AWS C3.5:2016 pdf download.Specification for Induction Brazing
5.1 Process Description. In induction brazing, the joint area is heated directly or indirectly (using susceptors) by the electromagnetic field set up around a copper conductor through which an alternating electric current is passed. Induction brazing is capable of rapidly heating localized joint areas to the brazing temperature. Typically in induction brazing only the surface of the joint and a minor penetration into the material is directly heated by the induction field. The amount of penetration is controlled by the frequency of the induction coil. The remainder of the joint is then heated by conduction of heat from the surface inwards.
5.2 Equipment
5.2.1 Coils. Coils shall be designed and constructed to be suitable for the particular part configurations to be joined and to be compatible with the induction generator and output transformer used. In most cases, their design should be such as to concentrate the heat at the joint area without unnecessary heating of adjacent areas. Coil design shall take into account any important configuration considerations such as corners or irregular shapes so the heating of the entire joint area shall be in accordance with the brazing procedure specification (BPS). Coil design should take into account, among other parameters, coil size, turm spacing, number of turns, distance to work surface, and conductor diameter. The coil used shall be identified on the BPS.
5.2.2 Induction Power Supply. Induction power supply and associated equipment shall be in good operating condition and suitable for the particular application in both output frequency and capacity. They shall have suitable controls to produce repeatable, controlled heating of the components being brazed.
5.2.3 Induction Brazing Workstations. Induction brazing workstations shall be suitable for the intended purpose and in good condition and working order. They shall be constructed to ensure that the dimensional relationships between the coil, the temperature sensing equipment, and the assemblies are maintained during brazing and not changed by the normal use of the workstation such as the bumping that may occur during loading and unloading of assemblies and brazements. Workstations shall also be designed of materials that avoid unintended coupling with the coil's induction field that could affect coil performance and create a safety issue for the operator.
5.2.4 Temperature Sensing and Control Devices. If used, temperature sensing and control devices shall be in good working order and suitable for the particular application. Automatic systems used for the brazing of Class A and Class B joints shall be calibrated by the use of a simulated assembly with suitable optical instrumentation or thermocouples properly attached so as to accurately read the temperature of the base metal at the joint area to verify control standard settings. Improperly attached thermocouples may be heated independently by the induction heating field or may not accurately read the temperature of the base metal.AWS C3.5 pdf download.