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TM 750-245-4
CHAPTER 9
ADHESIVE BONDING, POTTING, EMBEDDING, AND SEALING
Section I. INTRODUCTION
adhesives; usually the only difference is in the amount
9-1. General
of material used. Adhesive processes require very
WARNING
small amounts of material as compared to potting
Many of the chemicals used in
processes. Potting compounds are those resins which
adhesive technology are toxic and
can be converted from liquid to solid state at room or
present safety hazards to personnel.
slightly elevated temperatures and at atmospheric
Ovens are often used to heat
pressure. Potting compounds are used to protect, hold
material. They should always be well
in place, and insulate mechanical and electrical parts.
ventilated to prevent inhaling of
Potting, embedding, and sealing compounds may be
chemical fumes. The surrounding
broken into three general categories:
working area should be free of
(1) Polyurethanes, epoxies, silicones, and
contamination of materials as they
polysulfides
are skin irritants. Have fire fighting
(2) Sealants
containing
solvents
and
equipment nearby in case of
elastomers
emergencies as some chemicals are
(3) Staking sealants (Loctite)
highly flammable. Protect the eyes
from exposure. Always have first aid
c. Unless otherwise stated, assume that all
information applies to sealants as well as to potting and
equipment nearby.
embedding compounds. Applied potting compounds are
relatively difficult to repair; be careful when using these
a. This chapter describes adhesive bonding,
materials on expensive parts.
potting, embedding, and sealing operations employed in
the maintenance of materiel.
9-2. Definitions, Abbreviations, and Terms
b. In many cases, potting, embedding, and sealing
The inspector should refer to appendix B for the
compounds are identical to compounds used as
definitions, abbreviations, and terms applicable to
adhesive bonding, potting, embedding, and sealing.
Section II. ADHESIVE BONDING
9-3. General
9-5. Cleaning Parts
The use of adhesive bonding agents involves five
a. To achieve maximum adhesion, the adherent
phases: selection of the proper adhesive, cleaning,
surface must be carefully prepared. Clean all potting
application, curing, and inspection of the finished joint.
areas until they are free from oil, grease, release
It is assumed that the bonding will normally consist of
agents, rust, moisture, or fingerprints. Skin grease or
repair of an existing joint and does not involve the
perspiration deposited on the adhesion surface may
design of a new joint.
reduce adhesion by as much as 75 percent. Basically,
four methods are utilized, which are brushing, flowing,
9-4. Types of Adhesives
spraying, and rolling.
The broad use of adhesive bonding has resulted in
b. Thoroughly
clean
the
surface
either
development of many different types of adhesives.
mechanically or chemically, depending upon the type of
Therefore, no discussion will be made here of the
material and the contaminant to be removed. To
various types. The system technical manuals should be
eliminate dirt, scale, rust, and similar contaminants, use
followed in selecting the proper adhesive, determining
wire brushing, buffing with powdered wire brushes,
the mixture, and selecting the cure time and
sandpapering, sandblasting, or other types of abrasion.
temperature.
Degrease by solvent cleaning before and after abrading
9-1
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