NPK M20C, Instruction Manual, Page: 75 / 152

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GENERAL MAINTENANCE
BUILD-UP OF THE PIERCING TIP
Before beginning the build-up of the existing piercing tip, it is necessary to first grind off
all remaining hardface material. After determining the amount of build-up required,
preheat the tip and surrounding area to 300° - 400°F (150° - 200°C) . Using a suitable
underlay rod, build up the areas in question by using stringer welds. Peen after each
pass. Continue to build the areas by overlaying weld stringers. Stop periodically and
cycle the piercing tip through the female jaw tunnel to check the amount of build-up that
is still required. Maintain preheat of the jaw area.
After build-up is complete, it may be required to hardface the piercing tip. Hardfacing
will help prolong the life of the tip and increase the amount of time a tip can be used
before maintenance is once again required. See
“JAW AND TOOTH REBUILD
PROCEDURE”
and follow the same directions.
REPLACING THE PIERCING TIP
To install a new tip, carbon arc (t12) or torch cut (t13) off the old tip approximately the
dimension of your model piercing tip, please note that a seat for the top is present in
the male jaw, see Fig. A. The surface must be prepared by chamfering the male jaw,
see Fig. B. NOTE: Be sure the area is free from all carbon residue, leaving it flat and
smooth.
Fig. A Fig. B