Page 54 - Handbook of Adhesives and Sealants

22 Chapter One

allurgically incompatible materials, thermoset plastics, ceramics, elas-
tomers, thin materials, or very small parts. Adhesive bonding is also
generally appropriate when there are large areas to join, or when ad-
hesives can be chosen to provide improvement in manufacturing pro-
ductivity.
Usually the decision of which fastening method to use involves sev-
eral trade-offs. A trade-off analysis, as shown in Table 1.6, can be
useful in identifying potential fastening methods. When this is per-
formed, the possibility of using adhesives over other methods becomes
apparent.
The science of adhesive bonding has advanced to a degree where
adhesives must be considered an attractive and practical alternative
to mechanical fastening for many applications. Adhesive bonding pres-
ents several distinct advantages over conventional mechanical meth-
ods of fastening. There are also some disadvantages which may make
adhesive bonding impractical. These pros and cons are summarized in
Table 1.7.
The design engineer must consider and weigh these factors before
deciding on a method of fastening. However, in some applications ad-

TABLE 1.6 How Joining Methods Compare 5
Adhesive
Riveting Welding Brazing bonding
Preliminary machining P E P E
With thin metals P P F E
Limits on metal F P P E
combinations
Surface preparation E G F P
Tooling E F F F
Need for access to joint P P E E
Heat requirements E P P F–G
Stress distribution P F–G E E
Sealing function P F E G
Rate of strength development E E E P
Distortion of assembly F P F E
Final machining G–E F E E
Final heat treatment E F F E
Solvent resistance E E E F
Effect of temperature E E E P
Ease of repair G P P F
Level of skill required E G E E
NOTES: E—Excellent, G—Good, F—Fair, P—Poor.