What Are Brazing Rods?

Brazing is an effective thermal joining process commonly used in engineering. It is often preferred over other process like welding. Brazing can join almost all the metals and alloys. In this process, a molten brazing alloy is drawn into a capillary gap between the metals being joined. Many forms of brazing alloys are used for fulfilling this requirement. Brazing rods are perhaps the most popular forms of brazing alloys used world over by professionals.

What is a Brazing Rod?

Brazing rod is a piece of metal in the shape of a rod. It melts during the brazing process and attaches to the separate pieces of metals in order to join them together once cooled.

What are the Metals Used for Making Brazing Rods?

Brazing process has the ability to join different metals and components of dissimilar size and mass. However, for this, the perfect form of brazing alloy (filler metal which melts above 450˚C but below the temperatures at which metals being joined melt) has to be present. Therefore, brazing rods have to be made from different metals like aluminum, silver, steel, bronze etc.

What is Flux Coated Brazing Rod?

There are many types of brazing processes which are conducted in different atmospheres. In the one which is not contained within an inert or reducing atmosphere environment (for example a furnace,) flux is needed to prevent oxides from forming when the metal is heated. Not only this, flux also cleans up any contamination that is left on the brazing surfaces. Flux too comes in various forms like flux paste, liquid, powder or pre-made brazing pastes that combine flux with filler metal powder. Sometimes, flux is applied to brazing rods either in the form of a coating of flux or a flux core. This flux flows into the joint when the brazing rod is applied to the heated joint and is displaced by the molten filler metal entering the joint.

To know more about brazing rods as well as other forms of brazing alloys, read Brazing Rod

How to Choose Right Brazing Alloy?

Choice of the right form of brazing alloy is one of the most important issues which affects the integrity of any joint assembly- other factors being joint design and proper fit; cleaning procedure to prepare surface; fluxing practice; proper cooling and flux removal; and method of heating. So, how to choose just the right form of brazing alloy? Let's know about it.

Some Criteria to Choose Brazing Alloy!

A brazing alloy is the metal which is added during the brazing process in order to complete a joint. Melting range for a brazing alloy has been defined by the minimum temperature at which the alloy starts melting (“solidus”) and the temperature at which the alloy becomes liquid (“liquidus”). For most purposes, the actual brazing temperature lies within 50°F to 200°F (30°C to 110°C) above the liquidus. While the melting range depends upon the chemical composition of alloy, it is also important to note that individual batch characteristics may differ slightly. Some alloys have a very narrow melting range and others have a relatively wider range. Those having narrow melting range are used for filling very narrow gaps while others with wider range are better used for filling larger gaps.

There are many forms of brazing alloys. Different alloy combinations change the melting temperatures as well as other properties of brazing alloy. However, a brazing alloy should fulfill the following basic criteria.

• It should flow evenly across the surfaces of the base metal, and through capillaries even if they are as small as 0.001-inch;
• It should resist alloy separation into solid and liquid phase during brazing.
• It should provide a strong bond by partially alloying with the base metals.
• It should meet conditions of corrosion resistance, ductility, thermal and electrical conductivity, or other desired properties.

High temperature brazing alloys like gold, nickel and copper can be used for brazing multiple joints at a time but care must be taken with the joint design and joint clearance. In such cases, heating time should be minimized to the time needed to bring all components to the heating temperature and for the molten alloy to flow quickly. high temperature brazing should be used for joining cobalt or nickel-based superalloys.

Comparison of Popular Brazing Alloys

Although copper, nickel and silver are the most frequently-used base metals for brazing alloys; aluminum and gold are also used for some brazing applications.

Brazing Alloy	Brazing Temperature	Joint Clearance	Benefit
Copper	2000° F	interference to 0.002”	Joint Strength, Low Cost
Silver	1300° F	0.002-0.005”	Low Temperature
Silver with Lithium	1300° F	0.002-0.005”	Low Temperature, Self-Fluxing
Nickel	1900° F	0.002-0.008”	Joint Strength, Resistance to Corrosion
Aluminum	Column 21080° F	0.002-0.01”	Only braze for aluminum
Gold	1800° F	0.002-0.008”	Resistance to oxidation and corrosion

Most of the above mentioned brazing alloys are generally available in various forms like wire, foil, tape, powder and paste. Know about all such forms of brazing alloys.

How is Brazing Done?

Brazing, as people dealing with metals would know, is a process of joining metals (and non metals too.) There are different techniques for joining metals through brazing which are known as brazing processes but there is a common basic working principle for all these processes.

Basic Brazing Process

For brazing, a Braze Filler Metal (BFM) is used. Most brazing filler metals are alloys, or combinations of pure elements or materials. The filler metal must have a melting temperature above 840°F (450°C) but below the melting point of the base metals or the metals that need to be joined.

In brazing process, the base metals are heated, generally to a point that is slightly above the liquidus (liquidus is the temperature above which an alloy is completely molten. When an alloy exceeds the liquidus temperature, there are no solid phases present.) of the filler metal, causing it to melt. As a result, the filler metal flows into the parallel joint clearance between the two base materials by capillary attraction and bonds to their surfaces through atomic attraction and diffusion.

Thus, the basic principle through which brazing works is by joining the base metals by creating a metallurgical bond between the filler metal and the surfaces of the two metals being joined. However, there are certain differences in this basic technique of joining metals when we refer to different types of brazing processes.

Brazing Procedure

For an effective brazing, some conditions have to necessarily fulfilled. If not then problems associated with brazing occurs. Thus, the following conditions should be there:

• Good fit and proper clearance
• Clean base metals
• Proper fixturing
• Proper fluxing and atmosphere
• Heating the assembly
• Cleaning the brazed assembly

All these can be attained by following proper brazing procedure. To get step by step instructions about how to do brazing, read Basic Brazing Procedures

Brazing Versus Soldering

Brazing and soldering are two processes meant to serve the purpose of bonding two dissimilar metals. A joining filler metal or alloy is inserted between the two metals, in molten form and then heated at a high temperature. The only difference between the two processes by definition is that brazing is carried out at higher temperatures as compared to soldering. Accordingly for brazing the filler metal being used should have a liquidus temperature of above 840 degrees Fahrenheit or 450degrees Celsius, whereas in soldering the liquidus temperature of below 840 degrees Fahrenheit.

Apart from the above difference, the differences in these two processes are marked by a difference in the requirements of braze joints. The strength levels required, the design specifications demanded, all these determine what process is a more suitable.

To have a closer look at the two processes, make a comparative analysis on various criteria like cost effectiveness, flexibility, strength and process control, and to be able to make a judgment regarding which process is suitable for what kind of joints needs, read the complete article.

Brazing Filler Metal Rods: Types & Applications

Brazing filler metals are found in variety of forms to suit different types of brazing needs. The surface area of the metals to be joined might not always be in the same shape. It might be simple or complex as per the need of the braze joint. Most found and used forms of brazing filler metals are brazing paste, brazing wires, brazing sheets, brazing foils, brazing rods, and brazing powders. Each of these are used in different situations.
To understand the types of brazing filler metal rods, the metals in which they are available, what brazing needs are they suitable for and a look at their industry applications, read the complete article.

Forms Of Brazing Alloys

Brazing alloy or the filler metal is the metal that is used to join two different metals through the brazing process. Filler metal is the metal that goes into the space between the two metals to be joined, melts in there and then flows down the joining surface before it goes through brazing. This makes it a strong joint between two dissimilar metals. It is very much like welding and soldering, but different than these processes in a lot of aspects. All three processes have different advantages, disadvantages and therefore different applications.


Coming back to brazing alloys or the filer metals, the choice of brazing alloys differs from metal to metal. Base metal characteristics need to be matched with the filler metal metals properties to ensure that they are chemically compatible. This is important for two reasons. One, safety in brazing. Two, achieving desired results from the process. The commonly used brazing alloys are aluminium, nickel, steel,titanium,copper, brass, etc.


Just like the careful choice of the properties, choosing the suitable form of the brazing alloys is also of key importance. Brazing alloys are available in quite a few forms that are useful in different metal brazing. To ease out brazing of different types of metals, different forms of brazing alloys, namely – paste, powder, rods, sheets & wires. Other shapes available are rings and discs.


Choosing the filler metal as well as the suitable form is dependent on the base metals being used for the brazing application and the shape of edges to be joined. Different shapes are used to fit them well in place in between the gap. For, example the wire, strip and rod forms are for face feeding, where as the brazing alloy paste is used because of its ease of applying in complex shapes of joints. Similarly using a powder form of alloy also does away with any limitations with respect to the shape of the joint.

Guide For Choosing A Suitable Brazing Atmosphere

Brazing atmosphere refers to the atmosphere around the metals while they undergo the brazing process. There are broadly 3 types of brazing atmospheres that have their own advantages and disadvantages. Each of them works differently and gives different results. What atmosphere can be managed with what resources, is an important piece of information that you need before you actually go in for a particular brazing atmosphere.

Although some people categorize the brazing atmospheres in 4 heads - open atmosphere, protective inert gas (i.e Argon, Nitrogen and Helium), reducing gas (i.e Hydrogen, Carbon Monoxide, dissociated Ammonia) and vacuum brazing - we would cover all of them, but under three category headings, namely: Open Air, Controlled and Vacuum brazing atmospheres. To understand each of these in detail read the complete article.