 Hello everyone, I am Chandrakant Rathod working as Assistant Professor in Mechanical Engineering Department, Valchand Instruct Technology, Solapur. Today we are going to start a new topic that is Introduction to Brazing Process and its applications. Coming to the learning outcomes, at the end of today's lecture you are able to understand what is brazing process and the application of brazing process. Coming to the content, so following topic will be discussed in this video lecture that is introduction of brazing, principles of brazing, brazing flux and filler metals, types of brazing, application of brazing and advantages and limitations of brazing process. Now coming to the introduction to the brazing process, brazing is a metal joining process in which two or more metals atoms are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the adjoining metals. So you can see the diagram in this one you will going to see job one and job two. So in between these two job and job two we have to join these two metals. So for joining this one we will going to require the flux and a high temperature flame. So that flame is taken from the welding torch and filler metal is applied in between the two base metals that is job one and job two and then the high temperature flame is applied in between the both the job to melt the flux. The flux will going to melt and the joint will going to takes place in between the two jobs. So coming to the principles of the brazing, so there are two types of brazing process that is brazing and braze welding. So first we will going to discuss what is brazing. So brazing is a liquid solid state metal joining process in which filler metal is placed in between the metal surface to be joined and heated. So as to melt only filler metal the filler metal used melts above 450 degree Celsius. The molten filler metal fills the joint cavity by capillary action and joining takes place by allowing at diffusing process. So coming to the brazing braze welding, braze welding is a process in which the filler metal is deposited at the joint using a technique similar to oxy acetylene gas welding. Thus it is similar to any fusion welding operation. The joint is formed by depositing the molten filler metal rather than the capillary action. Hence it is required more similar metals than brazing. Also a strong joint can be formed in brazing braze welding since the joint is thicker. However the melting temperature are lower in braze welding than in fusion welding. Generally braze uses a filler metal is Cu Zl alloy that is brass. You can see this diagram so as in the introduction also I explain the procedure how the welding takes place in between the two jobs. So let us consider these two jobs. So first before going to start the apply the our flux we are going to clean all the dirt and grease on the surface of the both the job and then we are going to apply the flux and after applying the flux we are going to give the high temperature flame through the welding torch. So you are going to see the flame is created in between these two jobs and only the flux is going to melt between the two jobs and not only the our jobs will not going to melt. So you can see the filler metal in between the two jobs is placed and you can see the job on and job to and a high temperature flame is produced from the welding torch. So this is how you are going to join the two base metals by the brazing process. So coming to the this diagram second diagram you are going to see there are two base metals you are going to see the lab joint in between the two base metals and in between that one base metal one and base metal two. So there is a filler metal you are going to see. So from that one the filler metal is melt by using the high temperature flame that is given by the gas torch and in the second diagram you are going to see the weld bead is formed by the brazed welding. So that is the cross section of the our lab joint base metals. So there you can see the weld bead is formed by the brazing and hence the joint is takes place in between the two jobs. So coming to the brazing flux and filler metals. So first we are going to see brazing flux. So similar to the welding a thin film of metal flux is filled in the metal to be joined in brazing metal oxide and other surface coating like dirt grease whatever they are present on the metal surface that affects the bounding quality hence flux is used to dissolve the oxide film and reacts with the surface coating to form a slag and protect the surface generally used brazing flux are made up of chemicals like borac, boric acid, borate and chlorides. For brazing at lower temperature fluoride of the alkaline metals are used. For brazing copper alloys with high phosphorus there is no need for the flux. So coming to the filler metals. The term brazing usually refers to the uses of brass that is copper and zinc alloy as the filler material to produce the joints brass with various composition is widely used to produce ductile joints in the steels which is the most common commercial application brass used as a filler material generally contains less than 60% of copper. So certain alloying elements like silicone, silver, nickel and magnesium are also added to the brass to attain the desirable properties in the joints. Now pause the video which is the flux used for brazing process. I hope you have written the answer. The flux which is used for brazing process is borac, boric acid, borate and chlorides. So coming to the type of brazing. So there are different types of brazing process as follows. So we are going to discuss starch brazing, furnace brazing, induction brazing, salt bath brazing, dip brazing and resistance brazing. So we are going to discuss one by one. So first we are going to consider the tarts brazing. The tarts brazing is mostly used in methods specially where the process is jobbing in nature and when the assembly is very large. Generally heat is produced by burning oxyacetylene gas it is it gives a high temperature and hence more suitable for brazing process. So coming to the furnace brazing. Furnace brazing is suitable for brazing large number of small to medium sized components. Usually brazing metals in the granular form or as a strip are placed at the joint and then the assembly is fit to the furnace. The furnace used may be either a batch type or a continuous type. So we are going to take the furnace brazing. So coming to the induction brazing. In this method heat is produced by passing a high frequency current through the coil placed around the workpiece. The high frequency current induce eddy current in the surface of metals. So coming to the salt bath brazing. In this process a salt bath is used as the source of heat and flux for the brazing. The parts to be joined are assembled and placed with a strip or a wire of brazing alloy at the line of joints. And the assembly is dipped in the salt bath which melts the brazing alloy and fills the joints by capillary action. The joint is get solidified as the part is taken out of the bath. So coming to the application of the brazing. So there are many applications used in the welding process to join the two base metals. So one we will going to discuss brazing is used where a tough and ductile joint is required. So wherever the tough joint is required the brazing process is used to join the two base metals. So coming to the second application a brazing also used in for joining the steels cast iron bronze and brass. So you will going to see that this brazing is also used for the joining the cast iron bronze and brass. So coming to the advantages and limitations of the brazing. First we will going to discuss the advantages. It is the simplest and fastest process for joining electrical connection. As we know that nowadays all the connections is used joined by the brazing process and this brazing process is used to join the electrical connections. So any two dissimilar metal forming an inert metal compounding with tin carbon can be joined. So it is suitable for both manual and automatic applications. So this brazing is useful for manually when joining the metal two base metals and automatically also we can join the two base metals. So it is also suitable for mass production. In industry we will going to consider that there is a mass production then we will going to use the brazing process. So coming to the limitations of our brazing process it is not suitable for the structural joints. As we know that in the structural joint so there is a more load is applied more pressure is created in the structural joint. So for that reason we are not going to use this brazing process as the in the structural joints. So it is suitable only for the low strength and thin joints. So you can see the wherever the low strength and thin joint is required there only going to we will going to use this one. These joints are not suitable for vibration and corrosion environments. As we know that there wherever the more vibration is there. So where there will not going to use this brazing process and wherever the more corrosion environment is there there will not going to use the this brazing process. So these are the some references which is taken for this lecture that is manufacturing technology by P. N. Rao and manufacturing process by one that is A. C. Niranjan. Thank you.