Brazing is a method of welding where two or more metals are joining by the use of a filler metal which melts and flows to form a joint. The filler metal possess relatively lower melting point compared to base metals in order to solid base material to be maintained while the filler metal turn to liquid and fill up the intervening space. This forms a nearly watertight interface which is used in several sectors to join components for applications with keen and rigid interfaces.
In this article we will delve deeper the brazing process, learn about the different types of brazing, its benefits, usage as well as questions that people ask about the process.
How Brazing Works
Brazing involves three primary steps:
Preparation
The surfaces to be joined must be blanks and void of materials like grease, oil or oxidation layers. Correct pre-cleaning allows filler metal to wet the seam and entangle it properly, thereby producing a strong collection surface.
Heating
The members to be bonded are brought to a temperature higher than that at which the filler metal solidifies but lower than the temperature at which the base metals melt. This enables the filler to soften and to wet and also spread along the joint while not impairing the mechanical characteristics of the base substrates.
Cooling
When the filler metal has spread to the required area and the surfaces of the joint members are wetted thoroughly, the assembly is cooled. When the filler metal melts, it evolves and fuses with the other base metals to maximum strength.
People often use brazing and welding interchangeably, but while brazing the filler metals warp but the base metals do not melt as in the case of welding.
Types of Brazing
There are several methods of brazing, each suited to specific applications and environments:
Torch Brazing
This is the most popular technique, here a flame from a gas and torch is utilized to heat the area and to melt the filler material. Torch brazing is small in scale or manually operated.
Furnace Brazing
Here in this method, after loading the complete construction of the parts they are warmed inside the furnace to the desired temperature. It is a suitable process for high throughput and heats evenly through the part for assembly shapes.
Induction Brazing
Induction brazing only requires the passage of electric current through the part to be brazed and the use of a filler metal. This technique allows localized heating and it is equally very effective in application areas where detailed control of the heating process is paramount.
Dip Brazing
Seamlessly huge sections are placed in a bath of molten filler metal, in order that the filler can permeate into the joints. Dip brazing is used mainly for the aluminum parts and is characterized by the relative uniformity of heat supply.
Vacuum Brazing
They are done in a vacuum to minimize the chance of oxidation of the metals since there is no oxygen. This method is normally required for high strength and for those parts that are sensitive to heat.
Benefits of Brazing
Brazing offers several advantages over other metal-joining processes, including:
Strong and Durable Joints
In joints made by brazing, the bonding strength is usually greater than that of the substrates and therefore brazing is appropriate for applications that call for high strength and high durability.
Versatility
Brazing makes it becomes possible to join various types of metal including dissimilar metals like copper to steel and aluminum to stainless steel which is way difficult when using joining processes such as welding.
Low Heat Application
Because the base metals do not melt during the brazing process, it consumes less heat than welding to avoid warping or distortion of steel parts particularly those of thin structure.
Precise Control
Since the joining process is closely controlled, brazing is ideal for complex or limited-geometry connection applications.
Clean and Aesthetic Joints
Brazing can result in smooth and fine fillet without any grinding or polishing which makes the product range very suitable for visible or decorative welds.
Applications of Brazing
Brazing is used in various industries and for a wide range of applications, including:
HVAC Systems: Heating, ventilation, and air conditioning systems use a brazing techniques to join copper as well as aluminum.
Automotive Industry: It is used in creating joints in radiators, fuel pipes and exhaust systems.
Aerospace: Other uses of brazing are in aerospace, where strong joints for important structures in aircraft and space ships are produced.
Plumbing: The process is used where copper pipes and fitting are used in plumbing systems.
Electronics: Main application of brazing is in the fabrication of electrical contacts and circuits used in circuit boards.
Attending Frequently Asked Questions (FAQs)
1. What materials can be brazed?
Brazing is good for joining all copper, steel, aluminum, brass, silver, and even dissimilar metals such as copper to steel and aluminum to food grade stainless steel.
2. What is the difference between brazing and welding?
In brazing, the filler metal is only liquidated while the base metal maintain the solidified state. In welding, both filler and base metals are meant to melt and join or weld together to form the joint. Brazing also require less heat than welding, the risk of distorting the pieces is also less.
3. What is the brazing filler metal and what is its melting point?
In brazing the filler metals that are employed have a relatively low range of melting point that ranges between 450 and 1000 °C / 842 to 1832°F.
4. Has brazing been found useful in high temperature operations?
Yes, brazed joints can take a good deal of heat but this depends on the filler metal used. For harsh service conditions, high-temperature brazing filler materials may be made from nickel or cobalt base materials.
5. Can brazing be used in high volume production?
Yes, brazing is very commonly used in mass production, using techniques, such as furnace brazing that enables the production of leveraging of numerous components in the process.