitude Decides Our Altitudes" • Requires certain finishing operations like grinding , filing etc

Applications üFabrication of automobile cars , Air- craft, Refrigerators, Pressure vessels , Furnaces etc üRepair and maintenance work Joining broken parts Rebuilding worn out components etc "Our Attitude Decides Our Altitudes" It can be employed in industry as a tool for,

Brazing • it is a method of joining two similar or dissimilar metals using a special fusible alloy called as “Spelters”. which is non ferrous metal or alloy "Our Attitude Decides Our Altitudes" • The base metals do not melt; they are heated above 450 deg C but below their melting temperatures of base metal. • Some diffusion of the filler metal with base metal takes place. • There are two types of spelters used: • Copper and Copper base alloys • Silver and silver base alloys

Lap Joints Lap joint is the type of joint that have a larger surface area because it is formed by overlapping of two metals. Butt-Lap Joint It is a combination of both butt and lap type of joint and offers the advantages of both. Butt-lap joint give the profitable features of single thickness as well as of maximum strength "Our Attitude Decides Our Altitudes" Butt Joint When two metals are positioned in a head-to-head arrangement for brazing, it will result in a Butt joint.

• Dissimilar metals and parts having thin sections can be joined easily. • Brazing may avoid the metallurgical damage to the base metals. • Strong joint can be obtained by brazing. • It is economical and quick process • Less heating is required than for welding. "Our Attitude Decides Our Altitudes" Advantages

• Soldering is a method of uniting two thin metal pieces using a dissimilar metal or an alloy by application of heat. • The alloy is called as solder. • Two types of solder are: • Soft solder • Hard solder • Usually the base metal is heated upto around 350 deg C. • Soldering is usually used for electrical & electronic works and some low end sheet metal work. "Our Attitude Decides Our Altitudes" Soldering

Hard soldering use higher temperatures, typically requiring a flame or carbon arc torch to achieve the melting of the filler. Hard soldering, as used by jewelers, machinists and in some plumbing applications, requires the use of a torch or other high temperature source and is much stronger than soft soldering. "Our Attitude Decides Our Altitudes" Soft soldering is characterized by having a melting point of the filler metal below approximately 400 °C (752 °F). Soft solder filler metals are typically alloys (often containing lead) that have liquidius temperatures below 350°C. Soft soldering can be done with a heated iron whereas the other methods require a higher temperature to melt the solder than can be achieved with a heated iron.

• It is simple and economical process • Since it done at relatively low temperature, no metallurgical damage to the base metal. • The soft soldered joints can easily be dismantled by simple heating • Operator fatigue is less compared to welding process. • • DISADVANTAGES 1. The process is limited to minimum thickness (3 mm) 2. Skilled operator is required. 3. Strength of joint when compared to welding is low. "Our Attitude Decides Our Altitudes" ADVANTAGES

Sl no Brazing Soldering 1 Melting point of the filler material is about 600 degree. Melting point of the filler material is below 450 degree. 2 Dissimilar metals can be joined easily. Only similar metals can be joined. 3 Good surface finish. Does not yield a good surface finish 4 Stronger joints. Less stronger joint. 5 It is used for production of It is used for electrical and heat exchangers and radiators. electronic applications. "Our Attitude Decides Our Altitudes" Difference between Soldering and Brazing

Difference between Welding , Brazing and Soldering welding brazing soldering 1 Temperature Very high, about more than 5000 degree c Melting point of the Melting point of filler metal is above the filler metal is 600 degree c below 450 degree 2 Type of metal to be joined Only similar metals Dissimilar metals Only similar metals 3 Surface finish moderate good poor 4 strength Very high weak "Our Attitude Decides Our Altitudes" Sl no Parameter