Brazing is one of the processes for combining two or more pieces of material together with a filler metal. It is primarily applied to metalworking. Brazing is a popular joining method that widely used in different industries and applications due to its high flexibility, reliability, and integrity to which the joints that produced. Common applications ranging from HVAC / automobile air conditioning systems to high sensitive satellite components and fine jewelry. Brazing is suitable to apply on a wide range of material types such as steel, copper, aluminum, silver, nickel, and gold. The key advantage of brazing is it can join dissimilar base materials without melting or distorting the physical properties of the base materials. The filler metal is normally alloyed with other elements to obtain desired performance and properties. During the brazing process, the heat will be broadly applied to the base materials, the filler metal is then placed in contact with the heated parts and it melts instantly to create a brazed joint between the base materials. The brazed joint is relatively strong and made at a low temperature. The filler metal melts at a temperature within 450 degrees Celsius and 870 degrees Celsius, and a metallurgic bond is created through the diffusion of the filler and base materials.
What are the differences between brazing, welding & soldering?
The main difference between these three techniques is the temperature they use to create the joint. Firstly, brazing does not involve melting the base materials. The brazing temperature is lower than the melting points of the base materials. Instead of fusing the base material, it melts the filler metal to bond the surface of the two materials. The liquid filler metal wets the base materials to create a joint through the principle called Capillary Action. We can conclude that the temperature used in the brazing process is much lower than the temperature used in the welding process. In contrast, the welding process involves melting the base materials to create a firm bond and it may not include the use of filler metals. Soldering is the same as brazing as it melts the filler metal but not the base materials. However, the soldering process has a lower temperature of below 450 degrees celsius and requires less power input when compared to brazing and welding.
Welding provides the strongest joint among the three processes. It is suitable for high-temperature applications and able to join thin and thick sections of the materials. But welding produces more thermal distortion and residual stresses than brazing and soldering, It is only able to join similar base materials for most of the processes. Whereas brazing and soldering can join dissimilar base materials. Soldering provides the least thermal distortion and residual stresses on the joints. It is suitable for joining thin-walled parts and widely used in electronic or piping works. In comparison with welding and brazing, soldering produces the lowest strength of joints and it is not suggested to use for load-bearing application, high-temperature, or large sections joining.
Types of Brazing
Brazing is classified by the process and equipment required to be used. Here we will introduce a few common types of brazing.
1. Torch Brazing is popular as it has low investment cost and suitable for joining small pieces items in low volume production or specialized operation. The torch is using fuel gas to create the heat, it produces bluish to white flame with a bluish to orange tip. The fuel gas can be propane, hydrogen, or acetylene and combined with the air or oxygen to create the flame. Torch brazing can be done manually, automatically, or with the use of machines.
2. Induction Brazing is clear, precise, fast with a tight tolerance that is suitable for localized or selective heating. It uses electric coils to heat the part accurately and primarily used for copper and silver-based alloys.
3. Furnace Brazing is a semi-automatic process that is widely used for mass production and unskilled workers due to its flexibility and ease of use. This process has a controlled heat cycle to control the stage of the heating and cooling cycle accurately. It can produce a large number of small parts which are self-localized and self-detecting easily. It also does not require any post-brazing cleaning.
4. Vacuum Brazing is performed under a vacuum chamber vessel that can maintain the temperature and eliminate many problems encountered in welding or brazing. It offers a number of key advantages over other types of brazing. Vacuum brazing is extremely clean, flux-free, and able to provide the highest level of integrity and strength. The mechanical and thermal properties of the workpieces also can also be improved with this brazing process. However, the process can be costly due to the complexity it is carried out.
5. Silver Brazing is using silver alloy-based filler for the brazing process. It is known as hard soldering and used in the hard metal tool industry for fastening hard metal tips to tools.
6. Dip Brazing is particularly used for brazing aluminum as the air is excluded from the process to prevent the formation of oxides. The parts that joined are fixtures and the brazing compound is in slurry form when applying to the surface.
Disadvantage of Brazing
There are some disadvantages of brazing we need to consider when selecting it for the application. Firstly, the strength of the joint is lower than a welded joint because softer filler metal is used for brazing. Even the joint is most likely stronger than the filler metal but it is not as strong as the base materials. The brazed joint also easier to be destroyed under a high-temperature environment. Secondly, the brazed joint requires high metal cleaning in an industrial setting, with the flux to clean the surface before the brazing takes place. Lastly, the color of the joint may be different from the base material as a different type of filler may be used for the process, this has created an aesthetic disadvantage on the brazing.
MecHero Malaysia offers different types of brazing, welding, and soldering process for meeting your project requirements. You can always contact us at +6011-7000 7687 or email us at my.mechero@gmail.com for an inquiry about the fabrication and engineering services in Malaysia for industrial usage. As a steel and online hardware store Malaysia, we also supply a wide range of steel materials, general hardware, or mechanical components. Tell us your requirements now and we can advise you accordingly.
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