Dry Abrasive Blasting
Dry abrasive blasting involves propelling abrasive
particles against the metallic surface by either
high-pressure air or spinning paddle wheel. The
striking of these particles against the metal abrades
away deteriorated paint and scale. Many abrasive blast
machines (portable dry-honing machines) reclaim
used grit by cleaning and sifting out dirt, scale, and
damaged grit. (See figure 4-28.) Grit that has been
recycled after use on steel, brass, bronze, or
copper-nickel should not be used on aluminum. Do not
blast aluminum with steel or copper slag or chilled iron
grit. Table 4-3 lists some common abrasive materials
and grit sizes.
CLEANING SURFACES WITH
Power tool cleaning includes devices that impact
the metallic surface with an abrasive substance or
mechanical object. Impact tools, powered wire
brushes, and disk sanders are common power tool
cleaners for SE.
Usually, electric or pneumatic disk sanders abrade
the metal surface of SE with coarse to fine grit. When
used with the needle gun, the disk sander can produce
a uniform anchor pattern of very closely spaced
When using abrasive power hand tools, you
must wear eye protection to prevent serious
Q72. What is the preferred surface preparation
method for many of the components of support
What should you use during the abrasive process
to prevent flash rusting?
CORROSION DAMAGE LIMITS
LEARNING OBJECTIVE: Recognize the
limits in removing corrosion damage.
Impact tools, such as the needle gun (pneumatic
descaler), provide a rapid means for removing rust and
old paint from metal surfaces of SE. These tools must
NEVER be used on aluminum.
A wire brush powered pneumatically or by electric
motor is a method for removing small amounts of paint
and rust from SE. Often, the overextended use of a wire
brush results in a metal surface that is polished to a
glossy appearance. A polished surface produces a poor
anchor pattern for paint bonding.
Corrosion damage limits refer to the amount of
metal that may be removed from a corroded part
without impairing the strength and function of the part.
When removing corrosion, maintenance personnel
must be very careful not to remove more of the metal
than is necessary to ensure complete removal of
corrosion. Figure 4-29 shows the maximum corrosion
depths allowed on the various components of the nose
landing gear. When damage exceeds the limits
specified in the SRM or the corrosion control section
of the MIM, the affected part must be replaced if
structural repair of the damage is not possible.
Table 4-3.Recommended Grit for Steel and Aluminum