| Once a Week |
Inspect brushes for wear. Replace short brushes, fitting them to commutator contour. |
| Observe commutator color. Properly run welders have a commutator color somewhere between straw and deep brown. Look for bluish or reddish tinges. These indicate overheating. Smooth rough commutator with No. 00 sandpaper. |
Check brush springs to see that they cause uniform contact pressure on commutator. Unequal pressures cause nonuniform current distribution. Adjust brush holder so its face is about 1/4 in from commutator. |
| Be sure to replace worn brushes. If you do not, there is a good possibility that commutator may be/damaged. Check to see that new brushes are of the same grade as recommended by welder manufacturer. Always replace brush in same holder in the same position after inspection. |
| After checking that brushes are satisfactory, blowout machine with a low pressure air hose. Be sure air is dry or it may damage motor and generator. If there are any metal chips in motor or generator windings, or on machine, use the lowest pressure possible to move them out of the machine. |
| Lubricate bearings and other running parts that need oil or grease. Check electrode holders, welding cables and ground connections. Be sure welder is properly grounded or you may run into trouble. |
| Once a Month |
Check commutator color and wear. If badly worn, it may be necessary to turn commutator down on a lathe. Regroove insulation between commutator bars before putting unit back into service. |
| Check bearing temperature while welder is
running. If bearing is overheated, take it apart and make needed repairs. |
| Measure cable circuit length. Total length of both electrode and ground cables should not exceed values given in Table II. It is important to measure cable length on welders because this may be changed by machine operator for different jobs. Cable size and length affect both weld position and efficiency. |
| Check brushes and brush springs. Replace defective parts, following the recommendations given above. |
| Once a Year |
Arc welders need a complete overhaul if they are the mg type. Include in this overhaul complete disassembly of motor (m) and generator (g). |
| Blowout generator armature and field coils and all motor coils. Wash rotor and stator coils with carbon tet and dry completely. Then paint with a good grade of insulating varnish. Repair any defective windings after cleaning and before varnishing. |
| Inspect all electrical connections for corrosion and defects. Tighten loose connections, replace defective wiring, insulation and connections.
Check all controls, adjusting or replacing as necessary. |
| Most m-g arc welders today have grease lubricated ball bearings. These bearings need repacking only once a year. Some machines
have "lifetime" bearings that need lubrication only after several years' service. |
| No matter what type of ball bearing your machine has, keep its parts absolutely clean at all times. Dust or dirt can cause excessive friction that materially shortens bearing life. Never add too much grease to the bearing. Excessive grease increases friction in moving parts of the bearing. |
