When is Brazing considered suitable over Welding?
What is Brazing?
It is the process by which two metals are joined together by using a molten filler or alloy that connects them. The melting temperature of the alloy used as a filler material should be around 450°C and always lower than the metals that are to be joined. The melted alloy filler requires a specific environment or atmosphere, for instance, a furnace, and needs to be protected by a material called flux which prevents the molten alloy from oxidation and lets it flow over the metals that are being joined. An example of such a material is borax. The dissimilar metals that can be joined by brazing include aluminum, gold, silver, copper, and nickel.
The alloys that can be used as fillers include aluminum-silicon, copper-silver, silver, gold-silver, copper-zinc, etc.
There are two methods that are used in the brazing process
- 1.Localized Heating: In localized heating, only the ends of the metals that are to be joined are heated. Localized heating is done by using three different techniques:
- 2.Diffuse Heating: In diffused heating, the complete metal objects are heated for the purpose of joining the pieces of metal. Diffused heating is done by using two different techniques:
- Torch brazing is done by using a torch or fueled gas flame that can be acetylene, propane, or hydrogen mixed with oxygen. This is a cost-effective method and requires flux which joins the metals by melting.
- Induction is a technique in which a coil is used to induct high-frequency heat for brazing by swiftly alternating an electric current.
- Resistance technique is used for joining metals that have electric conductivity. Heat is produced by resistance to electric current flow in the form of a circuit that consists of the metals in order to melt the base metals that are intended to be joined.
- Furnace is a technique used for heating and the temperature can be easily controlled at each stage of the process of joining the metals.
- Dip brazing is a technique in which complete metal objects that are supposed to be joined are dipped into the molten flux or brazing alloy. In this technique, it is important to ensure that the melting point of metals to be joined should be higher than the melting point of the molten alloy.
Brazing is considered suitable for joining two different metals because of its flexibility and reliability. It is one of the most commonly used methods of joining metals which is used commercially by several different industries.
What is Welding?
Welding is a technique used for joining two similar metals and thermoplastics. Welding involves the use of high temperatures and pressure to join the metal. If done properly it can form a strong joint. The welded joint is called weldment. The objects that are supposed to be joined are called parent parts and the filler is used to join the parent objects.
There are different resources used for welding such as electric arc, electron beam, ultrasound, gas flame, laser, or friction. It can be performed efficiently in different environmental conditions such as underwater or open air. Proper ensemble, gloves, and masks are needed to perform the task for safety purposes.
Types of Welding
- TIG: TIG stands for Tungsten Inert Gas. It is a welding technique that requires special skills because it is difficult to perform. Both hands are used while performing this welding method. It is performed with the help of a TIG torch and a non-consumable electrode having Tungsten for forming an arc.
- MIG: MIG stands for Metal Inert Gas. It is the most widely used technique of welding and can be learned easily. It is performed with a stick or a gun with a consumable electrode current wire forming an arc.
- SMAW: SMAW is an abbreviation for Shielded Metal Arc Welding and also known as stick welding. It is performed with the help of an electrode rod. It is a cost-effective and widely used way of welding despite producing a weak weldment.
- Plasma Arc: It is a welding technique that requires precision. In this technique, an electrode is lowered to produce heat by ionizing gases.
- FCAW: FCAW is an abbreviation for Flux-Cored Arc Welding. It is performed by using a consumable electrode having a flux at the core.
- Electron beam and Laser: An electron beam or laser is used to produce heat in order to melt the materials for the purpose of welding them.
- Gas: In this technique, oxygen and acetylene are used to produce a flame for the purpose of joining the metals.
Brazing Versus Welding
Brazing forms strong bonds between metals but not as strong when compared to welded joints. Brazing has little to no impact on the parent materials. In the following table, we will compare welding and brazing
It works well for parent metals having around 0.5inch thickness or more but not suggested for thinner parent metals.
It works well for parent metals that are thinner as well as thick parent metals ranging from 0.005inch to thicker parent materials around 0.5inch or more.
Welding is considered more suitable for large-size assemblies because localized heat makes it easier to reach the point where the filler alloy requires heat.
It is not considered for large assemblies because it tends to dissipate heat which makes it difficult to reach the point where the filler requires the heat for joining the parent material.
Welding is suitable when joining similar metals or materials.
Brazing is considered suitable for joining dissimilar metals.
The welding process is suitable for spot joints and more preferred because concentrated heat makes it easy to target a single point more easily and economically.
It is suitable for spot joints as well as linear joints. For linear joints, welding requires more effort and time than brazing because it does not require manual tracing as welding.
Welded joints usually require additional working to improve its outlook because it produces irregular beaded metal joints.
Brazing is preferable if appearance is the main concern. Brazing does not require additional finishing and produces a neat brazed joint.
Volume of Production
Welding can be done manually as well as automated but manually it can weld one unit at a time and automation requires installations of expensive equipment. It offers extreme options only.
Brazing offers various options of automation for small, medium, and large production volumes.