Extraordinary Maintenance; Remedies For Welds Imperfections; Spare Parts - TECNA 7911 Manuel D'instruction

EXTRAORDINARY MAINTENANCE

If the welder overheats, check that the duty cycle is not too high
(table 4), the electrode tip diameter is correct (table 2); on water
cooled models check that water flow is adequate.
Thermostatic protection on all models.
On item 7911 this protection stops the welding process when the
duty cycle is too high. The welder can be used only when tempe-
rature is within the required values.
On items 7913-7915 the thermostatic protection stops the welding
process when the water flow is too low. On these models, the
thermostat does not protect the transformer against working
overloading.
If performances are lower than expected check:
• that, when welding, line voltage drop is lower than 10-15%;
• that the supply cables section is adequate;
• that the electrodes diameter is appropriate for the work to be
carried out;
• on item 7913-7915 that the cooling water flows in the required
quantity.
• that the welding pressure shown on the gauge-pressure is
adequate for the work in process.
• that the gauge-pressure works properly.

REMEDIES FOR WELDS IMPERFECTIONS

This chapter has been introduced in order to facilitate the troubleshooting of the most common imperfections caused by incorrect
adjustment. Notice that each one can be caused by different causes as there are many parameters affecting the welding process. The
following table specifically refers to low carbon steel spot welding, but, with the due consideration, it can also be useful for other
applications.
16
Art. / Item 7911-7913-7915

SPARE PARTS

Look at the exploded views and at the spare parts list at the end of
this instruction manual to identify the code of the required parts.
The first number of the code has the following meaning:
1... standard components widely available from industrial
suppliers (e.g. screws, washers, nuts, etc.).
2... commercial components which, providing that the same
quality parameters are adopted, can be purchased anywhere
(filter lubricator regulator units, thyristors, pressure gauges,
hoses, switches etc.).
3... components manufactured by TECNA
4... components manufactured by TECNA
5... electronic circuits and assemblies manufactured by TECNA.
7... assemblies composed of parts belonging to any or all of the
above codes but which for the sake of simplicity are available
ready-assembled.
All spare parts, standard, commercial or TECNA, are available
from TECNA. When ordering, please, always state: spare parts
code and quantity, voltage and frequency, the serial number and
year of manufacture of the welder they are ordered for. The number
followed by an asterisk warns that you must state both voltage
and frequency.