How it works, why it's better, and where ENRX leads the way
Induction brazing is one of the most precise, efficient and reliable methods for joining metals in industrial manufacturing. Compared to traditional flame brazing, it delivers faster cycle times, more consistent joint quality and a safer working environment – all without contact between the heat source and the base metal.
Key takeaways
- Induction brazing generates heat within the base metal itself, producing faster, cleaner and more consistent joints than flame brazing – without contact between the heat source and the workpiece.
- Gap control is critical: the optimum clearance for most silver-content alloys is 0.05–0.1 mm, and must be calculated at brazing temperature, not room temperature.
- Induction's controllability makes the brazing process visible and measurable, reducing overheating, oxidation and the need for secondary finishing.
- Aluminium brazing demands specialist expertise: the margin between brazing temperature and melting point can be as little as 20–50°C.
- Controlled atmosphere brazing eliminates flux entirely, making it the preferred method for mission-critical components in aerospace, medical and power generation.
- The induction coil is as important as the power source – a poorly designed coil undermines the entire system.
What is induction brazing?
Brazing is a metal-joining process that uses a filler metal – an alloy with a lower melting point than the base materials – to bond two or more closely fitted metal pieces. When the filler melts, it is drawn into the narrow gap between the parts by capillary action, interacting with a thin layer of each base metal to create a joint that is strong, leak-proof and usually requires no secondary finishing.
What sets induction brazing apart is how the heat is generated. Rather than applying an external flame or placing parts in a furnace, induction brazing uses an electromagnetic field created by alternating current flowing through a copper coil. This field induces eddy currents directly within the base metal, generating heat from the inside out. The coil never touches the workpiece. The base metal never touches the heat source.
The result is a process that is not only faster and cleaner than flame brazing, but fundamentally more controllable – and that controllability is what makes the difference in high-volume or high-precision manufacturing.
It is worth distinguishing brazing from two closely related processes:
- Welding melts the base materials themselves to form the joint. Brazing does not – the base metals remain solid throughout.
- Soldering works on the same capillary principle as brazing, but at temperatures below 450°C. Brazing typically operates between 450°C and 1150°C, producing stronger joints suited to more demanding applications.
Induction brazing of heat distributor.
How does the induction brazing process work?
A successful induction braze depends on getting several factors right simultaneously. Here is what the process looks like from start to finish.
1. Joint design and gap control
The gap between the two base metals is one of the most critical variables in brazing. Too small, and the filler alloy cannot spread properly. Too large, and capillary force is lost – the joint becomes a weak alloy bridge rather than a true metallurgical bond.
For most silver-content alloys, the optimum gap is between 0.05 mm and 0.1 mm. But this must be calculated at brazing temperature, not room temperature, because thermal expansion shifts the gap as parts heat up. A brass-to-steel joint, for example, may start as a force fit at room temperature and open to the correct clearance once both metals have expanded to brazing temperature. Getting this right requires specialist knowledge of material properties and the ability to model the joint before production begins.
2. Cleaning and flux application
Base metals must be clean and free of oxides before brazing begins. A flux – typically a solvent paste applied to the joint area – cleans the metal surface, prevents new oxidation during heating and improves filler flow. Applying too little flux is a common mistake: once flux becomes saturated with oxides, it loses its protective ability and joint quality suffers.
In some cases, flux can be eliminated entirely. Phosphorus-bearing filler alloys can braze copper without flux. For mission-critical components in aerospace, medical and power generation applications, controlled atmosphere brazing replaces flux altogether. Parts are brazed inside a sealed chamber or bell jar where the atmosphere is managed with inert gases or vacuum – producing exceptionally clean, high-integrity joints at scale.
3. Coil design and heat induction
The induction coil – or inductor – is the heart of the system. Its geometry determines where heat is deposited in the workpiece, how quickly it reaches brazing temperature and how uniformly that heat is distributed. A well-designed coil delivers precisely defined heat-affected zones, minimising thermal spread to adjacent components and protecting nearby insulation or sensitive materials.
Coil design is a demanding engineering discipline. Cooling water flow rates, magnetic flux concentrators, impedance matching with the power source, insulation selection – all of these must be calculated correctly. A poorly designed coil does not just underperform; it can damage equipment, compromise joint quality and raise long-term production costs. This is why ENRX designs, manufactures and services its own coils in-house, maintaining a global database of every coil ever produced to support rapid replacement and repair.
4. Brazing and post-processing
Once the joint reaches the correct temperature, the filler appears to 'float' on the surface before being drawn evenly into the gap by capillary action. The operator can watch this happen – a significant advantage over flame brazing, where a white-hot flame makes visual monitoring extremely difficult.
After the filler solidifies (typically below 400°C), any remaining flux residue is removed, most commonly by water quenching. Properly brazed joints are clean, neat and dimensionally accurate – usually requiring no further grinding, milling or finishing.
Seven reasons to choose induction over flame brazing
If your operation currently uses flame brazing, the case for switching to induction is compelling. Here are the seven most significant advantages.
1. Speed. Induction transfers more energy per square millimetre than an open flame, achieving brazing temperature faster and allowing more parts to be processed per hour. Short heating cycles also mean less thermal mass to manage, reducing energy consumption per part.
2. Throughput. Because induction systems are compact and easily integrated into production lines, batches no longer need to be taken off-line for brazing. Parts can be brazed in-process, dramatically reducing handling time and work-in-progress inventory.
3. Consistency. Set the parameters once and the system repeats them exactly, cycle after cycle. There is no variability from operator technique, fatigue or environmental conditions. For high-volume production, this consistency translates directly into lower rejection rates and reduced rework costs.
4. Controllability. The brazing process is visible and measurable. Operators can monitor exactly what is happening, adjust in real time and intervene if something looks wrong. Overheating – a common cause of joint failure and base metal damage in flame brazing – is far easier to prevent.
5. Joint quality. Induction's controlled, localised heat minimises distortion and warpage, eliminates the risk of hydrogen embrittlement, and reduces oxidation and scaling on the metal surface. Fewer oxides mean less cleaning, lower consumable costs and cleaner joints.
6. Working environment. Open flames create heat, noise and fumes. Induction is quiet, produces virtually no ambient heat, and makes it easy to extract any fumes from flux or alloy. Operators work more comfortably and safely, with less fatigue over a full shift.
7. Compact footprint. ENRX brazing systems are designed to integrate into existing production cells without significant reconfiguration. Mobile units can be transported between workstations, repair sites or factory locations as needed.
Where is induction brazing used?
Induction brazing is a remarkably versatile process. ENRX systems are used across a wide range of industries and component types – here are the most significant.
Automotive
Electricity generation and distribution
Appliances and HVAC
Aerospace, renewables and beyond
The role of the induction coil
No induction brazing system performs better than its coil. The inductor determines heat distribution, cycle time, energy efficiency and joint consistency. Getting it wrong – using an off-the-shelf or improvised coil for a demanding application – leads to uneven heating, reduced joint quality and premature coil failure.
After-sales support: built for uptime
ENRX offers a full range of after-sales services to keep your system running at peak performance
- Operator training – hands-on programmes that turn your staff into skilled induction brazing practitioners
- Telemetric monitoring – remote oversight of key process parameters, enabling proactive intervention before issues become downtime
- Scheduled preventive maintenance – tailored programmes aligned to your production schedule and equipment profile
- Service level agreements – flexible contracts covering technical support, software upgrades, spare parts at preferential rates and defined on-site response times
- IoT-ready systems – ENRX induction equipment supports remote diagnostics and fine-tuning, improving long-term reliability and reducing the cost of support
With a global network of factories, laboratories, offices and service agents, ENRX has the scale to support customers wherever they operate.
Frequently asked questions about induction brazing
Why ENRX?
With decades of application knowledge, in-house coil engineering, a global service network and a product range that spans from handheld mobile units to multi-megawatt automated production lines, ENRX offers a complete solution, designed, built, installed and supported by the same organisation.
ENRX brazing systems: from mobile units to turnkey machines
ENRX offers three categories of brazing system, covering every point on the spectrum from flexible manual operation to fully automated production.
Minac – mobile induction heating systems
The Minac is ENRX's compact, portable induction converter, available in output powers from 10 to 220 kW. It supports a virtually unlimited range of coil designs and can be transported between workstations, loaded into a vehicle and taken to remote work sites. Power output units are available as handheld 'power pistols' – transformers connected to the Minac by long, flexible cables – making it possible to reach components in tight or awkward positions. Twin versions provide two fully independent power outputs from a single converter.
Sinac – stationary induction heating systems
Where continuous, high-volume production is required, the Sinac range delivers output powers up to 2,000 kW. Available in serial- and parallel-compensated versions, the Sinac features automatic load matching, a constant power factor of 0.95 at all power levels and a diode rectifier optimised for energy efficiency. Twin-output versions are available.
Both the Minac and Sinac are compatible with the ENRX Setpoint Recorder – a 'teach-in' solution that records and replays exact heating patterns, supporting repeatable quality without relying on manual parameter entry.
Customised brazing machines
For applications that require maximum throughput or where the component geometry demands a highly specific approach, ENRX designs and builds turnkey brazing machines. These can include automatic loading and unloading, rotary work tables, multiple brazing heads, controlled atmosphere enclosures, closed-loop cooling systems, advanced PLC control with touchscreen interfaces, and integration with robotic handling systems. Every machine is powered by ENRX heat generators and pre-assembled and tested before delivery.