AWS J1.2M/J1.2:2016 pdf free download

AWS J1.2M/J1.2:2016 pdf free download.Guide to Installation and Maintenance of Resistance Welding Machines.
5.2 Electrodes. The high current generated in the welding machine secondary is concentrated at the contact area of the welding electrodes. Mechanical force is applied to the electrode to reduce the electrical resistance of the electrode to workpiece interface, bring the workpiece(s) together, and resist the hydraulic pressure of molten metal at the faying surface. Therefore, the electrodes must have good electrical contact and thermal conductivity as well as being able to withstand high force. The force applied to the electrodes is to be used for welding only and not as a means of reforming the workpieces since this will increase the mechanical wear of the electrodes and the unpredictable electrode force will result in unpredictable weld quality.
Electrodes do wear, pick up foreign matter at the contact surfaces, and pit. The electrodes should be replaced or machined to restore the weld face (i.e., ‘dressed”) dictated by the process or procedure. Replacement may. for example. be required at specilic intervals or when the resistance welding control signals it is no longer able to compensate for electrode condition. This maintenance of the electrodes helps to ensure weld quality, and extends the useful life of the electrode. Machining of the electrode may be accomplished within the machine using a manual or automatic tip dresser, or with proper machining practices outside of the machine, lithe machine is configured for tip dressing. it will likely have a mode which puts the resistance welding control in no weld mode and reduces the electrode force to a level compatible with the tip dress tool. A file is not recommended for dressing electrodes since the resulting electrode welding face will normally be left rough and have improper contact area,
Proper cooling of the electrodes is very iniportant (see “Cooling System”). Cooling water should pass as close as possible to the weld contact point as is practical. Blind shanks are not recommended since water should have intimate contact with the cap. The flow of water to the spot welding electrode must enter through the water deflection tube and leave along the inner walls of the electrode, as shown in Figure 1. The angled end of the water deflector tube should be inserted to extend to3 mm (1/8 ml from the end of the water hole in the electrode; this reduces the chance of steam pockets occurring during welding. Improper cooling will tend to soften the electrode material and reduce electrode life, resulting in increased costs for electrode replacement, lost production, and maintenance.
Water leaks around the seat of spot welding electrodes may occur. These leaks should never be stopped with paper. thread seal tape, or other insulating materials. Leaks of this nature can be stopped by removing the electrode so the taper can be cleaned or any small burrs, nicks, or scratches removed. If that fails, it is sometimes possible to address with the application of a small amount of special current-carrying grease to the contact surfaces between the electrode and its holder.AWS J1.2M/J1.2:2016 pdf free download.