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 Dia•Com
has capabilities to bond metal or plastics to diaphragms
during the molding process. Mechanical bonding is generally
the least expensive and simplest method to achieve. This
process is accomplished by designing the insert with projections
or holes. During the molding process the insert becomes
totally or partially encapsulated by the elastomer creating
a strong mechanical interlock. Figure 1 illustrates a
mechanical bond.
Chemical or adhesive bonding utilizes a commercial adhesive
applied to the non-elastomeric component. The component
is then attached to the elastomer during or after vulcanization
depending on the type of bond required and geometry of
the diaphragm. Figure 2 illustrates an adhesive bond.
When designing the metal insert, it is recommended to
avoid sharp projections extending into the elastomer or
sharp corners at the junction line between the two materials.
Steel is the most prevalent insert material used, but
brass, stainless steel, aluminum, and nylon are also used.
Certain elastomers and insert materials can also develop
a cohesive bond through molecular attraction. This is
most commonly accomplished with the use of brass and sulfur-cured
nitrile.
By bonding inserts to diaphragms, costly assembly operations
can be reduced or eliminated. Additionally, rivet, screw
or other fastening methods which might create leakpaths
through the diaphragm would be eliminated with a bonded
insert.
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