Neck - The part of a container
where the shoulder cross section area decreases to form
the finish.
Neck Bead - A protruding
circle on a container at the point where the neck meets
the finish, the diameter of which usually equals the
outside diameter of the closure.
Neck Insert - Part of the
mold assembly which forms the neck and finish. Sometimes
called Neck Ring.
Nest Plate - A retainer
plate with a depressed area for cavity blocks used in
injection molding.
Nonpolar - Having no concentrations
of electrical charge on a molecular scale, thus, incapable
of significant dielectric loss. Examples among resins
are polystyrene and polyethylene.
Nonrigid Plastic - A non-rigid
plastic is one which has a stiffness or apparent modulus
of elasticity of not over 50,000 psi. at 25 degrees
C when determined according to ASTM test procedure D747-43
T.
Notch Sensitivity - The
extent to which the sensitivity of a material to fracture
is increased by the presence of a surface in homogeneity
such as a face notch, a sudden change in section, a
crack, or a scratch. Low notch sensitivity is usually
associated with ductile materials, and high notch sensitivity
with brittle materials.
Nozzle - The hollow cored
metal nose screwed into the extrusion end of (a) the
heating cylinder of an injection machine or (b) a transfer
chamber where this is a separate structure. A nozzle
is designed to form under pressure a seal between the
heating cylinder or the transfer chamber and the mold.
The front end of a nozzle may be either flat or spherical
in shape.
Nylon - The generic name
for all synthetic fiber-forming polyamides; they can
be formed into monofilaments and yarns characterized
by great toughness, strength and elasticity, high melt
point, and good resistance to water and chemicals. The
material is widely used for bristles in industrial and
domestic brushes, and for many textile applications;
it is also used in injection molding gears, bearings,
combs, etc. |
