
L/D Ratio:
A term used to help define an injection screw. This is the screw
length-to-diameter ratio.
Manifolds:
distribute melt from the inlet component to one or more
submanifolds within a Hot Runner.
Melt Flow Rate:
A measure of the molten viscosity of a polymer determined
by the weight of polymer extruded through an orifice under specified
conditions of pressure and temperature. Particular conditions are dependent
upon the type of polymer being tested. MFR usually is reported in grams
per 10 minutes. Melt flow rate defines the flow of a polypropylene resin. An
extrusion weight of 2160 grams at 446°F (230°C) is used.
Melt Flow Index:
Term that defines the melt flow rate of a polyethylene resin.
An extrusion weight of 2160 grams at 310°F (190°C) is used.
Mold:
A series of machined steel plates containing cavities into which plastic
resin is injected to form a part.
Mold Frame:
A series of steel plates which contain mold components,
including cavities, cores, runner system, cooling system, ejection system, etc.
Mold-Temperature-Control Unit:
Auxiliary equipment used to control Hot
Runner temperature. Some units can both heat and cool the mold. Others,
called chillers, only cool the mold.
Moving Platen:
The platen of an injection molding machine that is moved by
a hydraulic ram or mechanical toggle.
Multi-Cavity Mold:
A mold having two or more impressions for forming
finished items in one machine cycle.
Multi-Material Molding:
The injection of two-or-more materials, in sequence,
into a single mold during a single molding cycle. The injection molding
machine is equipped with two-or-more plasticators. (See also co-injection)
Nest Plate:
A retainer plate in the mold with a depressed area for cavity
blocks.
Non-Fill:
See short shot.
Non-Return Valve:
Screw tip that allows for material to flow in one direction
and then closes to prevent backflow during injection.
Machine Nozzle:
The hollow-cored, metal nose screwed into the injection
end of a plasticator. The nozzle matches the depression in the mold. This
nozzle allows transfer of the melt from the plasticator to the runner system
and cavities.
Packing:
The filling of the mold cavity or cavities as full as possible without
causing undue stress on the molds or causing flash to appear on the finished
parts. Over- or under-packing results in less than optimum fill.
PET:
Polyethylene Terephthalate, a type of polyester and a leading recyclable
plastic material.
Pinpoint Gate:
A restricted gate of 0.030 in. or less in diameter, this gate is
common on Hot Runner molds.
21-3
GLOSSARY OF TERMS
Hot Runner User Manual
© 2020 Mold-Masters (2007) Limited. All Rights Reserved.
Содержание Hot Runner
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