Welding that's well done
Proper operation and maintenance practices makes it happen
by Robert Kotynski
Modern welding systems vary from simple electrode welders to complex multiple-production welders. Regardless of the type of system used, operators must follow proper operating and maintenance practices to achieve production goals, quality and efficiency.
Trouble-free operation of welding equipment results in higher profits.
Maintaining a welding operation over the long term involves keeping the machinery clean, properly ventilated and cooled. The machine should also be kept in an abuse-free operating environment. All equipment operation must be in compliance with the manufacturer's specifications and recommendations. If questions about a particular application arise, the manufacturer should be contacted.
Large volumes of air pulled through the fans of the welding machine keep it cool. Dirt, grease, contaminants and dust can clog and block air passages, which causes the coils to overheat, raises resistance in the coils and reduces conductivity.
Blocked and clogged air passages can result in burned-out coils and decreased efficiency. When coils overheat, their insulation dries out and becomes brittle, resulting in damage.
Regular machine cleaning is critical to maintaining the desired production time. The machine should be blown out once a week with low pressure (not more than 30 psi). This schedule is adequate for normal operating conditions in which airborne contaminants are not a problem.
Take care not to damage the windings by using a higher-pressure air or air that is not clean and dry.
In contaminated environments where high-abrasive or dust-laden air is present, use an industrial vacuum to remove contaminants that can blow into the machine's components. When the contamination level is high, increase cleaning frequency to two or three times per week.
If abrasives are present in the air, commutators become pitted and brushes wear prematurely. For this reason, it is sometimes necessary to add a filtering system to eliminate the abrasive contaminants.
Another contributor to machine uptime is an aggressive training program that educates employees about machine misuse. When properly instituted and maintained, such a program can help to ensure that abuse does not occur.
Abuse and misuse of welding equipment accounts for about 50 percent of maintenance problems. Common misuses to address in training include the following:
1) Ensure proper grounding and avoid a dead short caused by grounding the electrode to the work.
2) Operate equipment only after performing scheduled preventive maintenance and regular maintenance. Never operate equipment that is damaged, unsafe or hasn't been properly maintained.
3) Follow all OEM instructions. Never remove covers (this alters ventilation flow and exposes hazards), block vents, modify controls, or in any way change the manufacturer's intended use or application without first contacting the engineering department.
4) Use the equipment only for its intended purpose. If the equipment is used for work for which it was not designed, including operating it as a power source for functions other than welding, damage can occur.
5) Treat the machine with respect. A little hit with a hammer may fix the air compressor at home, but welding equipment is precise machinery. Any type of shock, dropping or bumping can cause severe damage to the balanced, delicate workings of the system.
Given today's advanced programmable logic controllers and computer-driven machinery, electric shocks or physical disturbances can damage mechanical elements and electrical components.
Good maintenance habits are especially important on more advanced welding systems that use robotics and automation. Proper upkeep includes an appropriately administered preventive maintenance program.
Begin preventive maintenance by compiling a complete equipment list and an inspection schedule. Catalogue all maintenance performed and chart based on inspection analysis. As maintenance is performed, a thorough record and history of inspections, analysis and repairs can be created. This record enables recurring problems and potential machine abuse to be discovered.
Along with preventive maintenance, a maintenance schedule should include clearly defined areas of inspection and procedures. Critical areas include:
3) Fasteners, brackets and bolts
6) Brushes and holders
7) Controls, programmable logic controllers and master panels
8) Motor stators
9) Generator frame
12) Exciter generator
13) Engine (on gas-driven units)
14) Manipulators, feed rolls and positioners
15) Cords, cables, nozzles and guns
Any piece of welding machinery run on a daily basis will eventually require a complete rebuild. Downtime caused by problems or repairs is usually a sign that an overhaul is needed. A yearly or biyearly factory overhaul is important to maintain high-use equipment.
Justification for rebuilding is simple if downtime, repairs or poor-quality welds are frequent. Always justify rebuilding costs after considering the replacement cost of equipment, lost production, subcontracting costs and lost orders.
Robert Kotynski is president of United Machine Corp., a machine service center that specializes in building and rebuilding metal forming equipment.
This article appeared in the April/May 1999 issue of MRO Today magazine. Copyright, 1999.