Page 49 - Handbook of Adhesives and Sealants

An Introduction to Adhesives and Sealants 19

brazing, soldering, and mechanical fastening. All fastening and joining
systems, including adhesives, fall into one of three general categories
illustrated in Fig. 1.5.

Periodic—the attachment of two members by occasionally placing
through hole fasteners or other individual mechanisms. (This is the
most widely used joining technique for structures requiring high
mechanical strength and a minimum of sealing or other non-
strength functions.)
Linear—a continuous or occasional edge bead attachment, such as
welding.
Area—an attachment achieved by full-face contact and union be-
tween the two mating surfaces. (Soldering, brazing, and adhesives
are examples of area attachment.)

Although adhesive bonding can be successfully employed in periodic
or linear attachment applications, the main benefits and advantages
are realized when adhesives are used in the ‘‘area’’ attachment de-
signs.
In evaluating the appropriate joining method for a particular appli-
cation, a number of factors must be considered, such as those sug-
gested in Table 1.5. There generally is no single method of fastening
that is obviously the best choice. Some fastening methods can quickly
be eliminated from consideration, such as the welding of ceramic sub-
strates or the use of an organic adhesive in an application that will
see extremely high service temperatures. Adhesives are usually the
proper choice when the substrates are physically dissimilar or met-

Figure 1.5 Periodic, linear, and area attachment systems. 5