When manufacturers need a method for joining metals that is fast, precise, and repeatable, they turn to induction brazing to solve these challenges. Induction brazing makes it possible to reduce the size of assemblies and deliver tighter tolerances, while precisely directing heat only where it’s needed.
As a leader in metallurgical innovation, VPE is deeply familiar with the benefits of induction brazing, having manufactured over one-million assemblies using this technique. We help each of our clients achieve precise and efficient bonding of metals using induction brazing techniques ideal for numerous applications and markets.
But what are the advantages of induction brazing that make it such an effective choice for joining metals in so many industries?
Below, we break down the induction brazing process and highlight the advantages of induction brazing that make it a consistent, reliable option for precision joining.
What is Induction Brazing?
Induction brazing is a method for joining two metals using magnetic flux to heat work pieces from within. The induction brazing process raises the temperature just hot enough to melt a braze alloy, but not the bonding materials.
To accomplish this, electricity is run through a copper coil that surrounds the work piece. This generates a magnetic field that couples with the part, quickly heating the work piece from the inside out and melting the braze alloy.
Depending on the application the process may employ a flux. However, for all of our semiconductor equipment, high purity gas transport, 60-year life requirements, and hermetic assemblies a flux is not used.
The induction brazing process is very repeatable, allowing for quick change over between work pieces, making it well-suited for mass production.
Induction brazing is effective with a wide range of metal pairings, including:
- Copper-to-copper
- Aluminum-to-aluminum
- Copper-to-aluminum
- Brass-to-copper
- Stainless steel-to-copper
- Nickel alloys-to-stainless steel
- Kovar-to-molybdenum
- Steel-to-steel
The Advantages of Induction Brazing
Various brazing methods are used for particular applications, but there are several specific advantages of induction brazing that make it ideal for joining metals in small parts, thin-wall tubes, and other specialized assemblies.
Some of the biggest advantages of induction brazing include:
1. Shorter Thermal Cycles
Induction brazing offers a far shorter thermal cycle than other brazing methods, like flame or furnace brazing. The electromagnetic induction used is capable of heating small parts within seconds or minutes, where other brazing methods can take hours to heat up. Shorter thermal cycles allow for more parts to be processed in the same amount of time, while reducing the thermal stress placed on the assembly.
2. Precision Heating
Precision heating in induction brazing is another major advantage of the process. Other brazing techniques require the entire assembly to be heated, but induction brazing is capable of heating only specific zones of a work piece. This is particularly important in thin tubes, multi-material joints, and high-tolerance assemblies. Localizing the heat to a specific area keeps sensitive components from deforming or being damaged during the heating process.
3. Compatibility With a Variety of Materials
Induction brazing can be used with many different types of alloys commonly used in aerospace, HVAC, medical, and industrial applications. The ability to target heat is particularly valuable in induction brazing for aluminum and steel because both materials require controlled heat to avoid distortion. In many applications, it is important to limit the joint time-at-temperature to assure that brittle intermetallics are not formed, especially in hermetic or assemblies subjected to high stresses.
4. Smaller, More Efficient Equipment
Induction brazing equipment is much smaller than a vacuum brazing furnace, requiring less of a footprint. Work pieces only need to be placed properly within the coil, and the coils built for induction brazing applications are generally compact. Maintenance is also minimal compared to vacuum furnaces, and the overall process requires less energy consumption than other brazing techniques.
5. Easier Operation
Other methods of brazing, such as torch brazing and vacuum brazing, require highly trained operators. Once the induction coil and parts have been designed, conducting induction brazing is a much simpler process, only requiring the operator to position the pieces properly, apply filler, and control the electrical input, which itself is often automated.
6. Greater Safety Than Other Brazing Methods
Induction brazing is smokeless, flameless, and quiet. Its ability to localize heat makes it much safer to operate than torch brazing, and minimizes the regulatory and safety risks associated with other brazing techniques that require an open flame.
7. Repeatable, High-Quality Joints
Induction brazing requires a specially designed coil to accommodate specific parts. But once the coil has been produced and the process parameters established, the process becomes highly repeatable. Induction brazing can accommodate everything from small batches, to large orders, while data gathered over many iterations can be used for brazing process improvement.
8. Flexible Design for Complex Geometries
Because coils are designed for each specific application, they can be designed to fit around virtually any shape, including those with complex geometries. This is a key benefit of induction brazing, making it ideal for assemblies with tight access and irregular shapes that would be nearly impossible to heat using other techniques.
Induction Brazing Applications
Induction brazing applications are common in industries where precision, repeatability, and flexibility are sought after. The benefits of induction brazing are particularly of value in smaller parts, and those with complex geometries.
Aerospace
Using induction brazing, VPE produces an average of 10,000 high temperature sensors per month for commercial aviation and defense turbine engines. Other small, complex assemblies used in semiconductor, photonics, and aerospace benefit from the precision of induction brazing, though larger aerospace applications may require other brazing techniques.
Medical Instrumentation
Surgical tools, delicate tube assemblies, and miniature sensors used in medical instruments all benefit from the precision of induction brazing. But it’s the rapid heating cycles and precision application of heat in induction brazing that makes the process especially valuable for heat-sensitive parts commonly used in medical instrumentation.
Automotive
While VPE performs limited induction brazing for automotive applications, the auto industry widely uses induction brazing to build parts and components like tube joints, heat exchangers, and powertrain components.
General Industrial Applications
Many other general industrial applications that seek strong bonds use induction brazing, such as tubular joints, pumps and valves, and custom metal assemblies.
The Induction Brazing Process
The Induction brazing process follows these general steps:
- Coil Design: Designing the right coil for the part you want to braze is the crucial first step. Coils can be designed to fit parts with complex geometries, and can concentrate heat precisely into the joint location.
- Setup and Alignment: The finished coil design is fabricated and connected to the induction machine, which creates a part-specific electrical current. Parts must be aligned, either by moving the part into the coil, or moving the coil around the part. This can be automated, or manually performed by the operator depending on the specific design.
- Heating Cycle: Some designs have an automatic heating cycle, others require the operator to apply electrical current via a foot pedal. This generates the magnetic field within the coil, applying heat directly within the metal, quickly raising the joint to brazing temperature. This is accomplished extremely fast, preventing the part from being exposed to prolonged heating.
- Brazing and Filler Flow: When the joint reaches the brazing temperature, the braze alloy melts and flows through the joint, joining the two metals together with an extremely durable bond.
- Cooling: Once the electrical current is removed, cooling begins immediately. Small parts cool very rapidly, while larger assemblies require more time, but still cool relatively fast. Some projects may require a flowing inert gas to create a protective environment around the assembly, which protects the joint from oxidation during the cool down period.
- Inspection and Testing: Testing is performed based on customer requirements. Some applications, such as medical devices, may require a leak check. Others may require a sample to be tested for every 1 out of 100 assemblies produced.
VPE: Your Experienced Partner for Induction Brazing Applications
Induction brazing offers significant advantages for joining parts with speed and precision heating for small and mid-sized assemblies. Induction brazing is compatible with many different types of alloys, requires significantly less power than other brazing techniques, is considered safer, and does not require extensive training for operators.
The advantages of induction brazing make it an efficient and well-rounded choice for applications in a wide variety of industries including aerospace, medical, electrical, and general industrial usage.
With more than 25 years of experience in induction brazing applications, VPE has the technical expertise and the industrial capabilities to bring success to your next project requiring induction brazing.
We have recently added new induction brazing stations, allowing us to produce large quantities of precision assemblies, such as gas transport manifolds, robust hermetic seals, and pump-out assemblies, and are ready to deliver a fast turnaround on your next project.
We also hold NADCAP certification, which signifies to clients in the aerospace and defense industries that our brazing process meets rigorous industry standards for quality and process control.
Ready to explore the advantages of induction brazing?
Let VPE’s experienced team show you how the precise, repeatable, adaptable nature of induction brazing can benefit your next project.
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