Page 79 - Handbook of Adhesives and Sealants

An Introduction to Adhesives and Sealants 47

The joining of surfaces with an adhesive or sealant consists of a
series of individual operations, each of which must be done properly
to achieve the desired result. The number of operations and the
method of actually making the bond will depend on several factors.
The factors that must be considered are the type of materials to be
bonded, the nature of the assembly design, the adhesive to be used,
the facilities available, the time allotted (e.g., number of joints per
minute) and the cost allocated. Details of these production processes
are given in later chapters.
Adhesive bonding is somewhat unique in that there are numerous
processes available. Certain methods even use the substrate itself as
an adhesive. These are known as solvent welding and thermal weld-
ing. Heat or solvent can be applied in some manner to the substrate
to turn part of the material into a liquid. This liquefied material then
acts as the adhesive or sealant, filling in the gap at the joint and
solidifying on cooling from the melt or by loss of solvent. The substrate
in essence becomes the adhesive. These processes will be considered
in this Handbook as a special type of adhesive bonding although they
are popularly referred to as welding methods.
Many of the adhesive or sealant problems that evolve are not due
to a poor choice of material or joint design but are directly related to
faulty production techniques. The user must obtain the proper proc-
essing instructions from the manufacturer and follow them consis-
tently to ensure acceptable results.

1.8 Sources of Information
Information and literature available from the manufacturers of ma-
terials can provide useful assistance regarding specific adhesive or
sealant applications. These manufacturers may be classified as:

Base raw materials suppliers to the adhesives and sealants industry
Formulators or adhesive and sealant suppliers
Manufacturers of raw materials that are used as substrates (i.e.,
aluminum, steel, plastic, composites, etc.)

These manufacturers are usually very happy to provide information
and guidance related to their products. Often, they will offer to the
end-user the utilization of their research and development groups
and/or test laboratories to provide suggestions, develop specific for-
mulations, or look at problems and other issues that may arise. The
use of these resources is highly recommended.
Specifications and standards also provide a significant amount of
information regarding adhesives and sealants. These documents de-