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Introduction to Brazing

Brazing is a welding process that is used to join two pieces of base metal using melted filler which flows across the joint.  When the filler metal cools, it creates a solid weld between the two pieces of metal.  The process of brazing is similar in nature to that of soldering, and brazing forms a very strong welded joint which tends to be stronger than either of the base metals on their own.  Brazing allows welders to create a strong weld and does not cause the base metals to melt or lose their shape while the process is being completed.  The process of brazing is commonly used when the welder needs to create a joint that is invisible to the naked eye, yet strong enough to hold up in a variety of temperatures.  Joints that are created using the brazing technique are often pliable and can withstand jolts and twisting. 

The technique of brazing is somewhat similar to that used in soldering except that the temperatures that can be used with either method differ.  Brazing can be used to join pipes, rods, metals of a flat nature or any other shape of metal as long as the two pieces being joined fit snugly against each other without any large gaps.  Brazing can also be used to join unusual combinations that feature linear joints.

Before beginning to braze a welder must clean the entire area of the metals that are going to be joined, otherwise the melted brazing mixture will become lumpy and not flow as it should which will result in the formation of an inconsistent joint.  To avoid the formation of inconsistent joints, you should clean the surfaces of the metals and then apply melted flux.  Flux is used to remove oxides and prevent further oxidation while the brazing is being performed.  Flux also smoothes the surface to allow the braze to easily flow over the joint.

Once you have thoroughly cleansed the metal pieces you will be working with, you will need to gather the tools you will be working with.  This includes preparing your work area and preparing your torch and the braze alloy you will be using.  The torch that is used in brazing can use gases like acetylene and hydrogen to produce an extremely high level of heat typically between 800 and 2000 degrees Fahrenheit.  It is important that the temperature be low enough not to melt the base metal but hot enough to melt the filler metal being used to create the joint.  The temperature of your torch can be adjusted using the controls to reach the correct temperature. 

After you have cleaned the base metals and set your torch at the appropriate temperature, you are now ready to begin brazing.  Braze can be purchased in either a stick, disc or wire form.  Depending on which type you prefer to work with or the shape of the joint you will be creating, there is a form of braze that will work.  Once you have heated the base metals near the location of the joint you will be forming you will want to bring the wire to the hot pieces and allow the braze to melt and flow around the joint.  The term flow refers to the braze penetrating the joint and settling into all areas of the joint.  When a braze is done in the correct way, the result will be a bond that is virtually indestructible.

There are many advantages to using brazing over spot welding or soldering.  A brazed joint tends to be smooth and complete and creates an airtight and watertight bond.  Brazed joints can also conduct electricity in the same manner that the base metals were able to.  Brazing can also be used to join metals that are dissimilar in nature.

Ed

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