Maintaining resistance welding machine

Resistance welding (RW) results are only as good as the machine that is completing the process. By understanding how to properly maintain your resistance welding machine, you will be able to prevent unnecessary problems that tend to plague the unit's critical areas. Since the process of RW is not widely understood, machines themselves are typically understood even less. A crisis often results when RW parts are rejected because of poor weld strength or if the machine quits altogether. Although RW equipment looks deceptively simple and maintenance-free, several systems and components need to undergo maintenance once a year. Quality resistance welds are the result of the machine's electrical, mechanical, pneumatic, and water-cooling systems working together properly. A problem with any one of these systems can mean machine breakdowns or poor-quality welds. Electrical systems RW is a high-speed method of joining metals by using pressure and electric heating under accurate control. The machine applies high forging force, and unlike most arc welding processes, no additional material is added. The machine's transformer converts high incoming voltage and low primary amps into high secondary amps and low secondary volts. As an example, a typical RW transformer might convert 200amps of incoming power into 20,000 secondary amps. At the same time, the transformer converts line voltage, 220V or 440V, into very low secondary voltage, typically less than 10V. That's why you can touch the secondary of an RW machine during the welding process and not get shocked, even though thousands of amps are being produced. However, this also means that the machine's secondary circuit is prone to problems caused by loose connections, oxidation, dirt, grease, and other contamination that can serve as unwanted electrical insulation. As the secondary circuit deteriorates, the output of the machine is reduced. Once deterioration starts, it feeds on itself and accelerates, because of increased resistance and heat. Consider coating the mating surfaces with a layer of cool-amp silver-plating powder, which can be applied by hand and will significantly reduce contact resistance in the joint. Make sure all bolts used in the secondary connections are nonmagnetic, such as brass, and are tightened securely and evenly. Keep pneumatics running smoothly Consistent application of the proper forging force for the material being welded is required for good weld quality. Moisture is the most common problem found in RW pneumatic systems, and compressors connected to air-operated machines should have an air drier installed. Each machine must have an air filter, regulator, and if required a lubricator installed. Preventive maintenance should include looking inside the air cylinder once a year and rebuilding it as required, with new packing and seals. If the cylinder has sat idle with moisture inside for any length of time, cylinder walls and shafts may need to be polished or replaced because of pitting. If the cylinder is not permanently lubricated and a lubricator is installed, be sure that it's set properly, with about one drop of oil per 10 to 15 strokes of the machine. Most lubricators are set too high, resulting in the machine's air exhaust mufflers, clogging with oil and constricting the flow of air exiting the cylinder. In addition to making a mess, this can hinder the proper application of weld force and reduce weld quality. Electric servo-actuated force delivery systems are starting to replace air cylinders on RW machines due to their accuracy and performance. Also, they are more environmentally friendly because they do not emit oil mist.

Although RW equipment looks simple and maintenance-free, several systems and components need to undergo maintenance once a year.

Water cooling and condensation Water cooling is an often-overlooked factorAir Jordan