Induction Brazing - Prestige Thermal

BRAZING

Overview	Brazing and Soldering are ideal applications for the induction heating process. Benefits include the following: Direct, localized heating of only the joint area Minimal heat-affected zone Reduced radiant heat to the environment Uniform heating Enhanced physical appearance High quality, leak proof joint High volume processes Mixed production processes Repeatable Not subject to variation
Using Induction	Modern induction heating provides many advantages over other heating methods and is commonly used for brazing applications. Heating through induction provides reliable, repeatable, non-contact and energy-efficient heat in a minimal amount of time. Solid state systems are capable of heating very small areas within precise production tolerances, without disturbing individual metallurgical characteristics. Induction can be used for either surface or through heating; case brazing is possible depending on time, temperature and the material's characteristics. Closed loop control, through the use of an optical pyrometer or other temperature sensing device, can provide constant heat with a tolerance as low as 3°C at 700°C. Induction heating also ideal for in-line production processes because of its ability to produce repeatable, rapid and accurate heating cycles. Typical power supplies for induction brazing range from 1 to 60kW, depending on the parts and application requirements.

Applications	Brazing Steel Tubes Brazing Steel Regulator Bases for fuel injection system Brazing Thread Ring Gauge Blocks Brazing Wire Brazing of carbide onto wear parts
Setup	Any brazing process consists of two stages. First, the metal part is placed inside an induction coil and power is supplied until the part reaches the correct temperature. The temperature can be checked with an optical pyrometer, temperature sensing paint or some other temperature-sensing device. The second stage is holding or soaking at the correct temperature, which can be accomplished with a closed loop temperature control system.
Materials Needed	Metal to be brazed Temperature Sensing Device The temperature of the metal must be checked with an optical pyrometer, temperature sensing paint or other sensing mechanism. Closed Loop Temperature Control System The control system monitors and constantly adjusts the output of the power supply so as to maintain the correct surface temperature on the part. This allows the core of the part to reach a uniform temperature. A typical system would include the power supply, heat station, coil and an optical pyrometer. Heat source: Fast, precise heating works best.
Common Problems	The proper brazing temperature is determined by the type of material and the amount of heat required; you may need to experiment a bit to find the optimum level. Once the correct parameters have been established, the process can be repeated with accuracy. During booth heating and cooling, temperature gradients exist between the inside and outside sections of the part. If the rate of temperature change is too great, these gradients and internal stresses may lead to warping or even cracking.
Tricks Of The Trade	Time is of the utmost importance. The actual brazing time must be long enough to allow any necessary transformation to take place. Surface oxidation or scaling may be presented or minimized by brazing at a relatively low temperature or in a non-oxidizing atmosphere.