METAL DISINTEGRATORS
Sometimes you cannot remove a broken tap or stud
with the usual methods we explained earlier in this
chapter. In those cases, you may use a metal
disintegrator to remove such a piece without damaging
the part. This machine uses an electrically charged
electrode that vibrates as it is fed into the work and
disintegrates a hole through the broken tap or stud. The
part to be disintegrated and the mating part that it is
screwed into must be made from a material that will
being used to remove a broken stud.
You can find the specific operating procedure for
the metal disintegrator in the operators material
furnished by the manufacturer. However, we will
explain several steps in the setup for a disintegrating job
that are common to most of the models of disintegrators
found aboard Navy ships.
First set up the part to be disintegrated. Some
disintegrator models have a built-in table with the
disintegrating head mounted above it much like a drill
press. On a machine such as this, you need only bolt the
part securely to the table and be sure the part makes
good contact to provide an electrical ground. Align the
Figure 13-24.--Gate valve reseater.
tap or stud to be removed square with the table so the
electrode will follow the center of the hole correctly. If
there is misalignment, the electrode may leave the tap
disintegrating head vibrating and a selector switch for
or stud and damage the part. Use either a machinist's
the heat or power setting. The position of this switch
square laid on the table or a dial indicator mounted on
depends on the diameter of the electrode being used.
the disintegrating head to help align the part. If the part
Some models have an automatic feed control that
will not make an electrical ground to the table, or if the
regulates the speed that the electrode penetrates the part
model of machine you are using is designed as an
to be removed. Regardless of whether the feed is
attachment to be mounted in a drill press spindle, attach
automatic or manual, do NOT advance so fast that it
the disintegrator's auxiliary ground cable to the part.
stops the disintegrating head and the electrode from
The diameter and length of the part to be removed
vibrating. If this happens, the disintegrating action will
determines the selection of the electrode. As a general
stop and the electrode can be bent or broken.
rule, the electrode should be large enough in diameter
to equal the smallest diameter of a tap (the distance
between the bottom of opposite flutes). If you plan to
IN PLACE MACHINING
remove a stud, the electrode must not be so large that a
slight misalignment can cause it to burn or damage the
There are times when a job cannot be brought to the
part. Use a scribe and a small magnet to remove any of
shop and the MR must go and do the job in place. Some
the stud material not disintegrated.
examples of in-place machining include the repair of
A free-flowing supply of clean coolant is an
globe and gate valves, the resurfacing of pipe and valve
essential part of the disintegrating operation. The
flanges, boring valve inlay areas, and general machine
coolant is pumped from a sump to the disintegrating
work.
head and then through the electrode, which is hollow,
to the exact point of the disintegrating action.
There are a number of machines you can use on
these jobs. For example, you can use the gate valve
Different machines have different controls that you
must set. However, most have a control to start the
13-19