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Rigid Profile Large Profiles
HIPS Rail
for
Treadmill
Vinyl
Siding
Flat Profiles
Flexible
Profiles Coextrusion
Profile - Rigid
Small Profiles and Flexible
plastic melt to the cross sectional area of the plastic in its final product form, be it a
tube, hose or insulation on a core, such as a wire or cable. It is the extent to which the
plastic has been reduced in size to make the part.
A larger DDR enables faster production rates, while a lower DDR facilitates more
precise control of the product dimensions. A low draw down ratio process is more
stable than a high one. Most products made by drawing a plastic melt are smaller in
cross sectional area than the tooling gap.
SHEET EXTRUSION OR FLAT FILM: In this the polymer melt is extruded through a
slot die (T-shaped or “coat hanger” die), which may be as wide as 3 meters for
making flat plastic sheets. The cooling is achieved by pulling through a set of cooling
rolls (calendar or "chill" rolls), usually 3 or 4 in number. These rolls not only deliver the
necessary cooling but also calibrate sheet thickness and surface texture (in case of
structured rolls; i.e. smooth, levant, haircell, etc.). Behind this the roller conveyor and
the draw-off rolls for air cooling are located. In coextrusion two or more extruders are
employed and the material extruded, forms the layers in required thickness. This
provides flexibility of combining the properties of different compatible material in to
one product or used for cost efficiency using regrind in middle layer.

The thinner gauges sheet are thermoformed into packaging applications such as
drink cups, containers, produce trays, baby wipe containers and margarine tubs
whereas Thick sheets used for industrial and recreational applications like truck bed
liners, pallets, automotive dunnage, window glazing, playground equipment and
tanks. Biaxially oriented film BOPP can be produced by a flat-film extrusion. The third
primary use for extruded sheet is in geomembranes, where flat sheet is welded into
large containment systems for mining applications and municipal waste disposal.
**A sheet is distinguished from a film by its thickness; by ASTM definition film as being
equal to or less than 0.25 mm in thickness and exceeding 0.25 mm it is a Sheet.
FOAM EXTRUSION: Process for producing plastic sheet of cellular construction.
Either a chemical or a gaseous blowing agent is introduced into the polymer melt
while the melt is being prepared in the extruder barrel. As the plastic melt exits the
die, it expands a predetermined amount, forming a cellular wall.

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