Necking
An informal (slang) term for seal cross-sectional reduction
Nest Plate
A retainer plate with a depressed area for cavity blocks
Nominal Dimension
The mean dimension of a molded article, from which small dimensional (plus and minus) deviations are allowed as manufacturing tolerances
Non-fill
An unintentional void or absence of material in the rubber structure of a part
Nozzle
The hollow cored metal nose screwed into the extrusion end of the heating cylinder of an injection machine or a transfer chamber where there is a separate structure. A nozzle is designed to form a seal under pressure between the heating cylinder or the transfer chamber and the mold. The front end of nozzle may be either flat or spherical in shape
O-Ring
A doughnut-shaped object, or torus, that functions as a seal, blocking the passage of liquids or gases, by being compressed between the two mating surfaces comprising the walls of the cavity (gland) into which the ring is installed
Off register
Eccentric O-ring cross-sectional radii caused by lateral shift of one mold cavity relative to the other
Oil Resistant
Ability of vulcanized rubber to resist swelling and other detrimental effects of exposure to various oils
Orange Peel
A surface finish on a molded part that is rough and splotchy. Usually caused by moisture in the mold cavity
Oscillating Seal
Most commonly used in faucet valves, in this application the inner or outer member of the gland moves in an arc around the axis of a shaft. Movement is limited to a few turns in one direction and a few turns in the return direction (i.e. faucet on, faucet off)
Outgassing
Primarily occurring in vacuum situations, the volatile (evaporative) components of some rubber compounds may become vaporized in the vacuum and released (outgassed) by the compound into the surrounding environment
Overflow
A designed escape reservoir for rubber compound used to insure mold cavity fill and also allowance for excess compound
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