With today’s manufacturing processes, you can expect highly
uniform consistency within a production lot, and from lot-to-lot.
To take full advantage of these characteristics, a few simple
guidelines should be considered for the continued long-term
mechanical effectiveness of your final assembly.
Material Selection
- environmental strengths, limitations
- static or dynamic sealing
Attachment
- groove fit, adhesive, hardware mounting
- compression fit
Cross section profile
- gap sealing (min/max compression) depending on material
selected
sponges, foam, hollow shapes @ 10%-30%
dense solid shapes @ 2%-30%
- shape
exterior perimeter
interior solid or hollow
Compression force
- closing force
durometer low or high (see below)
solid vs. sponge or foam
hollow interior to lessen force
static or dynamic pressure
- trade offs
sponges have low closure force; and, dense shapes have higher
sealing capability
Compression set
- allowable percentage of height relaxation
- recovery rate from compressed state to relaxed height
Other
- abrasion resistance
- color matching
- secondary finishing - holes, notches, die-cutting, etc.
Durometer
Durometer is the international standard for measuring the
hardness of rubber, sponge rubber, plastic and other nonmetallic
materials. An indenter probe is pressed into the material
and a graduated scale reads the measurement. The harder the
material, the greater the reading. Hardened steel is 100 on
the scale; most common silicones are between 30 and 70. Different
scales allow finer graduated differentiation within the Shore
measurement system.
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